Radiation-induced high grade spindle cell sarcoma of the sternomastoid muscle : case report

Sarcomas developing as primary malignancies of the head and neck are a rare complication after radiation therapy. This kind of sarcoma has variable clinicopathological appearances and behaviour. Radiation-induced spindle cell rhabdomyosarcoma (RMS) of the sternomastoid muscle is a very rare sarcoma and has very seldom been described in the literature. Herein we report the development of a rapidly growing mass over the lateral side of the neck appearing after 7 years in a patient with a history of laryngeal carcinoma who received radiotherapy. The process of diagnosis and management using combined surgery and targeted brachytherapy are discussed. The patient experienced discomfort and oozing of the wound up to 2 months after surgery; however, complete response with satisfactory adaptation and shrinkage of the pectoralis major pedicled muscle flap occurred after 1 year. The patient is currently disease free 5 years postoperatively. Radiation-induced spindle cell rhabdomyosarcoma of the sternomastoid muscle after treatment for laryngeal carcinoma may occur a long time after radiation therapy and be clinically aggressive, radiographically distinctive, and require multidisciplinary management.