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Soft Tissue Aneurysmal Bone Cyst: A Case Report

Posted on June 1, 2011 | Comments Off on Soft Tissue Aneurysmal Bone Cyst: A Case Report

by Kevin M McCann, DPM 1  , Craig E Clifford, DPM 2 , Heather L Salton, DPM, AACFAS 3 

The Foot and Ankle Online Journal 4 (6): 1

The authors present an unusual case of a primary soft tissue tumor having histologic features identical to an intraosseous aneurismal bone cyst. A retrospective chart and radiographic review of a 44 year-old male was performed with a 17 month follow-up. Initially presenting as a painful, palpable nodule on the medial left ankle; a discreet, encapsulated mass was confirmed with ultrasound and magnetic resonance imaging. Surgical excision followed and pathologic analysis of the specimen diagnosed an aneurysmal bone cyst in soft tissue. Aneurysmal bone cysts usually appear in the metaphyses of long bones or in vertebral bodies. The primary soft tissue tumor is rare, with only 17 cases having been reported in the English literature. This is the first report of a primary soft tissue aneurysmal bone cyst in the distal lower extremity. In this case, as in the majority of reported cases, complete resolution was obtained with surgical excision.

Key words: Aneurysmal Bone Cyst, Tumor, Magnetic Resonance Imaging, Case Report

Accepted: April, 2011
Published: June, 2011

ISSN 1941-6806
doi: 10.3827/faoj.2011.0406.0001

Aneurysmal bone cyst (ABC) is classically described as a benign lesion developing mostly in the metaphyses of long bones and in vertebral bodies. [1] They are characterized by blood-filled spaces separated by connective tissue septa containing fibroblasts, osteoclast-like giant cells, and reactive woven bone. [2] ABC is considered a non-neoplastic lesion, although some cytogenetic studies have found reproducible chromosomal abnormalities. [3,18] The majority of ABCs arise de novo (primary ABC), but some have been found associated with other bony lesions secondarily. [4,15]

Lesions usually appear on radiograph as lytic and expansile. Computed tomography (CT) or magnetic resonance imaging (MRI) modalities often show a heterogeneous lesion with fluid-filled cystic spaces surrounded by a thin rim of bone. [5] Standard treatment of ABCs with marginal, yet complete surgical excision has shown acceptable results. [3,5,6]

While traditionally classified as a more common benign tumor of bone, ABCs have rarely been described as being found in soft tissues. A search of the English literature found a total of 17 cases of soft tissue ABC, with no primary lesions previously described in the distal lower extremity. [3,4, 7-16]

Case Report

The patient is a 44 year-old male who originally presented with complaints of a palpable “knot” in his medial left ankle, separate from and incidental to his chief complaint of hallux limitus on the contralateral limb. Initial exam showed a firm, semi-mobile, deep mass approximately 2cm proximal and immediately posterior to the medial malleolus. This was mildly tender to palpation, but did not restrict motion of the lower extremity. Ultrasound exam revealed a 5 x 10mm mass posterior to the tibialis posterior tendon. The mass was heterogeneous and ill-defined, without evidence of attachment to adjacent structures.

After one month of observation, the patient expressed continued pain and possible increasing size. An MRI exam was performed to show a 1.8 x 1cm heterogeneous mass abutting the flexor digitorum longus tendon. (Figs. 1A, 1B and 1C) A decision was made to perform a complete excisional biopsy.

  

Figure 1A, 1B and 1C  Magnetic resonance images (MRI) showing the heterogeneous, well-encapsulated mass immediately posterior to the flexor digitorum longus tendon.  (A) Coronal Proton-dense T2.  (B)  Sagittal T1 image.   (C)  Axial T1 Image.

Surgical dissection revealed a firm, purplish-brown, well-encapsulated mass within membranous soft tissue and with no defined attachment to surrounding structures. (Fig. 2A)

The mass was tagged with suture to identify orientation and submitted to pathology as a single specimen. (Fig. 2B) The patient healed uneventfully with full weight-bearing in the immediate post-operative phase.

 

Figure 2A and 2B  Intra-operative (A) and gross specimen photos (B) showing the excised mass with attached membranous soft tissue, and its location posterior to the tibialis posterior tendon.

The specimen margins were inked per orientation and the mass was sectioned to reveal a “variegated red-yellow cut surface with calcified tissue and extensive hemorrhage.” Microscopic analysis proved inconclusive and slides were sent to an outside pathology lab for independent review by multiple pathologists. The final pathology report is as follows: “The specimen is a circumscribed nodular heterogeneous lesion.”

