A MEDICAL SERVICES PROVIDER
                     "people caring for people"

Case of the Month




May 2021

38 year-old female with a 3 cm left nasal cavity polyp. Histologic sections show subepithelial, well-demarcated but not capsulated, cellular mesenchymal proliferation composed of uniform, round to spindle cells concentrated around a vascular component that shows “antlar” formations. Scattered mast cells and eosinophils are easily seen; rare mitoses were identified. The tumor shows focal reactivity for SMA and CD34 (highlights background vessels), while desmin and S100 are negative. Diagnosis: Sinonasal Glomangiopericytoma.

Glomangiopericytoma (sinonal-type hemangiopericytoma) is a rare (<0.1% of sinonasal neoplasms), benign mesenchymal proliferation of pericytic (perivascular) myoid phenotype and characteristic hemangiopericytoma-like background vasculature. Pathogenesis involves mutational activation of B-catenin with resulting nuclear staining on immunohistochemistry. Vast majority will show positivity for SMA (or other smooth muscle actins) while they are negative for desmin, keratin, S100, CD117 (highlights scattered mast cells) and CD34 (highlights vascular architecture). The tumor has excellent prognosis after surgery, but in about a third of cases, it will recur or persist, warranting long-term follow-up.