(18) Case of an adolescent girl with familial vulvar leiomyoma

Background: While uterine leiomyomas remain a common occurrence affecting nearly 30% of adult women above 35yo, leiomyomas can arise anywhere smooth muscle cells are located in the body. Vulvar leiomyomas are a particularly rare diagnosis, often misdiagnosed as Bartholin gland cyst, comprising 0.07% of vulvar tumors, and thought to arise from smooth muscle within the round ligament, erectile tissue, and dartos muscle. Even more rare is the presentation of vulvar leiomyoma in the adolescent population and family history of vulvar leiomyoma.

Case: We present the case of a 16yo girl who noticed a painless vulvar mass that had increased in size during the previous 7 months. Notably, the patient’s mother reported having a history of recurrent vulvar leiomyoma requiring multiple surgical excisions. Single digit vaginal exam revealed a solid well-circumscribed vulvar mass that involved the right labia majora and perineum, extending caudally to the level of ischial spine. MRI showed a 9.6 x 9.1 x 7.2cm vulvar mass suggestive of leiomyoma that displaced rectum to the left (Figure 1). A multidisciplinary surgical procedure with pediatric gynecology and colorectal surgery was performed. A longitudinal skin incision was made lateral to the right labia majora and extended inferiorly onto right of midline of the perineum (Figure 2). The mass was excised in its entirety from within the pararectal space, and dead space closed in layers with interrupted sutures followed by skin closure. Final specimen was 12.2cm in diameter, weighing 319g. Pathology report noted smooth muscle bundles composed of spindle cells with positive staining for smooth muscle actin and desmin, consistent with benign leiomyoma. Patient admitted overnight with vaginal packing, which was removed after 24 hours and the patient discharged to home on post-op day one.

Comments: There have been over 100 cases of vulvar leiomyomas reported with only 3 reported in adolescents. To our knowledge this is the first reported case have of familial vulvar leiomyoma. Though there are known syndromes of hereditary cutaneous leiomyomas, uterine fibroids, and renal cancer, no syndromes are known regarding inherited vulvar leiomyoma. In this case preoperative MRI was helpful for delineation of location of the mass, surgical planning and confirmation of clinical suspicion of leiomyoma given smooth muscle consistency on T2 weighted images. We opted for a paramedian skin incision rather than an incision at the mucocutaneous junction of the labia and vestibule often described in the literature to preserve the integrity of the vaginal canal.