Intramuscular lipoma within the temporal muscle

A 61-year-old male presented with a 6-month history of a subcutaneous nodule on the left forehead, which had gradually enlarged. He had suffered from headaches from 20 days before the first visit. His medical history included hepatitis C virus infection. He had had no history of trauma in this area. Clinical examination showed a subcutaneous soft nodule, 15 x 15 mm in size, which was adjacent to the left superficial temporal artery (Fig. 1). Though this artery revealed strong pulsation, the nodule had neither pulsation nor tenderness. His headache was localized in the left temporal area. He had no complaints of fever or weakness. Clinically, these features suggested a pseudoaneurysm of the superficial temporal artery. We operated on him under local anesthesia. An incision through the skin and subcutaneous fat exposed a nodule located within the temporal muscle. The fine branches of the superficial temporal artery reached out to the nodule through the muscle. After ligation of the branches, we resected the nodule surrounded by muscular tissue. Histopathology showed the proliferation of mature adipose cells embedded in muscular fibers. These cells had no nuclear pleomorphism or mitoses (Fig. 2). The tumor tissue contained partial fibrosis and some muscular fiber bundles scattered between the adipose cells (Fig. 3). Intramuscular lipoma within the temporal muscle was diagnosed. His headache was reduced after the operation, and he has had no recurrence of the tumor for 16 months. The relationship between the tumor and his headache was unknown.