Mesenchymal Tumors of the Vulva: A Single-Center Experience with Overlapping Histologic and Immunophenotypic Features. Erem AS, Turashvili G.

Summary: Context: Vulvar mesenchymal tumors pose a unique diagnostic challenge. Overlapping histologic and immunophenotypic features require consideration of gynecologic and soft tissue neoplasms. Design: We evaluated 50 mesenchymal neoplasms of the vulva diagnosed in 2010-2022, including 34 expert consultations. Results: The median patient age was 48 years (range 19-74). There were 18 cellular angiofibromas (CAF), 19 angiomyofibroblastomas (AMFB), 5 leiomyomas (LM), 4 deep angiomyxomas (DAM), 2 solitary fibrous tumors (SFT), 1 leiomyosarcoma (LMS), and 1 gastrointestinal stromal tumor (GIST). Of 18 CAFs, 6 showed sarcomatous transformation, whereas 4 had cytologic atypia, increased mitoses, and necrosis; Rb1 was lost in 2 out of 3 cases. Lipomatous differentiation was seen in 3/19 AMFBs. Although immunohistochemistry was performed in 35 cases, the ultimate diagnoses relied on morphologic features. The GIST was originally diagnosed as LMS and reclassified following additional sampling. Of 16 cases with available clinical outcome, 9 (56%) recurred, with a recurrence rate of 100% (2/2) in SFTs, 100% (1/1) in LMS, 100% (1/1) in GIST, 50% (2/4) in LMs, 50% (2/4) in DAMs, and 33% (1/3) in CAFs. The cases with known outcome for CAF with atypia (1/4) and CAF with sarcomatous transformation (2/6) showed no recurrence. Conclusions: In our series of 50 vulvar mesenchymal neoplasms, CAF and AMFB were the most common. Accurate diagnosis of these tumors requires a combination of morphologic and immunophenotypic features. Although recurrences may occur and surgical resection can be challenging, most patients have a favorable prognosis, including those with cytologic atypia or sarcomatous transformation.