Extraorbital giant cell angiofibroma.

We describe a case of giant cell angiofibroma (GCA) in extraorbital location. A 47-year-old man developed a subcutaneous tumor on the forearm, which measured 6 cm in diameter and was well demarcated. Histologically, small-sized vessels similar to arterioles, sometimes with a hyalinized wall, were regularly distributed throughout the tumor tissue. Lesional cells were oval and spindle in shape with pale eosinophilic cytoplasm and plump nuclei with clumped chromatin. In addition, larger bizarre cells with lobulated hyperchromatic nucleus were randomly admixed. Areas with a sieve-like pattern contained small slit-like spaces or larger pseudocystic spaces lined by tumor cells with an admixture of bizarre cells. Both mononuclear and bizarre lesional cells expressed strongly and diffusely vimentin and CD34. Negative reactions were with cytokeratins, bcl-2, desmin, actin, VWF, S100, alpha-1-antitrypsin, CD99, lysozyme and FXIIIa. Our finding confirms that GCA is a benign neoplasm not necessarily confined to orbital location. The patient did well without recurrence after 13 months of follow-up.