Primary myoepithelial carcinoma of the vulva and review of the literature.

Myoepithelial carcinoma of the vulva is extremely rare, with only five cases reported. Here, we describe a case of vulvar myoepithelial carcinoma along with a review of the literature. The patient, a 49-year-old woman, was referred for a tumor on the right labium majora. She underwent a wide local excision and bilateral inguinal lymph node dissection. Pathological examination revealed an unencapsulated, infiltrative pattern, with solid, nested and trabecular components and areas with myxoid or hyalinized stroma. The tumor consisted of oval to round epithelioid cells with moderate nuclear pleomorphism. By immunohistochemistry, the tumor cells were diffusely positive for cellular adhesion molecule (CAM) 5.2, epithelial membrane antigen (EMA), S-100 protein, and vimentin and focally positive for carcinoembryonic antigen (CEA) and p63, while negative for alpha- smooth muscle actin (SMA). The tumor was diagnosed as a myoepithelial carcinoma of the vulva, with metastases to the bilateral inguinal lymph nodes. Following completion of adjuvant radiotherapy, the patient remained alive without any evidence of recurrence at 56 months. A review of six cases of this tumor (including the present case), demonstrated variable morphology with some overlapping features. Therefore, immunohistochemistry using a panel of epithelial and myogenic markers is essential for definitive diagnosis. Two cases had inguinal lymph node metastases and received adjuvant radiotherapy or concurrent chemoradiotherapy, which resulted in good local control. One case had lung metastasis and was successfully treated by chemotherapy. Given the rarity of this disease and its uncertain prognosis, no clinical trials have been conducted regarding the necessity of adjuvant therapy. Myoepithelial carcinomas of the vulva are extremely rare making case series the most viable means of optimizing diagnosis and therapy.