Perineal nodule due to enterobiasis: an aspiration cytologic diagnosis.

Subcutaneous swelling due to Enterobious vermicularis infection is rare. Their presence in perineal subcutaneous tissue is unusual and a clinical curiosity. A case of subcutaneous nodule in the perineum due to E. vermicularis infection diagnosed on fine-needle aspiration is described. Tissue reaction was granulomatous with neutrophils and eosinophils. Lack of familiarity with the morphology of parasites or its eggs, degeneration, and inadequate sampling may make the diagnosis difficult. This case report provides the morphologic clues to cytopathologists toward rendering a diagnosis and alerts them to the possibility of parasitic infection in unusual locations.