Malignant melanotic nerve sheath tumor

Abstract

Malignant melanotic nerve sheath tumor, previously known as melanotic schwannoma, is a rare variant of peripheral nerve sheath tumor composed of melanin-producing Schwann cells and clinically misdiagnosed as melanoma. Malignant melanotic nerve sheath tumor is a rare tumor with uncertain biological behavior and variable treatment recommendations. Despite the histological features that seem benign, with a low proliferation index, the clinical course of this tumor often becomes malignant, with a high frequency of local relapses and the presence of tumor metastasis signs. Distinctive features of malignant melanotic tumor of the nerve sheath are a relatively young age of patients, the presence of the Carney complex signs and psammomatous bodies in the tumor. The article presents a case of malignant melanotic tumor of the nerve sheath localized in the neck with a recurrent course. In the described clinical observation, the patient underwent surgical treatment twice. Microscopic and immunohistochemical analysis of postoperative materials gave a positive result for melanoma markers and showed the absence of psammoma bodies and low mitotic activity. The clinical course of the disease was malignant, with the appearance of a relapse in the postoperative scar. Diagnosis of malignant melanotic tumor of the nerve sheath is a complex task, both from the radiological and pathological points of view. Communication between the surgeon, radiologist and pathologist, understanding the anatomical relationships of the lesion and careful attention to the histological findings are critical to making the correct diagnosis.