Hemosiderotic synovium and a pool of muscular-walled, variably sized vessels are seen at the periphery of the nodule. The nodule had a vaguely multilobulated configuration with blood-filled pseudocystic spaces alternating with spindle cell areas and areas of bone formation. The center of the lesion is occupied by well-formed bone with spicules that radiate outward. The outer rim of the nodule demonstrates a discontinuous thin shell of bone. Numerous giant cells are seen within the blood filled spaces. Prominent hemosiderin deposition is seen within the intervening spindle-cell areas. The histologic features are those of so-called aneurismal bone cyst of soft tissue. (Fig. 3) No neoplasm is seen. The patient remains without symptoms or signs of recurrence at a follow-up of 17 months post-operatively.

Figure 3   Prepared H&E stained slide showing histologic features of aneurysmal bone cyst in soft tissue at 40X magnification.

Discussion

Unlike the more common primary bone lesion, soft tissue aneurysmal bone cyst is a rarely occurring pathology. A search of English language databases revealed a total of 17 cases of soft tissue ABC as reported by 12 authors. [3,4,7-16]

Salm and Sissons [7] first described two cases of extraosseus giant-cell tumors having histologic features identical to bony ABC in 1972. Since then, 16 cases (including this report) have been reported occurring in various locations, and are summarized in Table 1. Patients are made up of eleven females and six males ranging in age from 7 – 60 years with a median age of 28. Tumors showed histologic features identical to the bony ABC and ranged in size from 1.8cm to 10cm with a median of 4cm. Lesions were most often located in the deep soft tissues of the upper extremity or shoulder [7], or thigh. [3] All cases described were treated by surgical excision. Recurrence rate is unknown due to the small number of cases and inadequate follow-up.

Table 1  Summary of reported cases of soft tissue aneurysmal bone cyst (ABC).

Recently, Karkuzhali et al., [15] described a case of multiple soft tissue ABC’s arising following excision of a bony ABC from the proximal fibula 20 months prior, possibly suggesting a neoplastic course. Cytogenetic studies [3,18] have shown an association with translocations at the 16q22 and 17p13 loci, providing further evidence of a possible neoplastic etiology. It has been proposed that the lesion is first formed as a reaction to ectopic bone, but is more likely the result of a primary arteriovenous malformation. [3]

Despite the usual appearance of aneurysmal bone cyst in long bone metaphyses, the foot and ankle surgeon should be aware that it may also manifest as a soft tissue lesion of the lower extremity.

The differential diagnosis of soft tissue ABC can include nodular fasciitis and ossifying fibromyxoid tumor. Nodular fasciitis lesions may histologically mimic soft tissue ABC, but do not contain the characteristic pseudocystic spaces or thin shell of bone. Ossifying fibromyxoid tumors often show spicules of bone, but are without osteoclastic-like giant cells characteristic of soft tissue ABC. [3] Definitive diagnosis is made based on microscopic pathology, which is undistinguishable from the classic bony lesion. (Fig. 4)

Figure 4  Pathologic identification of soft tissue ABC.

The exact etiology of soft tissue ABC’s remains unknown. While the lesion can be aggressive in growth, it is benign and can be successfully treated with surgical excision.

