Primary tumor size predicts pathologic findings in the retroperitoneal lymph nodes in patients with paratesticular rhabdomyosarcoma.

To determine patient and tumor characteristics that could predict pathologic findings after retroperitoneal lymph node dissection (RPLND) in paratesticular rhabdomyosarcoma (PTRMS), a total of 266 cases of PTRMS diagnosed between 1973 and 2010 were identified from a national database. RPLND dissection was performed in 67 patients, with a mean age of 14.9 years and median survival of 80 months. PTRMS occurred more often on the right side, had embryonal histology, and had an average size of 6.7 cm. Retroperitoneal lymph node (RPLN) metastasis occurred in 40 % (n = 27) of patients. Tumor size and age were strong predictors of finding rhabdomyosarcoma in the retroperitoneal lymph nodes when examined by pathologists. Primary tumors larger than 7 cm in size developing in males 12 years or older had four times more odds of being associated with positive findings on pathologic examinations of the retroperitoneal lymph nodes. Patient race, histology, and tumor laterality were not significant predictors of PTRMS metastasis to the RPLN basin. Patients 12 years or older with PTRMS larger than 7 cm have a significant risk of retroperitoneal lymph nodes involvement with PTRMS. Detailed pathologic examination of the lymph nodes in these patients is recommended.