Retiform hemangioendothelioma: a rare lesion of the vulva

Retiform hemangioendothelioma (RH) is a rare borderline-malignant vascular tumor with specific histological characteristics, usually occurring in the limbs and trunk. We report the case of a 63-year-old woman who presented with a painless, oval nodule that had been growing slowly on her left vulva for 3 years. Magnetic resonance imaging of the pelvic cavity revealed a 4.4- x 2.7- x 1.8-cm cystic lesion in the subcutaneous fat of the left vulva. Resection beyond the macroscopic border was performed. Pathology revealed vascular structures with elongated and narrow arborizing vascular channels that were arranged in a retiform pattern resembling rete testis tissue. Immunohistochemical endothelial staining was positive for CD31, CD34, and Friend leukemia integration-1 (FLI-1). The above features confirmed a diagnosis of RH. There was no local recurrence or metastasis during the 26-month follow-up. RH of the vulva is rare, and its diagnosis is supported by specific histological characteristics and immunohistochemical staining for CD31, CD34, and FLI-1. Wide surgical resection with tumor-free margins is important for a favorable prognosis.