Fetal Type Rhabdomyoma of the Soft Palate in an Adult Patient: Report of One Case and Review of the Literature

Abstract

Rhabdomyoma is a rare benign tumor with skeletal muscle differentiation. Rhabdomyoma is further classified into cardiac, adult, fetal, and genital subtypes. Out of these, fetal type rhabdomyoma (FTR) is the rarest. Only a small number of cases have been recorded in the literature. FTR typically affects male infants and young children and occurs predominantly in the head and neck region. FTR is exceedingly rare in the adult, with less than 30 cases reported. The classic FTR is composed of primitive undifferentiated spindle cells with scant eosinophilic cytoplasm embedded in a myxoid stroma. Immunohistochemically, the tumor cells are positive for desmin, muscle specific actin, and myogenin. Awareness and proper recognition of this rare entity is of considerable importance to avoid misdiagnosis of embryonal rhabdomyosarcoma. In this study, we report one case of FTR in an adult patient and reviewed the literature about the clinical and pathologic presentation of FTR in the adult.

Keywords: Benign spindle cell tumor; Rhabdomyoma; Rhabdomyosarcoma.

Fig. 1

Photograph of the polyp by flexible laryngoscopy (a). Three-dimensional computed tomography scan of the polyp (b–d) showing that the polyp is attached to the nasal side of soft palate

Fig. 2

Whole mount picture of the resected polyp (a). Mass with intact overlying mucosa (b, ×40). Primitive spindle cells with delicate bipolar and unipolar eosinophilic cytoplasm (c, ×400). Scant myoblasts are located at the periphery of the lesion (d, ×400)

Fig. 3

Tumor cells are diffusely positive for desmin (a, ×200). Myogenin stains the nuclei of spindle cells and myoblast. Inflammatory cells show nonspecific cytoplasmic stain (b, ×200)