Leiomyosarcoma: A Rare Tumor of the Vulva

Objective Primary sarcomas of the vulva are very rare malignancies, accounting for 1% to 3% of all gynecologic sarcomas. Leiomyosarcoma is the most common histologic type. They present with nonspecific symptoms, aggressive behavior, and high metastatic potential. Methods A 63-year-old female patient presented with a 6-month history of a slow-growing, painless vulvar mass at the right posterior fourchette. CT scan revealed an asymmetric, heterogeneous vulvar mass extending to the distal vagina, without lymphadenopathy or evidence of distant metastasis. Focal prominence of the uterus suggestive of leiomyoma was also noted, but primary uterine neoplasm with vulvar metastasis could not be excluded. The patient underwent wide local excision of the vulvar mass with hysterectomy and bilateral salpingo-oophorectomy. Results Gross examination of the vulvar specimen showed an ulcerated 2.1-cm solid white mass with irregular borders. Microscopically, the vulvar tumor consisted of a focally infiltrative spindle and pleomorphic neoplastic proliferation with interlacing fascicular pattern and increased mitotic activity up to 25/10 HPF, without necrosis or lymphovascular invasion. The tumor focally extended to resection margins. Immunohistochemically, the neoplastic cells were positive for SMA, ER, and desmin and negative for S-100 and cytokeratin AE1/AE3. These findings, in conjunction with the clinical presentation, were consistent with high-grade primary vulvar leiomyosarcoma. Radiation therapy was subsequently started. Conclusion Primary vulvar leiomyosarcomas are rare and secondary involvement by uterine primary should always be ruled out. In addition, these tumors can be mistaken clinically as benign processes such as Bartholin gland cysts, infectious granuloma, fibroma, or myoma. Hence, it is vital to consider vulvar sarcomas in the differential diagnosis of nonspecific vulvar lesions in order to avoid delay in diagnosis and treatment. The rarity of this diagnosis makes this case worth reporting.