Presentation
Complaint of bulging in the left leg.
Patient Data
An osteolytic, well-defined expansile lesion with a sclerotic rim, located eccentrically in the posteromedial proximal diaphysis of the tibia, measuring 4.4 x 1.9 cm.
No cortical disruption, periosteal reaction, or soft tissue swelling.
Given the degree of insufflation and cortical thinning, it was decided to perform a CT and a biopsy.
The CT scan shows an expanded osteolytic cortical lesion with internal soft tissue density and well-defined sclerotic margins located in the proximal diaphysis of the tibia measuring 4.2 x 1.8 x 2.0 cm. There is pronounced thinning of the posterior cortical bone, without clear signs of fracture. No periosteal reaction or soft tissue mass.
Subcutaneous edema, soft tissue emphysema and a small cortical rupture indicate the site of the percutaneous biopsy.
The biopsy showed fusocellular proliferation without atypia, in a storiform pattern, permeating immature bone trabeculae (HE, 100x) and immature bone trabeculae bordered by active osteoblasts (HE, 400x).
Case Discussion
What makes this case interesting are the borderline (degree of expansion and cortical thinning) characteristics of the lesion which led to a biopsy for clarification.
The analysis of the images along with the biopsy results revealed an osteofibrous dysplasia. A bone scan was performed and showed that was a monostotic condition. Conservative treatment was adopted.
The imaging differential diagnosis would include adamantinoma which may be a related condition.
Contributors: Thanks to Dr. Hélio A. R. Júnior, head of the MSK Radiology department at HC-UFTM. And a special thanks to Dr. Felipe C. Batista, and Dr. Adilha M. R. Micheletti, pathologists who kindly provided the images from the pathology studies.
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