Abstract. Neurothekeoma is a rare myxoma of the peripheral nerve sheath. The current report presents a case of a giant neurothekeoma with a partially-formed capsule, scapula erosion and unclear biological behavior, which originated in the intermuscular space between the left trapezius muscle and scapula. The patient was initially misdiagnosed with a fibromatosis using computed tomography and magnetic resonance image scanning. Diagnosis of the neoplasm was confirmed by pathological and immunohistochemical examination, revealing a neurothekeoma with unclear biological behavior. The patient underwent a wide and complete local resection. Using a comprehensive postoperative follow-up strategy, it was determined that the patient recovered well. The tumor was ~17x16x10 cm in size and was in contact with the scapula. The purpose of the present study was to describe a rare giant neurothekeoma and review the diagnostic techniques utilized to reach a definitive diagnosis. Histopathological and immunohistochemical analyses were recommended for the diagnosis of neurothekeoma. There have been no previous reports regarding neurothekeomas exhibiting malignant transformation. Early and complete surgical resection is considered to be an effective method of treating this type of neurothekeoma.