Schwannoma or neurilemmoma is a rare benign nerve sheath tumor, usually presenting as a solitary, painless, slow growing, fleshy mass. It is located subepidermally, but produces skin swelling, depending on the size and exact location in the skin.1 It usually arises from schwann cells of peripheral, cranial and autonomic nerve sheaths, and rarely affects female external genitalia.2 All schwannomas are positive for S-100 protein, and almost all are benign with less than 1% risk of malignancy.3
Figure 1: Vulvar schwannoma. (a) Pedunculated mass originating from left labium majus. (b) Excised mass. (c) Cut section of the mass shows a lobulated growth with areas of hemorrhage and necrosis.
A 49-year, P7+0, with last childbirth 8 years back, presented with a large vulvar growth. The mass was about 12×10 cm, circumscribed, solid and subcutaneous in origin. It was showing high vascularity and occupying the lower part of left vulva through a long pedicle of approximately 5×3 cm in size (Figure 1a). The ultrasound with doppler studies revealed multiloculated and well defined hypoechoic swelling, which was fairly vascular. No free fluid was seen in the mass. Surgical excision of the mass was performed (Figure 1b). Cut section showed lobulated lesion with whorlled appearance of fibers, pale in colour with multiple haemorrhagic and necrotic areas, resembling leiomyoma (Figure 1c). Histologically, the tumor was composed of bundles of banal spindle shaped cells with palisading of nuclei. No mitoses were found. The tumor was surrounded by a fibrous capsule. The tumor showed hemorrhagic and necrotic areas. Immunohistochemically, tumor was positive for S-100 and negative for smooth muscle markers, CD34 and NF, which confirmed the diagnosis of schwannoma. One year post-excision follow-up showed no reoccurrence.
Schwannoma is a slow growing nerve sheath tumor, which is widely distributed in the body, but is rare in vulva. It can occur at any age as reported in elderly patients.4 The clinical presentation of vulvar schwannoma is very confusing on the basis of its macroscopic features as the possibility of laprosarcoma, fibrosarcoma, Bartholin’s gland cyst, and other mesenchymal tumors cannot be ruled out until histopathological and immunohistochemical analyses are done.5 Malignant schwannoma is associated with high frequency of mitotic figures and is extremely rare.
In conclusion, vulvar schwannoma is a very rare benign nerve sheath tumor. Surgical excision with clear margins is curative with negligible risk of reoccurrence. It should be considered in the differential diagnosis of any slow growing vulvar mass.
CONFLICT OF INTEREST:
The authors declared no conflict of interest.
FN: Conception or designs’ of the work, acquisition, analysis, or interpretation of data for the work, revising it critically for important intellectual content and final approval of the version to be published.
AQ: Design of the work.
NA: Drafting of the work.