High incidence of regional and in-transit lymph node metastasis in patients with alveolar rhabdomyosarcoma

Rhabdomyosarcoma has different extension patterns, including a higher propensity for lymph nodes metastasis, compared with other types of soft tissue sarcoma. The aims of this study were to investigate the patterns of regional and distant metastasis in patients with rhabdomyosarcomas, particularly lymphatic route metastasis, and clarify the clinical factors that affect the pattern of metastasis.

Forty-four patients with rhabdomyosarcomas were enrolled in this study. The mean age of the patients was 26 (range 1–69) years, and 18 were males. The histological subtypes included alveolar (17 patients), embryonal (10 patients), pleomorphic (7 patients), and unknown (10 patients). Based on location, the sarcomas were divided into three groups: extremity (17 cases), favorable prognosis (10 cases), and unfavorable prognosis (15 cases). There were three cases (7 %) of local relapse, ten cases of regional lymph node relapse, and three cases of in-transit metastasis (total 30 %). Twenty-one patients (48 %) developed distant metastases. Initial sites of metastases were bone (9 patients, 20 %), lung (5 patients), and bone marrow dissemination (5 patients). Clinico-pathological variables affecting relapse patterns were analyzed.

Of the three cases of local relapse, two were alveolar type and one was unknown. The three cases of in-transit metastasis were all alveolar type. Patients with alveolar type had a significantly high propensity for lymph node metastasis (P = 0.027). Excluding the pleomorphic type, alveolar type was still a significant factor for lymph node metastasis (P = 0.017).

Physicians should be aware of in-transit spread, particularly in patients with alveolar-type rhabdomyosarcoma. Novel treatment modalities are required to detect and treat in-transit metastasis.