Tag Archives: Atypical osteoid osteoma

Answer: Photo Quiz #5

ANSWER: Atypical Osteoid Osteoma

ISSN 1941-6806
doi: 10.3827/faoj.2008.0106.0005

Osteoid Osteoma is a benign skeletal neoplasm of unknown origin. Focal bone pain is the hallmark of this tumor. [1] The tumor consists of ovoid or spherical nidus of osteoid-rich tissue and interconnected bone trabeculae superimposed against highly vascularized connective tissue containing large dilated vascular channels. The neoplasms are usually small, ranging from 0.5 cm to 2 cm in diameter. [1]

The common presentation of an osteoid osteoma is painful lesion in the diaphysis of the long bone, usually the femur or tibia, with a history of night pain, relieved by aspirin. Typically, on radiograph, it presents as a diaphyseal lesion or nidus less than 1 cm in size surrounded by extensive sclerosis. It has been reported that the lesion may become asymptomatic after a mean of 3 years following non-operative treatment. However, the majority of these lesions require surgical excision of the nidus, radioablation or ethanol injection as a sclerosing agent directly into the nidus or lesion.

Recently, percutaneous radiofrequency coagulation is the most common modality to treat osteoid osteoma without open surgery. This is usually performed by CT guidance under general or spinal anesthesia. After localization of the nidus with 1- to 3-mm CT sections, an osseous access is established with either a 2-mm coaxial drill system or an 11-gauge Jamshidi needle. RF ablation is performed at 90°C for 4-5 minutes by using a rigid RF electrode with a 1-mm diameter. [1] The procedure is successful when the electrode is heated to the desired temperature within the nidus. In one series, clinical success was achieved in 96% of patients. All recurrences were treated with a second procedure, with a secondary success rate of 100%. [2]

Atypical osteoid osteoma is one where clinical and radiological findings differ. This is usually seen with osteoid osteoma of the small bones or any juxta- or intra-articular osteoid osteomas. The non-specific features include synovitis, stiffness, joint contracture or scoliosis if the tumor is located in the spine. Radiographically, sclerosis is not apparent on plain films. Because of variable clinical presentation and paucity of radiological findings, the diagnosis is very often delayed. This delay has been reported to be anywhere between 6 to 24 months. It has been suggested that a high index of suspicion is necessary for early diagnosis and prompt treatment. Bone-scan, CT or MRI is helpful in diagnosis of the tumor.

The other choices in this photo quiz included osteochondritis dessicans (OCD lesion), osteoblastoma, Brodie’s abscess and Ewing’s tumor.

In the talus, osteochondritis dessicans is primarily a lesion isolated to the talar dome. It is classified as a type of osteochondral fracture.

Osteoblastoma is a rare primary neoplasm of bone most closely related to osteoid osteoma. [3] The clinical difference is its ability to grow larger than 2.0 cm in diameter. Osteoblastoma is a larger and more aggressive, benign neoplasm of bone.

Brodie’s abscess is a form of subacute or chronic osteomyelitis. [4] Although MRI findings may have been similar to osteoid osteoma, the histological difference in a Brodie’s abscess would have included bone degeneration, fibrosis, subacute inflammation with a mixture of polymorphs and plasma cells in an edematous background.

Ewing’s tumor is a class of malignant tumors of bone and soft tissue. In bone, Ewing’s sarcoma is a highly malignant primary bone tumor derived from red bone marrow. [5] Histologic features are closely related to reticulum cell sarcoma. The tumors are most commonly located in the metaphyseal or diaphyseal region of long bones.

In summary, early diagnosis and treatment of osteoid osteoma is recommended to avoid unnecessary suffering and late complications such as joint contracture.


1. Khan, Ali Nawaz. Osteoid Osteoma eMedicine [online], 2008.
2. Sung KS, Seo JG, Shim JS, Lee YS. Computed-tomography-guided percutaneous radiofrequency thermoablation for the treatment of osteoid osteoma-2 to 5 years follow-up. Int Orthop. Nov 22 2007,[Medline].
3. Ortmann, Fred. Osteoblastoma eMedicine [online], 2008.
4. Khalid, K. el al., Subacute Osteomyelitis (Brodie Abscess), eMedicine [online], 2008.
5. Strauss, L. Ewing Sarcoma, eMedicine [online], 2008.

Address correspondence to: Dr. Vasu Pai, Gisborne Hospital, Ormand Road, Gizborne, New Zealand.
E-mail: vasuchitra@gmail.com

Orthopaedic Specialist, Gisborne, Hospital, Ormand Road, Gisborne, New Zealand.

© The Foot & Ankle Journal, 2008

Photo Quiz: Bone Lesion to the Neck of the Talus

Vasu Pai MS, D[Orth], National board [Orth], FICMR, FRACS, MCh[Orth]1 , Vishal Pai, M.B., Chb2

The Foot & Ankle Journal 1 (6): 5

ISSN 1941-6806
doi: 10.3827/faoj.2008.0106.0005

Case History

An 8 year old boy presents with history of ankle pain for 4 months. His pain is mainly to the anterior aspect of the ankle joint. He had been limping for last 6 weeks. Clinical evaluation reveals tenderness over the dorsal aspect of the talus. The dorsiflexion of the ankle was terminally limited and extremely painful. The subtalar joint was normal. There is normal heel inversion on standing tip-toe.

Laboratory data was unremarkable. As symptoms did not settle at 6 months, the joint was aspirated under anesthesia. Two milliliter of straw colored fluid was aspirated from the ankle joint. Gram stain was negative and culture did not reveal any growth of organisms. Cell count was less than 2000 and suggestive of non-specific synovitis.

The plain radiograph of the ankle and foot is normal. The bone scan revealed an increased uptake in the left side of the talus. The CT scan revealed a small lesion which could be identified over the superior border of the talus with surrounding sclerosis. The MRI revealed increase signal intensity in T2 and decrease signal intensity in T1. (Fig. 1) There was increased enhancement with post gadolinium injection. A benign lesion was diagnosed.


Figure 1    T1 and T2 MRI shows signal intensity changes involving the neck of the talus.

The left ankle was surgically explored through an antero-lateral approach. The sensory branch of musculocutaneous nerve was preserved. The neck of the talus superiorly was irregular and was curetted very easily. (Fig. 2) The wound was closed in layers. The ankle was held in a neutral position in a short leg cast.

Figure 2    Irregular, soft, cystic-like material is easily curetted from the neck of the talus.

Histopathological examination showed abundant osteoid in fibrovascular stroma. The trabeculae were rimmed by prominent osteoblasts with no mitotic activity. (Fig. 3) At one year follow up there was no recurrence or the lesion. Patient is now totally asymptomatic.

Figure 3  Trabeculae rimmed by prominent osteoblasts in fibrovascular stroma.

Question: Based on the patient’s clinical history, MRI ,surgical and histologic findings, which of the following is the correct diagnosis?

A. Osteochondritis dessicans (OCD lesion)
B. Atypical Osteoid Osteoma
C. Osteoblastoma
D. Brodie’s Abscess
E. Ewing’s tumor


Address correspondence to: Dr. Vasu Pai, Gisborne Hospital, Ormand Road, Gizborne, New Zealand.
E-mail: vasuchitra@gmail.com

1 Orthopaedic Specialist, Gisborne, Hospital, Ormand Road, Gisborne, New Zealand.

2 House Surgeon, Middlemore Hospital, Auckland, New Zealand.

© The Foot & Ankle Journal, 2008