Ossifying fibromyxoid tumor of soft parts: a report of 17 cases with emphasis on unusual histological features.

Ossifying fibromyxoid tumor of soft parts is an unusual benign neoplasm, with a tendency for local recurrence. Its typical microscopic appearance is that of a multinodular proliferation of round to spindle shaped cells separated by fibrous bands in which bone formation is often seen. Herein, we present the clinicopathologic features of 17 examples of this tumor with particular emphasis on some unusual histopathologic features that may place pitfalls in the diagnosis of this tumor, including satellite micronodules, mucinous microcysts, absence of myxoid areas, crush artifact, multiple microcalcifications, epidermoid cysts, atypical chondroid differentiation with binucleate lacunar cells, pericytic growth pattern, and malignant change. Awareness of these unusual morphologic features should lead to a search for areas displaying the more typical features of ossifying fibromyxoid tumor to arrive at a correct diagnosis.