Sentinel lymph node mapping and biopsy: a potentially valuable tool in the management of childhood extremity rhabdomyosarcoma

Multimodal therapy, involving surgery, chemotherapy and radiation, now dominates the management of rhabdomyosarcoma (RMS) in childhood. Yet, despite improvements in these practices, extremity tumors continue to fare relatively poorly. Several investigators have identified prognostic factors that can be used to direct therapy and predict outcome. These factors include histology and metastatic disease, the latter requiring accurate staging to identify. The presence of lymph node metastases has been shown to be of prognostic significance and is incorporated into pre-treatment staging schemes. Up to 50% of all surgically evaluated nodes and 17% of clinically negative nodes in extremity RMS may harbor tumor, underscoring the increased risk of understaging the disease if accurate lymph node dissection is not undertaken. Despite its importance, there appears to be no standard format by which regional nodal status is evaluated in extremity RMS. Sentinel lymph node mapping and biopsy are a minimally invasive technique, currently used in the staging of adult breast cancer and melanoma. In adults, the technique is associated with optimum nodal yield and low morbidity. We describe a case in which sentinel node mapping and dissection were used to easily and accurately stage a distal upper extremity alveolar RMS in a child with clinically and radiologically negative regional lymph nodes. The procedure yielded no positive nodes, was associated with no morbidity and spared the child more extensive radiotherapy. We propose the further evaluation of this simple and innovative technique in the overall management of this childhood malignancy.