Differentiated adamantinoma of the fibula: a rhabdoid variant

A benign- appearing osteolytic lesion surrounded by a sclerotic rim was found in the upper fibula of a 25-year-old man. Based on histological features the definitive diagnosis of osteofibrous dysplasia-differentiated adamantinoma was made. The correct histological diagnosis of differentiated adamantinoma depends on factors such as the uniform predominance of an osteofibrous dysplasia-like pattern, and scattered epithelial elements positive for cytokeratin and vimentin. In this case the scattered epithelial cells had abundant eosinophilic cytoplasm and resembled rhabdoid elements, but immunohistochemistry proved their epithelial origin.