Superficial myofibroblastoma of the lower female genital tract: A clinicopathological analysis of 15 cases

Objective: To describe the clinicopathological features and differential diagnoses of 15 cases of superficial myofibroblastoma, a rare mesenchymal tumor involving the lower female genital tract.

Methods: The clinicopathological data and immunohistochemical findings were retrospectively analyzed in 15 cases of superficial myofibroblastoma. Meanwhile, a systematic literature review was conducted.

Results: The age of patients ranged from 34 to 73 years (median, 49 years). Most patients presented with nodular or polypoid masses ranging in size from 0.4 cm to 6.5 cm. Twelve tumors were located in the vagina, two in the vulva, and one in the cervix. Microscopically, the tumor was located in the subepithelial tissue, with a clear boundary and without capsule on the surface. The tumor cells were spindle, oval, stellate or wavy, and arranged in various architectural patterns of reticular, fascicular, wavy and disorderly patterns. There were no obvious cellular atypia and mitotic figures. Thin collagen fibers and thin-walled vessels could be observed in all cases. Most cases were diffusely and strongly reactive to Vimentin (12/12), Desmin (14/15), ER (15/15) and PR (13/14). Variable immunoreactivity for CD34 (8/15), Caldesmon (2/8), SMA (4/14) and CD99 (4/5) were observed. The tumors showed a low Ki67 proliferative index (≤5 %). Follow-up information was available in 10 patients and there was no evidence of recurrence or metastasis.

Conclusions: Superficial myofibroblastoma is a rare benign tumor that originates from the hormone-sensitive, subepithelial mesenchymal tissue of the lower female genital tract, and should be differentiated from other mesenchymal tumors.