Osteofibrous Dysplasia-like Adamantinoma of the Tibia in a 15-Year-Old Girl.

Osteofibrous dysplasia and adamantinoma are rare lesions of primary benign and malignant bone tumors with an incidence of less than 1%. These lesions arise primarily in long bones with a predilection for the tibia and fibula. Osteofibrous dysplasia is a benign fibro-osseous lesion typically found in children younger than 10 years. Adamantinomas, however, are highly malignant and invasive tumors found predominantly in adult men, with an average age of diagnosis between 20 and 50 years. Debate continues on whether osteofibrous dysplasia and adamantinoma occupy the same disease spectrum. Within the spectrum of pathology lies a rare benign lesion known as osteofibrous dysplasia-like adamantinoma. This intermediate form has the potential to spontaneously regress or transform into a malignant adamantinoma. We report a rare case of an osteofibrous dysplasia-like adamantinoma of the tibia in a 15-year-old girl. The patient was followed with regular 3- to 6-month follow-ups. The lesion remained stable and showed no progression over 2 years. Given the benign nature of osteofibrous dysplasia and osteofibrous dysplasia-like adamantinoma and the malignant nature of adamantinoma, correctly diagnosing the lesion has significant treatment implications. This case report highlights the rarity of this intermediate form and its potential to remain stable. Such lesions can be observed with frequent follow-ups without the need for surgical intervention.