Spindle Cell Rhabdomyosarcoma
Spindle cell rhabdomyosarcoma (RMS) is a well-recognized variant of embryonal RMS that is predominantly seen in the paratesticular region of adolescent males. It has a significantly lower rate of lymph node metastasis as compared to the non-spindle embryonal RMS. The overall prognosis is better with an improved 5-yr survival rate. A spindle cell variant of embryonal RMS has been described in adults as well; however, it involves head and neck region more commonly and appears to have a more aggressive clinical course. The tumor is composed of long fascicles of spindle cells with elongated, vesicular nuclei and pale indistinct cytoplasm. Scattered spindled or rounded rhabdomyoblasts with brightly eosinophilic cytoplasm may be scattered throughout the tumor. The differential diagnosis includes : fibrosarcoma, leiomyosarcoma, or malignant peripheral nerve sheath tumor. Leuschner I et al. Spindle Cell Variants of Embryonal Rhabdomyosarcoma in the Paratesticular Region : A Report of the Intergroup Rhabdomyosarcoma Study. Am J Surg Pathol 17(3):221-230, 1993.Nascimento AF & Fletcher CDM; Spindle Cell Rhabdomyosarcoma in Adults. Am J Surg Pathol 2005; 29:1106-1113.