References

1. Vergel De Dios AM, Bond JR, Shives TC, McLeod RA, Unni KK. Aneurysmal bone cyst. A clinicopathologic study of 238 cases. Cancer 1992 69: 2921-2931.
2. Leithner A, Machacek F, Haas OA, Lang S, Ritschl P, Radl R, Windhager R. Aneurysmal bone cyst: a hereditary disease? J Pediatr Orthop B 2004 13: 214-217.
3. Nielsen GP, Fletcher CD, Smith MA, Rybak L, Rosenberg AE. Soft tissue aneurysmal bone cyst: a clinicopathologic study of five cases. Am J Surg Pathol 2002 26: 64-69.
4. Fellig Y, Oliveira AM, Margolin E, Gomori JM, Erickson-Johnson MR, Chou MM, Umansky F, Soffer D. Extraosseous aneurysmal bone cyst of cerebello-pontine angle with USP6 rearrangement. Acta Neuropathol 2009 118: 579-581.
5. Abuhassan FO, Shannak AO. Subperiosteal resection of aneurysmal bone cysts of the distal fibula. JBJS 2009 91B:1227-1231.
6. Chowdhry M, Chandrasekar CR, Mohammed R, Grimer RJ. Curettage of aneurysmal bone cysts of the feet. Foot Ankle Int 2010 31: 131-135.
7. Salm R, Sissons HA. Giant-cell tumors of soft tissues. J Pathology 1972 107: 27-39.
8. Amir G, Mogle P, Sucher E. Case report 729: myositis ossificans and aneurysmal bone cyst. Skeletal Radiology 1992 21: 257-259.
9. Petrik PK, FindlayJM, Sherlock RA. Aneurysmal cyst, bone type, primary in an artery. Am J Surg Pathol 1993 17: 1062-1066.
10. Rodriguez-Perralto JL, Lopez-Barea F, Sanchez-Herrera S, Atienza M. Primary aneurysmal cyst of soft tissues (extraosseus aneurysmal cyst). Am J Surg Pathol 1994 18:632-636.
11. Lopez-Barea F, Rodriguez-Perralto JL, Burgos-Lizaldez E, Alvarez-Linera J, Sánchez-Herrera S. Primary aneurysmal cyst of soft tissue: report of a case with ultrastructural and MRI studies. Virchows Arch 1996 428: 125-129.
12. Shannon P, Bedard Y, Bell R, Kandel R. Aneurysmal cyst of soft tissue: report of a case with serial MRI and biopsy. Human Pathol 1997 28: 255-257.
13. Ajilogha KA, Kaur H, Duncan R, McFarlane JH, Watt AJ. Extraosseous aneurismal bone cyst in a 12 year-old girl. Pediatr Radiol 2005(12):1240-2.
14. D’Costa GF, Hastak MS, Patil YV. Primary aneurysmal cyst: bone type in the breast. Ind J Surg 2007 69: 248-250.
15. Karkuzhali P, Bhattacharyya M, Sumitha P. Multiple soft tissue aneurysmal cysts: An occurrence after resection of primary aneurysmal bone cyst of fibula. Ind J Orthop 2007 41:246-249.
16. Sahu A, Gujral SS, Gaur S. Extraosseous aneurysmal cyst in hand: a case report. Cases J 2008 1: 268.
17. Harrop JS, Schmidt MH, Boriani S, Shaffrey CI. Aggressive “benign” primary spine neoplasms: osteoblastoma, aneurysmal bone cyst, and giant cell tumor. Spine 2009 34 (22 Suppl): S39-47.
18. Dai cin P, Kozakewich HP, Goumnerova L, Mankin HJ, Rosenberg AE, Fletcher JA. Variant translocations involving 16q22 and 17p13 in solid variant and extra osseous forms of aneurysmal bone cyst. Gen Chrom Cancer 2000 (28): 233-234.

Address correspondence to: Kevin McCann, DPM. Franciscan Foot and Ankle Institute, 34509 9th Ave S. Ste 306 Federal Way WA 98003
kevinmccann@fhshealth.org

1,2  PGY 2. Franciscan Foot and Ankle Institute, 34509 9th Ave S. Ste 306 Federal Way WA 98003.
3 Attending Staff, Franciscan Foot and Ankle Institute, 34509 9th Ave S. Ste 306 Federal Way WA 98003.

© The Foot and Ankle Online Journal, 2011

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A Rare Case of Aneurysmal Bone Cyst of the Calcaneum

Posted on April 1, 2011 | Comments Off on A Rare Case of Aneurysmal Bone Cyst of the Calcaneum

by Prasad Soraganvi1 , Karan Kukreja2 , Ramakanth R.3 

The Foot and Ankle Online Journal 4 (4): 1

Aneurysmal bone cyst (ABC) is a benign solitary lesion of unknown aetiology. ABC’s mainly occur in the long bones but only rarely in the bones of the feet. For example, frequency of occurrence in the foot is only 3% compared to other bones of the body. Very few cases of ABC involving the calcaneum have been reported. We report an unusual case of ABC of calcaneum in a 55 year-old male. Clinical presentation, histological diagnosis and treatment by curettage and bone grafting are described. The patient is now asymptomatic and there is no evidence of recurrence at 2 years follow-up.

Key words: ABC, calcaneum, curettage, bone grafting.

Accepted: March, 2011
Published: April, 2011

ISSN 1941-6806
doi: 10.3827/faoj.2011.0404.0001

The aneurysmal bone cyst (ABC) is an expansile cystic lesion that most often affects individuals during their second decade of life and may occur in any bone in the body. [1-5] Although benign, the ABC can be locally aggressive and can cause extensive weakening of the bony structure and impinge on the surrounding tissues.

