Intramasseteric schwannoma treated with facelift incision and retrograde facial nerve dissection

Abstract

Schwannoma is a slow-growing, well-demarcated, benign soft tissue tumor of the peripheral nerve sheath. It commonly develops in the head and neck region, usually in the parapharyngeal space. In this case, a 42-year-old woman visited the outpatient department to manage a painless mass on her left cheek. She had no history of concern and no neurological symptoms were observed. In the enhanced computed tomography scan, a 2.8 × 2.8 × 1.8 cm, heterogeneously enhanced tumor was detected in the left masseter muscle. A tumor resection under general anesthesia was planned. For the resection, a facelift incision was chosen; branches of the facial nerve were identified and retrogradely dissected. A well-marginated, yellowish, solid mass was found in the left masseter muscle. The mass was excised and given a histopathological diagnosis of schwannoma. A definite diagnosis of schwannoma, originating in the masseter muscle, is difficult to arrive at with radiographic findings alone; it is often misdiagnosed as intramuscular hemangioma. Histopathological examinations, including fine-needle aspiration or histological biopsy after surgery, are necessary. Using a facelift incision with retrograde facial nerve dissection, tumor resection in an intramasseteric lesion can be performed efficiently, without nerve damage, or leaving conspicuous scars on the face.

Intramasseteric Schwannoma Mimicking a Parotid Tumor: Case Report and Review of Literature

“…A review of the English-language literature reveals only 10 reported cases of schwannomas located at the intramasseteric region (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). As shown in Table 1, a female-to-male ratio of 1:1 was observed and there is no signi cant gender predilection.…”

“…As evident in Table 1, FNA biopsies were performed in 4 cases and all inconclusive, indicating that FNA has a low accuracy in the diagnosis of schwannoma. Therefore, the conclusive diagnosis is only achieved based on microscopic ndings of the harvested tissues, characterizing with a speci c cellular Antoni A areas and less organized hypocellular Antoni B areas [16][17][18][19][20].…”

“…For intramasseteric schwannoma, it is di cult to identify the original nerve of the tumor since the tumor always obliterate a small nerve in masseter muscle. All reported cases were treated with tumor excision through different approach, including extraoral or intraoral approach, which was mainly depended on the location and involvement of tumor (15,17,19). An extraoral incision such as a preauricular incision or a submandibular incision is often unavoidable for the intramasseteric schwannoma.…”

“…Intraoral approach accompanied with endoscope is feasible for tumor removal when the tumor size is limited (15). Similar with the surgical approach for parotid tumor, facelift incision was also used to excise the intramasseteric schwannoma (19). Super cial or total parotidectomy is not required for management of intramasseteric schwannomas.…”

Schwannoma of the posterior branch of the great auricular nerve

“…In these cases, a schwannoma can be removed by including only part of the fascicles or by cutting the capsule. However, if there is significant fascicular involvement, neurorrhaphy or a nerve graft may inevitably be required to minimize neurologic deficit after en bloc excision [ 10 , 11 ]. Although schwannomas are benign, incomplete excision can cause a slow local recurrence over months to years [ 9 ].…”