Clinicopathological analysis of osteofibrous dysplasia and adamantinoma: A single institution experience

Osteofibrous dysplasia (OFD) and adamantinoma are rare primary bone tumors. The present study is a clinico-pathological analysis of OFDs and adamantinomas, highlighting the value of distinguishing these tumors from their mimics and evaluating their proximity. OFDs, adamantinomas, fibrous dysplasias (FDs), and intraosseous synovial sarcomas (SS) of the tibia and fibula, diagnosed from 2012 to 2024 (12 years) were retrieved. Fifty-eight tumors were reviewed, and finally, 19 OFDs and 28 adamantinomas were analyzed. After a review, the diagnosis was modified in 12/58 (20.7%) tumors; with 4 OFDs revised to FDs; 2 FDs to OFDs; 2 intra-osseous SSs to classic adamantinomas; 3 OFD-like adamantinomas to classic adamantinomas, and a single de-differentiated adamantinoma to classic adamantinoma. The median age for OFD (10 years) was lower than that of adamantinoma (25 years). The radiological impression concurred with the histopathological diagnosis in 40% of OFDs and 60% of adamantinomas. Among 28 adamantinomas, there was a single OFD-like adamantinoma, 25 classic adamantinomas, and 2 dedifferentiated adamantinomas. Pan keratin (AE1/AE3) was positive in 18/19 (94.7%) OFDs and 19/20 (95%) adamantinomas. P40 (5/5, 100%) and p63 (6/8, 75%) were useful in the diagnosis of adamantinoma. Most adamantinomas were treated with surgery. None of the OFDs progressed to an adamantinoma during a median follow-up of 51.15 months(range = 4.36 to 97.94 months). Five out of 28 (17.9%) patients with an adamantinoma developed recurrences and 5 (17.9) developed metastases. The most commonly associated patterns with recurrences and metastasis in a classic adamantinoma were spindle and basaloid. The present study constitutes the first and the largest series of OFDs and adamantinomas from our subcontinent. OFD, OFD-like adamantinoma and adamantinoma may display overlapping clinico-radio-pathological profiles, and as such are potentially associated with diagnostic errors. Although there is a morphological continuum between OFD and adamantinoma, we did not observe a disease progression during the limited follow-up. It is crucial to distinguish an OFD and an adamantinoma from their various mimics, given treatment-associated implications. A long-term follow-up is suggested, as recurrences and metastases can occur late during the disease course.