Jaffe and Lichtenstein first described ABC in 1942. [6] As defined by the World Health Organization, the ABC is a benign tumor like lesion described as “an expanding osteolytic lesion consisting of blood-filled spaces of variable size separated by connective tissue septa containing trabeculae or osteoid tissue and osteoclast giant cells.” [4]

ABCs both erode and cause ‘expansion’ of underlying cancellous and cortical bone. [7] Around the lesion there is always a shell formed by periosteal new bone and, although this may be only millimeters thick, it prevents direct extension into the soft tissues. [8] The expansile nature of the lesions can cause pain, swelling, deformity, disruption of growth plates, neurologic symptoms (depending on its location), and pathologic fracture. [1-3]

ABC’s in the foot are uncommon. ABC’s present about 1% of all primary bone tumors collectively. [9] Its frequency of occurrence in foot is only about 3% compared to other bones of body. [10] Occurrence within the calcaneum are rare, and generally present as chronic heel pain and swelling, but may rarely present as pathologic fracture. [11]

A plethora of cystic lesions can occur in the calcaneum, which makes definitive diagnosis difficult based on imaging only. The differential diagnosis includes simple bone cyst, ABC (primary or secondary), chondroblastoma, giant cell tumor (GCT), osteosarcoma, ossifying hematoma or pseudotumor of hemophilia. This mandates histopathological diagnosis prior to the definitive management.

We report a rare case of ABC involving calcaneum of 55 year-old male confirmed by histopathology report and we performed curettage and bone grafting of cyst.

Case Report

A 55 year-old male, manual laborer by occupation and known diabetic on treatment presented with a chief complaint of swelling in right heel during the last two years. An increase in swelling was associated with pain in heel from the last one year. He had difficulty in walking because of pain. For the last two months, he was unable to work due to pain. He did give history of blunt trauma prior to the onset of symptoms.

Clinical evaluation revealed swelling over the lateral aspect of the heel and the skin over the swelling was stretched. Tenderness was present on palpation but there was no local rise of temperature. The swelling was bony hard in consistency and arising from calcaneum. There were no distal neurovascular deficits or any significant lymphadenopathy.

Radiographic examination of his ankle revealed an eccentric, expansile, multiloculated lytic lesion of the calcaneum with thin trabeculae traversing the cystic cavity. (Fig. 1) There was no breach in the cortex. Based on clinical and radiological findings, a diagnosis of benign cystic lesion of right calcaneum was made.

Figure 1 Pre-operative radiographs, antero posterior and lateral views showing eccentric expansile lytic lesion with thin shell of cortex and trabaculae traversing the cyst.

Open biopsy of the cyst was made to confirm the diagnosis. The cyst grossly consisted of cavities filled with brown altered blood. Histopathological report revealed large blood filled cavities lined by fibrous septa, with occasional osteoclastic giant cells. (Fig. 2A and 2B)

Figures 2A and 2B Histologic slides reveal large blood filled cavities lined by fibrous septa (A), with occasional osteoclastic giant cells, haemosiderin laden macrophages with a thin rim of bone. (B)

Hence the diagnosis of ABC involving the right calcaneum was made. The patient was scheduled for cyst curettage and bone grafting. By curvilinear incision over the lateral aspect of heel, the calcaneum was exposed. A large cortical window was made and the entire cyst curettage was done. Then the cavity was washed with saline and packed with cortico-cancellous bone graft harvested from both iliac crests in addition to synthetic bone substitute. The patient was advised non-weight bearing walking on the affected limb for eight weeks. Later mobilised with partial weight bearing walking for a further four weeks and then followed by full weight bearing on affected limb.

At six months of follow up, the patient was pain free and had returned to his regular activities. At two years follow-up, the patient is clinically asymptomatic. There is no evidence of recurrence. (Figs. 3A, 3B and 3C)

Figure 3: Follow-up radiographs showing incorporation of graft material at 1 month (A), 6 months (B), and at 2 years follow-up(C) showing consolidation of graft and no recurrence.

