A 67-year-old female complained about swelling of the left temporal area with a 4-month history. She had no previous history of trauma in the region. On examination, there was a firm, hemispherical mass 40
mm in diameter in the temporal area; overlying skin appeared normal. The mass was immobile against underlying bone. Trismus or facial palsy was not observed ().
Preoperative view of the patient.
Magnetic resonance imaging (MRI) revealed a relatively well-demarcated mass in the left temporal muscle, which showed low signal intensity on T1-weighted images and high signal intensity admixed with irregular low signal areas on T2-weighted images (). Computed tomography showed an ill-demarcated round mass. Heterogeneous enhancement of the mass and adjacent temporal muscle was observed between the coronoid process and temporal fossa (). A highly vascularized soft tissue tumor with malignant potential was suspected based on the aggressive features indicated by radiology and rapid growing of the lesion.
Preoperative MRI on T2-weighted image showing high signal intensity admixed with irregular low signal areas in left temporal fossa.
Preoperative contrast CT showing ill-demarcated low-density mass with enhancement of the adjacent temporal muscle.
An incisional biopsy was performed under general anesthesia to evaluate histology. The specimen revealed proliferation of dilated small vessels with hemorrhage associated with inflammatory components. Abnormal mitotic figures were not observed. Histological features suggested a benign or intermediate vascular tumor, particularly angiolymphoid hyperplasia with eosinophilia.
Surgical excision was performed under general anesthesia. First, a hemicoronal incision of the scalp was made; subsequently, the superficial surface of the temporal muscle and zygomatic arch were exposed. A solid nodule was palpated in the temporal muscle and continued beneath the zygomatic arch (). Osteotomy of the zygomatic arch was performed, and the bone fragment was temporarily removed. The entire temporal muscle was bluntly dissected from adjacent bones, revealing no bony involvement. Then, the temporal muscle was severed just distal to the coronoid process and at the distal insertion, removing the tumor with the muscle en bloc. Finally, the zygomatic arch fragment was replaced and fixed with 3/0 absorbable sutures. A suction drain was inserted in the temporal fossa, and the scalp wound was closed in two layers. The surgical specimen showed thin-walled cavernous vessels lined by endothelial cells, hemorrhage, and spindle-shaped cells with inflammatory cell infiltration. Abnormal mitotic figures or cellular atypia was not observed (Figures and ). These histological characteristics led to a diagnosis of SCH. Postoperative course was uneventful. No signs of local recurrence were observed during two years of followup. Postoperative complications such as facial palsy, trismus, or alopecia have not been observed. The patient was satisfied with the aesthetic result, though a mild depression was observed in the temporal area ().
Intraoperative view demonstrating intramuscular tumor (arrows) with the assistance of zygomatic osteotomy (asterisks).
Figure 5 Microscopic findings of the spindle cell hemangioendothelioma. (a) Low-power view of the lesion showing cavernous blood vessels filled partly or completely with erythrocytes or thrombus admixed with cellular zones (hematoxylin-eosin, original magnification (more ...)
Postoperative view at 24 months followup.