Abstract
We encountered a case of granular cell tumor that occurred in sternocleidomastoid muscle. The case was a 61-year-old woman, whose chief complaint was a painless mass on the right collarbone. Above the right clavicular head, we palpated an immovable, moderately firm mass of about 2 cm in diameter. Cervical echo and cervical CT findings showed a mass in the right sternocleidomastoid muscle. We performed tumor resection, and the mass was diagnosed as granular cell tumor by postoperative pathological examination. By immunostaining, the tumor was positive for S100 and CD68. In view of a clear nucleolus and nuclear polymorphism, the tumor was pathologically of atypical type. Neither recurrence nor metastasis has been detected during two years and six months. Only one other case of granular cell tumor arising from the sternocleidomastoid muscle has been reported in Japan, suggesting the rarity of the tumor.
