Intracranial Melanotic Schwannoma: A Case Report of Recurrence with Extra- and Intradural Manifestation Two Decades After Initial Diagnosis and Treatment

Abstract

Melanotic schwannoma (MS) is a very rare nerve sheath tumor characterized by melanin-producing cells that display ultrastructural features of Schwann cells [24]. This type of tumor was first described in 1932 [17] and occurs primarily in the paraspinal region, originating from the spinal nerve roots or sympathetic ganglia. Craniofacial or intracranial locations are rare [15] [21]. However, extraneural locations such as skin, soft tissues, bone and viscera have also been described [5] [7]. In a minority of cases, MS may have multiple nodules [6] [26]. Although MS have been considered to be slow-growing, benign tumors, prognosis can be poor as a result of local recurrence or malignant progression [9]. Melanotic schwannoma occurs in relatively young adults (mean age 35 years) and have no sex predilection. Epidemically, two types of tumors can be distinguished: the sporadic variant and psammomatous melanotic schwannoma associated with the Carney complex, a rare, autosomal dominant hereditary syndrome characterized by variegated skin pigmentation, cardiac myxomas, endocrine overactivity, and nerve sheath tumors [2]. Psammoma bodies are present in more than 50% of MS. Immunohistochemistry reveals that S100, HMB-45 and vimentin are strongly expressed by most cells in MS [15] [18].