Paratesticular Fetal-type Rhabdomyoma in a 12-Year-Old Boy: A Case Report and Literature Review

[Paratesticular rhabdomyosarcoma: about a case and literature review]

Nous rapportons une observation d´un rhabdomyosarcome embryonnaire paratesticulaire chez un adulte jeune et soulignons le caractère inhabituel de cette forme histologique dans cette tranche d´âge, l´évolution rapide de la lésion ainsi que les difficultés de prise en charge de ce type de tumeurs dans notre contexte.

Pediatric Benign Tumors With a Skeletal Muscle Component: Myogenin Expression, Diagnostic Pitfalls, and New Molecular Insights

OBJECTIVES

Benign tumors with skeletal muscle differentiation are rare and their characterization in the literature is limited. We present a series of twelve pediatric benign tumors with rhabdomyomatous differentiation including seven rhabdomyomatous mesenchymal hamartomas, four fetal rhabdomyomas, and one benign triton tumor, analyzing myogenic markers as well as clinicopathologic and molecular features. A review of the literature was also performed with an emphasis on myogenic marker expression and correlation with molecular features.

METHODS AND RESULTS

Cases obtained from three tertiary pediatric hospitals were retrospectively reviewed. Eleven of twelve cases expressed myogenin in rare to greater than 15% of cells. Five of nine cases had rare to 70-80% of cells positive for MyoD1. One fetal rhabdomyoma demonstrated homozygous deletions in ZEB2. The benign triton tumor harbored a CTNNB1 mutation. Review of the literature identified 160 pediatric benign tumors with skeletal muscle differentiation of which 9 reported myogenin positivity.

CONCLUSIONS

Myogenin and MyoD1 may be variably expressed in benign lesions with skeletal muscle differentiation. Recognition of key morphologic features remains critical to diagnose these lesions and, in rhabdomyoma, to exclude malignancy. Our series expands the knowledge of the relationship between rhabdomyoma and rhabdomyosarcoma (RMS) by identifying a shared molecular alteration in ZEB2.

"Sclerosing" Pelvic Floor Rhabdomyoma

PURPOSE

This article reports on a sclerosing perineal-perianal rhabdomyoma in an adult woman. A review of the literature disclosed no reference to this histological form of rhabdomyoma in women.

METHODS AND RESULTS

We describe the case of a 48-year-old woman. At physical examination, a firm nodular lesion was identified in the left lateral perianal-perineal region. Histologically, it comprised rounded and elongated muscle fibers displaying no evident atypia, within a stroma exhibiting marked sclerosis and mild lymphoid infiltrate. At immunohistochemical examination, tumor cells stained for desmin, muscle-specific actin, and myogenin.

CONCLUSIONS

Skeletal muscle rhabdomyomas are rare benign tumors, generally divided into 3 major categories depending on their clinical and morphological characteristics: fetal, adult, and genital. An unusual histological variant of the genital form has recently been reported in men, characterized by the presence of predominantly mature muscle fibers and marked sclerosis. We document such a lesion in a female patient for the first time.

[Embryonal paratesticular rhabdomyosarcoma: a case report and a literature review]

Paratesticular rhabdomyosarcoma is a rare tumor. Multimodality treatment should involve surgery, radiotherapy and chemotherapy, which are indicated according to risk groups. Risk group stratification depends on pretreatment staging and definitive histology. Patients older than 10years or those with suspected lymph nodes on imaging have higher incidence of lymph node involvement. Prognosis is excellent for localized tumors, survival rates exceed 90%. We report a case of embryonal paratesticular rhabdomyosarcoma treated in our institution.