Answer: Sinonasal glomangiopericytoma (sinonasal-type hemangiopericytoma)

Histology: none provided

Discussion: Glomangiopericytoma (GP) is now the prefered term to refer to sinonasal-type hemangiopericytoma. Recent evidence suggests a closer histogenic association with perivascular modified smooth-muscle cells, similar to that of a glomus tumor, but distinctly different from soft-tissue hemangiopericytoma. GP peak incidence is in the seventh decade. Most affected patients experience nasal obstruction and epistaxis. GP have a polypoid clinical appearance with an average size of 3 cm. Clinically they can be mistaken for inflammatory polyps.

Histologically, GP are richly vascularized tumors composed of bland spindle-to-ovoid cells with indistinct cytoplasmic borders and storiform or whorled architecture. Nuclear palisading can be seen. The tumor vasculature demonstrates the typical ramifying “staghorn” or “antler-like” configuration seen in hemangiopericytoma. Extravasated erythrocytes, mast cells, and eosinophils can be present.

Immunohistochemically, GP are postive for smooth muscle actin and vimentin and only focally positive for CD31. CD34 and Factor 8 are usually negative. (This case showed very focal, weak CD34 positivity). Positivity for Factor XIIIa can be encountered (this case was weakly positive). GP are clinically indolent tumors that are cured by complete resection. Additional surgery will usually address occasional recurrences.

Reference(s):
– Thompson LD, Miettinen M, Wenig BM. Sinonasal-type hemangiopericytoma: A clinicopathologic and immunophenotypic analysis of 104 cases showing perivascular myoid differentiation. Am J Surg Pathol 2003;27:737-49.
– Thompson LD. Sinonasal tract glomangiopericytoma (hemangiopericytoma). Ear Nose Throat J. 2004 Dec;83(12):807.