Smooth Muscle Tumors of the Female Genital Tract

[Practical diagnostic aspects of uterine leiomyosarcoma in the context of the 2020 WHO classification]

The 2020 WHO Classification defines the spindle cell, epithelioid, and myxoid variants as subtypes of uterine leiomyosarcomas (LMS). Presence of cellular atypia (size variation of polymorphic nuclei > 2-3:1), tumor cell necroses, and mitotic count (usually ≥ 10 MF/10 HPF) are still the key features for diagnostic separation from uterine leiomyomas. Preanalytic variables, staining quality, as well as intralesional geographic distribution may affect the mitotic count. Smooth muscle tumors of uncertain malignant potential (STUMP) still exist as a not yet well-characterized diagnostic entity. Immunohistochemical stains against p16, p53, Ki-67, and WT‑1 may aid differential diagnosis in selected cases. Diagnostic molecular pathology is not yet relevant for diagnosis.

Beyond Smooth Muscle-Other Mesenchymal Neoplasms of the Uterus

Mesenchymal tumors of the uterus comprise a heterogeneous group of neoplasms of varied biologic potential. In addition to being host to several anatomically unique entities, the uterus may contain mesenchymal neoplasms typically found elsewhere in the body. Although smooth muscle neoplasms are common, other mesenchymal neoplasms in this location are relatively rare. Many of these neoplasms exhibit morphologic overlap. In addition to a careful histomorphologic review, definitive classification frequently depends on the judicious application of ancillary immunohistochemical and molecular testing. The intent of this review is to offer a basic approach to the classification of primary uterine mesenchymal neoplasms.

Proposed novel nomenclature of vulvar smooth muscle tumors; a case of Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP) of the vulva

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Clinical experience with smooth muscle tumors of the vulva is limited.

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Some tumors present ambiguous histological features concerning for malignancy.

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These include infiltration, mitotic activity, size, atypia and tumor cell necrosis.

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A case of smooth muscle tumor of the vulva with cellular atypia is presented.

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“Smooth Muscle Tumor of Uncertain Malignant Potential” of the vulva is advocated.