Discussion

ABC is an entity on its own having unique clinical, radiological and diagnostic behavior. [7] The true etiology of ABCs is unknown. Most investigators believe that ABCs are the result of a vascular malformation within the bone; however, the ultimate cause of the malformation is a topic of controversy. [12]

The concept of an ABC as a secondary phenomenon occurring in a pre-existing lesion is based on the fact that in approximately one-third of the cases a pre-existing lesion can be identified, the most common of which is giant-cell tumor. [13] ABCs are common around the knee joint of the young [11] and have an equal incidence in both genders. About 50-70% of ABCs occur in the second decade of life, with 70-86% occurring in patients younger than 20 years, which makes this case even more unusual. [10]

On histology, the ABC is characterized by blood filled cavities lined by fibrous septa. The stroma contains proliferative fibroblasts, spindle cells, areas of osteoid formation, and an uneven distribution of multinucleated giant cells. The tissue within the septations includes cavernous channels that do not contain a muscular or elastic layer in their walls. Areas of new and reactive bone formation can also be found in the ABC. Mitotic figures are common to ABCs, but no atypical figures should be evident. [10]

Bone cysts of the calcaneum are rare lesions. These may include a wide spectrum of non-neoplastic cysts, benign or malignant neoplastic lesions ranging from simple bone cyst, ABC (primary or secondary), chondroblastoma, giant cell tumor (GCT), and an osteosarcoma (especially telangiectatic). [11]

Clinically, calcaneal cysts are often symptomatic and present with heel pain, although some of these lesions may remain asymptomatic and are detected as incidental findings. Even though there are many typical radiograph, computed tomographic (CT) scan, and magnetic resonance imaging (MRI) findings to confirm a diagnosis of ABC, an open biopsy must be performed because of the high frequency of accompanying tumors. [11] When a biopsy is performed, the sample should ideally include material from the entire lesion; a limited biopsy could easily cause a coexisting lesion to be missed, leaving the patient with a morbid prognosis.

There are various methods of treatment based on the site and size of the lesion, which include curettage, which may be supplemented with various adjuvant therapies such as bone grafting, use of liquid nitrogen, phenol instillation and Poly (methyl methacrylate) (PMMA) cement.

Other modalities such as wide excision or arterial embolisation may be considered. Although relatively rare, there is no reason to assume that ABCs of the feet will respond to treatment or recur any differently from ABCs that occur elsewhere in the body. Surgical curettage is sufficient to treat most ABCs of the feet, including the calcaneum. [14]

Despite a favorable outcome of ABCs with an overall cure rate of 90-95%, [15] one of the most common problems encountered during management is frequent recurrence. The incidence of recurrence has been noted to vary between 59% in cases treated with intralesional excision [16] and 0% in cases with resection. Recurrence usually happens within the first year after surgery, and almost all episodes occur within 2 years. [17] Therefore, a patient of ABC needs to be observed for at least this period of time to exclude any recurrence. It is beneficial to detect recurrence early when the lesion is still small and easier to treat.

To conclude, ABC of the calcaneum is an extremely uncommon entity. Proper diagnosis entails correlating the clinical presentation, anatomical location, radiological profile, and histopathological appearance. This is imperative not only to exclude other more common histological mimics, but also for choosing the appropriate therapeutic regimen and prognosticating the disease outcome.

In a case of calcaneal cystic lesion, ABC should be considered as one of the differential diagnosis. Hence histological diagnosis is essential. Curettage and bone grafting is a valuable option.

