We report a case of an intramuscular hemangioma of the masseter muscle that required differentiation from a parotid tumor and was managed surgically. A 50-year-old woman presented at our hospital with progressive swelling in her left cheek five years duration. Physical examination and MRI images revealed a mass within her left masseter muscle that was partially in contact with the anterior aspect of the parotid gland and appeared strongly high signal on the T2-weighted images. Dynamic imaging indicated a pattern of dense staining and gradual enhancement, prompting differential diagnosis between a parotid tumor and an intramuscular hemangioma. Surgical intervention was performed by a trans-parotid approach, and intraoperative exploration confirmed that the tumor was enclosed within the masseter muscle, and several branches of the facial nerve were observed to course over the muscle, superficial to the tumor. The tumor was easily dissected from the surrounding masseter muscle, and was resected. Histopathological examination confirmed the diagnosis of cavernous hemangioma, and no malignant features observed. The patient did not develop facial nerve paralysis, and her postoperative recovery was uneventful, with no functional or aesthetic complications. There has been no recurrence of the hemangioma. Careful surgical management is necessary for complete resection of intramuscular hemangiomas to avoid postoperative facial nerve paralysis.
Koga et al. (Thu,) studied this question.