"Sclerosing" Pelvic Floor Rhabdomyoma

Molecular assessment of paratesticular rhabdomyomas demonstrates recurrent findings, including a novel H3C2 p.K37I mutation

Rhabdomyomas are benign tumors with skeletal muscle differentiation that are broadly divided into cardiac and extracardiac types. The latter demonstrate a predilection for head and neck and genital locations and are further subclassified into adult-type rhabdomyoma (ATRM), fetal-type rhabdomyoma (FTRM) and genital rhabdomyoma (GRM). Most extracardiac rhabdomyomas that arise in paratesticular tissues have a somewhat distinctive morphology and have been termed sclerosing rhabdomyomas (SRM). Therefore, we hypothesized that these tumors may harbor recurrent genetic alterations. In this study, we assessed 15 paratesticular rhabdomyomas (11 initially classified as SRM, 2 cellular FTRM and 2 ATRM) using massively parallel DNA and RNA sequencing. Five of 14 successfully sequenced cases harbored a novel H3C2 p.K37I mutation (4 SRM and 1 ATRM). This mutation replaced a highly conserved lysine residue that is a target for epigenetic modifications and plays a role in regulation of DNA replication. Moreover, 4 tumors (2 cellular FTRM, 1 case initially diagnosed as SRM and 1 ATRM) had complex copy number profiles characterized by numerous chromosome-level and arm-level copy number gains, consistent with a ploidy shift. Rereview of the SRM with copy number gains demonstrated that it was significantly more cellular and had a more prominent fascicular architecture than the rest of the SRMs included in this series. Therefore, it was retrospectively reclassified as a cellular FTRM. In conclusion, this study demonstrated that paratesticular rhabdomyomas harbor recurrent somatic H3C2 p.K37I mutations and ploidy shifts.

Case Report and Review of the Literature of a Rare Entity of a Uterine Fibroid: A Genital Rhabdomyoma

Extracardiac rhabdomyomas are rare benign tumors. According to histopathologic and clinical characteristics, they are divided into 3 subgroups: adult, fetal, and genital rhabdomyomas. Various adult extracardiac rhabdomyomas have been reported in the head and neck region, whereas genital rhabdomyomas are uncommon. Here, we report on a uterine genital rhabdomyoma in a 32-yr-old woman with secondary sterility. After myomectomy, the histopathologic analysis showed a slow cycling tumor with striated muscle differentiation and without any evidence of malignancy. Immunohistochemical staining proved coexpression of actin, caldesmon, and desmin. To the best of our knowledge, this is the first case of a uterine-based genital rhabdomyoma.

Rare periurethral fetal rhabdomyoma presenting as a vaginal mass

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