References

1. Clayer M. Injectable form of calcium sulphate as treatment of aneurysmal bone cysts. ANZ J Surg 2008 78(5): 366-370.
2. Segall L, Cohen-Kerem R, Ngan B Y, Forte V. Aneurysmal bone cysts of the head and neck in pediatric patients: A case series. Int J Pediatr Otorhinolaryngol 21 2008: epub ahead of print.
3. Burch S, Hu S, Berven S. Aneurysmal bone cysts of the spine. Neurosurg Clin N Am 2008 19(1): 41-47.
4. Brastianos P, Gokaslan Z, McCarthy E F. Aneurysmal bone cysts of the sacrum: a report of ten cases and review of the literature. Iowa Orthop J 2009 29: 74-78.
5. Sun Z J, Zhao Y F, Yang R L, Zwahlen R A. Aneurysmal Bone Cysts of the Jaws: Analysis of 17 Cases. J Oral Maxillofac Surg Jan 26 2010 (Medline).
6. Jaffe H L, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture, the pathologic appearance and the pathogenesis. Arch Surg 1942 44: 1004-1025.
7. Campanacci M, Capanna R, Picci P. Unicameral and aneurysmal bone cysts. Clin Orthop 1986 204: 25-36.
8. Enneking WF. Aneurysmal bone cyst. In: Musculoskeletal tumor surgery. New York: Churchill Livingstone, 1983; 1513-29.
9. Duke Orthopaedics: Wheeless’ Textbook of Orthopaedics, Aneurysmal Bone Cyst, Online article, Jan 2007.
10. Anand MK, Wang EA. Aneurysmal Bone Cyst. eMedicine, Jan 2007.
11. Unni KK, Inwards YC. Conditions that normally simulate primary neoplasms of the bone. In: Unni K K, Inwards Y C, editors. Dahlin’s Bone Tumors. 6th edition. Philadelphia: Lippincott Williams and Wilkins; 2010. p. 305-80.
12. Cottalorda J, Bourelle S. Modern concepts of primary aneurysmal bone cyst. Arch Orthop Trauma Surg 2007 127(2): 105-114
13. Kransdorf MJ, Sweet DE. Aneurysmal bone cyst: concept, controversy, clinical presentation, and imaging. AJR 1995 164: 573-580.
14. Chowdhry M, Chandrasekar CR, Mohammed R, Grimer RJ. Curettage of aneurysmal bone cysts of the feet. Foot Ankle Int. 2010 31(2): 131-135.
15. Marcove RC, Sheth DS, Takemoto S, Healey JH. The treatment of aneurysmal bone cyst. Clin Orthop Relat Res 1995 311: 157-163.
16. Schreuder HW, Veth RP, Pruszczynski M, Lemmens JA, Koops HS, Molenaar WM. Aneurysmal bone cysts treated by curettage, cryotherapy and bone grafting. JBJS 1997 79B (1): 20-25.
17. Rastogi S, Varshney M K, Trikha V, Khan SA, Choudhury, Safaya BR. Treatment of aneurysmal bone cysts with percutaneous sclerotherapy using polidocanol. A review of 72 cases with long-term follow-up. JBJS 2006; 88B (9): 1212-1216.

Address correspondence to: Dr. Prasad Soraganvi, Dept of Orthopaedics and Traumatology, Meenakshi Mission Hospital and Research Centre, Lake Area, Melur Road, Madurai- 625107, India.

1 Consultant, Dept of Orthopaedics and Traumatology, MMHRC, Madurai.
2 Consultant, Dept of Orthopaedics and Traumatology, MMHRC, Madurai.
3 Senior Resident, Dept of Orthopaedics, DMH, Madurai.

© The Foot and Ankle Online Journal, 2011

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Aneurysmal Bone Cyst of the Middle Cuneiform: A case report

Posted on June 1, 2008 | Comments Off on Aneurysmal Bone Cyst of the Middle Cuneiform: A case report

by Al Kline, DPM1

The Foot & Ankle Journal 1 (6): 2

The incidence of Aneurysmal bone cyst (ABC) is rare. About 1% of all primary bone tumors constitute these lesions. They are most common in the upper extremity and rarely are reported in the foot. A case is presented reporting ABC of the middle cuneiform. To date, this appears to be the only documented case of ABC to the middle cuneiform. Surgical presentation and treatment using AlloMatrix ® bone putty as a moldable composite for an small, uncontained defect is described.

Key words: Aneurysmal Bone Cyst, ABC, Allomatrix® bone putty

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.  It permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ©The Foot & Ankle Journal (www.faoj.org)

Accepted: May 2008
Published: June 2008

ISSN 1941-6806
doi: 10.3827/faoj.2008.0106.0002

Aneurysmal bone cysts (ABC’s) in the foot are rare. This bone tumor is usually found in the upper extremity, along metaphyseal regions of bone. Its frequency of occurrence in the foot bones is about 3% compared to other bones of the body. [1] ABC’s represent about 1% of all primary bone tumors collectively. [2] The etiology is unknown, although it is now commonly accepted that benign bone cysts are caused by trauma. These tumors are benign and are characterized by expansile compartmentalization within cancellous bone. The lesions consist of blood filled spaces filled with connective tissue septa containing bone or osteoid and osteoclastic giant cells. [2] Differential diagnosis will include giant cell bone tumor, telangiectatic osteosarcoma and angiosarcoma.

The cyst is increasingly painful as it begins to expand, and diagnosis will usually be confirmed by ‘fluid-fluid’ levels and compartmentalization seen on CT and MRI.

The cyst always begins within the cancellous bone and can erode through the cortex and expand to surrounding articular bone. However, this is a slow process and usually increased pain is associated with the cyst before it has a chance to erode through the cortex. The cyst is slow growing.

