Hematoxylin-eosin–stained sections showed an irregularly acanthotic epidermis with flattened rete ridges. The dermis was completely replaced by sheets of bland stellate or spindle-shaped cells embedded in a myxoid stroma with variably sized vascular channels lined by cytologically bland endothelial cells.
Spindle cells had pale eosinophilic cytoplasm with ill-defined cell borders and no clinically significant cytologic atypia. Occasional mitoses were observed. By immunohistochemical stains, lesional cells were strongly positive for vimentin and CD34, focally positive for factor XIIIa, and negative for pancytokeratin, S-100 protein, and desmin.
CARRIE ANN RC, SENAIT ANN WD, MOLLY AH, VINCENT L. Recurrent Erythematous Vulvar Nodule on a 33-Year-Old Woman—Diagnosis. Arch Dermatol. 2010;146(8):911-916. doi:10.1001/archdermatol.2010.172-b