Angiomatoid fibrous histiocytoma: a review with recent genetic findings.

Angiomatoid fibrous histiocytoma is a neoplasm of intermediate biologic potential most often arising in the extremities of children and young adults. Its rarity may lead to misdiagnosis as either a reactive lesion or a benign or higher-grade tumor. Originally described as a type of malignant fibrous histiocytoma, its differentiation remains enigmatic, with precise histogenesis still only hypothesized. Its morphology is distinct, as a circumscribed lesion with sheets of bland spindle to ovoid cells, peripheral lymphoplasmacytic infiltrate, and blood-filled cystic cavities, and half of the cases show strong desmin expression. Cytogenetically, 2 specific translocations, t(12:16)(q13:p11) and more recently t(12:22)(q13:q12), have been characterized. The literature on angiomatoid fibrous histiocytoma is reviewed, particularly with regard to recent molecular genetic developments and differentiation, and its morphology, immunohistochemistry, and differential diagnosis are summarized.