Classification

Classification of aneurysmal bone cysts are often staged. Campanicci, et al., described five distinct stages of Aneurysmal bone cyst formation. [3]

Staging is based primarily on extent, size of cyst and its proximity to the cortex and soft tissue. Type 1 ABC usually occupies the center of the bone with intact or slightly expanded profile. In long bones, it is usually situated along the metaphyseal region of bone. In Type 2 ABC, the cyst will occupy the entire width of the bone with an enlarged profile. These larger central cysts are primarily metaphyseal. In Type 3 ABC, the cyst is eccentric and interosseous with minimal expansion to the cortex. In Type 4 ABC, the cyst is now under the periosteum with superficial erosion of the cortex. In Type 5 ABC, the cyst has expanded through the cortex and invades the surrounding soft tissue. (Table 1)

 

Type 1:  The cyst occupies the center of the bone with the profile either intact or slightly expanded.  The lesion is usually metaphyseal in nature.

 

Type 2:  The cyst occupies the entire width of bone and the profile is severely enlarged.  They are termed “central cysts” and are primarily metaphyseal.

 

Type 3:  The cyst appears as an eccentric, intraosseous lesion showing minimal expansion of the cortex.

 

Type 4:  The cyst is subperiosteal with superficial erosion of the underlying cortex.

 

Type 5:  The cyst has expanded into soft tissues and the cortex is destroyed. 

Table 1  Campanicci staging of aneurysmal bone cysts. 

Case Report

A 42 year old diabetic female presents to our office with a chief complaint of increased pain to the mid-tarsal region over the past year. There is no history of trauma. No allergies are reported. The patient is presently on medications for diabetes, hypertension and hypercholesterolemia.

The patient’s medical history is also significant for anemia, end-stage renal disease and heart disease. Surgical history includes cataract replacement and hysterectomy.

Clinical evaluation reveals good pulses. On neurological examination, the patient has advanced diabetic neuropathy; however, there is still point tenderness over the mid-tarsal joint along the middle cuneiform just proximal to the second metatarsal. This coincides with palpatory pain to the middle cuneiform. Radiographic evaluation reveals expansile changes to the second cuneiform noted on lateral radiograph. (Fig. 1)

Figure 1  Expansile changes to the bone are noted along the middle cuneiform.  Cystic changes appear to involve both the base of the 2nd metatarsal and middle cuneiform.

MRI was ordered, revealing fluid-fluid levels on axial T1 imaging. (Fig. 2-4)

  

Figures 2,3,4  T1 coronal/axial images reveal classic fluid-fluid within the superior pole of the middle cuneiform (Fig. 1). Significant cyst growth is noted along the main body of the middle cuneiform (Figs. 3,4).

Fat saturated post gadolinium T1 coronal axial study reveals high intensity changes within the superior half of the body of the cuneiform. (Figs. 5,6)

 

Figures 5,6  Fat saturated post gadolinium T1 images reveal fracturing and compartmental changes to the body of the middle cunieform.  In larger bones, this would correspond to the ‘soap-bubble’ effect often associated with the ABC.

Irregular cortical changes are consistent with fracturing of bone, and compartmentalization is seen in both T1 and T2 imaging. Closer examination of the inversion recovery sequencing or STIR images show cortical erosion extending along the proximal base of the second metatarsal base. (Figs. 7,8)

 

Figures 7,8  T1 images reveal extension of the cyst through the cortex of the middle cuneiform and base of the second metatarsal.  This would characterize the lesion as a Campanicci Type 5 ABC.

This would classify the cyst as Campanicci Type 5, with expansion of the cyst through the cortex and into soft tissue. A decision to schedule surgery was made and the patient was scheduled for cyst curettage with bone matrix therapy using AlloMatrix ® bone putty. [4]

Surgical Technique

A curvilinear incision was made directly over the middle cuneiform. Once deepened to the bone structure of the cuneiform, a curette was used to identify and dorsally window the cyst. The entire cyst was evacuated to firm bone structure at every margin. A portion of the second metatarsal base was also curettaged. The cyst appeared to invade just the superiomedial aspect of the base of the second metatarsal. (Figs. 9,10)

 

Figures 9,10  The dorsal cortex of the middle cuneiform and 2nd metatarsal base is curettaged.  A bone window is created revealing a soft cavity extending into the body of the middle cuneiform.

Material evacuated from the body of the cuneiform was sent to pathology. Pathology report revealed sections of decalcified specimen with fragments of bone and cartilage. Fragments of devitalized bone, marginated by cartilage and chondrocyte cloning with variable cellularity.

The material was serosanguineous in consistency. Areas of gelatinous-like material, deep red and purpuric in color were also evacuated from the body of the cuneiform.

