Mixed malignant peripheral nerve sheath tumor in the inguinal region: a case report.

Malignant peripheral nerve sheath tumor (MPNST) is a rare malignant soft tissue tumor that accounts for approximately 5% of all soft tissue sarcomas. This tumor originates from the peripheral nerves and occurs mainly in the limbs, head and neck, and spine. As a more aggressive tumor, it has higher recurrence and metastasis rates, and patient prognosis is poor. MPNST has a variety of histologic subtypes such as classic MPNST and epithelioid malignant peripheral nerve sheath tumors (EMPNSTs). Due to the diversity of histologic types, these tumors have a high histologic similarity to other benign and malignant soft tissue tumors. Due to the lack of specific diagnostic criteria, pathologic diagnosis is extremely difficult, since these tumors should be differentiated from other sarcomas according to the site of tumor occurrence and morphologic characteristics, which can be determined using immunohistochemical staining. The specific pathogenesis of MPNST is not well understood. Studies have shown that approximately 50% of MPNSTs are closely related to neurofibromatosis I (NF1), while other causes of these tumors include radiotherapy. Herein, we report the first case of a mixed tumor composed of classic MPNST and EMPNST elements in the inguinal region.