The area and cavity were then lavaged with saline. AlloMatrix ® bone putty (Fig. 11) was mixed and impacted into the void. (Figs. 12,13)

Figure 11  AlloMatrix ® bone putty kit.

 

Figures 12,13  AlloMatrix ® bone putty is mixed and inserted into the defect.  The consistency of the putty can be varied by the amount of saline used to mix the substrate.

The surgical site was then closed in a layered fashion. Postoperative radiographs show the defect filled with synthetic bone graft. (Figs. 14,15)

 

Figures 14,15  Post operative radiographs reveal  AlloMatrix ® bone putty filling the cyst defect.

Discussion

In 1942, Jaffe and Lichtenstein first described ABC as a distinct entity when they discovered
“a peculiar blood-containing cyst of large size.” [5] Most ABC’s will occur between the ages of 10-30. [1] Seventy-five percent of reported ABC’s occur under the age of 20, which would make this case even more unusual. There are variable techniques used to treat ABC’s.

Some of these techniques include arterial embolization, intralesional injection, radionuclide ablation, local resection, en-bloc excision and intralesional removal.

Adjuvant therapies have also been attempted post resection including the use of liquid nitrogen and phenol. [6] Once the cyst is evacuated, a number of various materials have also been used to fill the void. The cavity can be packed with either bone autograft, heterograft and even polymethyl methacrylate. After treatment, the incidence of reported recurrence has ranged from 10 percent and higher. This has prompted additional studies on adjuvant treatments such as cryotherapy. [7]

In a landmark study by Gibbs, et al., forty patients treated with ABC excision by the same surgeon from 1976 to 1993 were reviewed. Thirty-four of the forty patients reviewed had curettage of bone using a high-speed burr. Of the twenty-two patients who had cancellous bone autogenous grafting, only 12% (4) had local recurrence. Of six patients who had resection of the cyst through its margin, none had recurrence. [7] In 1997, Schreuder, et al., from the University Hospitals of Nijmegen and Groningen, in The Netherlands, reported their results on curettage with the adjunctive use of cyotherapy. Twenty-Six patients with twenty-seven ABC’s were evaluated for complications and functional outcome after surgery. A mean follow-up of 47 months (19 to 154) was reported with only one local recurrence. They found similar results to those of marginal resection. When used in combination with bone grafting, they achieved bone consolidation in all of the patients. [8]

However, most of the past studies involve patients with large cysts of mostly long bones. Again, smaller bones such as cuneiforms, to this date, have not been reported. It was the author’s
choice to not use an adjuvant procedure after removal of the cyst.

In summary, this is a unique case of ABC in a diabetic female in her fourth decade. She does not fit the profile for development of this lesion, especially in the foot. However, due to her diabetes and associated neuropathy, it could be surmised that neuropathy and trauma may play an important role in the development of benign bone cysts.

References

1. Anand, M.K., Wang, E.A. Aneurysmal Bone Cyst. eMedicine, Jan, 2007
2. Duke Orthopaedics: Wheeless’ Textbook of Orthopaedics, Aneurysmal Bone Cyst, Online article, Jan 2007
3. Campanacci, M. et al: Unicameral and aneurismal bone cysts: A study of 416 UBC and 198 ABC. Clin Orthop 204:25, 1986
4. Wright Medical: AlloMatrix® Bone Putty with DBM&Cancellous Chips.
5. Jaffe, H.L., Lichtenstein, L.: Solitary unicameral bone cyst with emphasis on reoentgen picture, the pathologic appearance and the pathogensis. Arch Surg 44: 1004-1025, 1942
6. Eastwood, B., Biggs, H.K.: Aneurysmal Bone Cyst, eMedicine Online article, 2007
7. Gibbs, C.P. et al: Aneurysmal Bone Cyst of the Extremities. Factors Related to Local Recurrence After Curettage with a High-Speed Burr. JBJS 81:1671-1688, 1999. [Free online]
8. Schreuder, H.W., et al: Aneurysmal Bone Cysts Treated by Curettage, Cryotherapy and Bone Grafting, JBJS (UK), 79-B, No. 1, January, 1997.

 
Address correspondence to: Dr. Al Kline, DPM, 3130 South Alameda, Corpus Christi, Texas 78404. E-mail: al@kline.net

1Adjunct Clinical Faculty, Barry University School of Podiatric Medicine. Private practice, Chief of Podiatry, Doctors Regional Medical Center. Corpus Christi, Texas, 78411.

© The Foot & Ankle Journal, 2008

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