Melanotic Schwannomas Are Rarely Seen Pigmented Tumors with Unpredictable Prognosis and Challenging Diagnosis

Abstract

Melanotic Schwannoma (MS) is rarely seen and potentially malignant neoplasm that is categorized as a variant of Schwannoma. MS most frequently involves intracranial structures followed by posterior nerve roots in the spinal canal. Approximately 50% of the cases with MS have psammomatous calcifications and this type of MS is related to Carney complex with autosomal dominant inheritance. Most cases of MS are benign, though 10% of them are malignant with metastatic potential. MS mimics melanoma and the differential diagnosis should be made excluding other melanin producing neoplasms especially melanoma. Case 1. A 42-year-old hypertensive male presented for checkup. He had a well-defined extraspinal oval lesion measuring 3.5 × 2.5 cm near right adrenal. Case 2. A 22-year-old female presented with neurofibromatosis-2, bilateral acoustic schwannomas and café au lait lesions on sacrococcygeal region. She had an intradural extramedullary lesion measuring 6.1 × 2.0 cm at L1-2 level. MS is a rare neoplasm composed of Schwann cells and melanin pigment. These tumors are usually benign but they may become aggressive. The biologic behavior of MS is difficult to predict; the patients have to be followed up for a longer period due to its malignant potential.

Intradural Extramedullary Spinal Neoplasms: Radiologic-Pathologic Correlation

“…At MRI, spinal melanotic schwannoma is usually located along a spinal nerve root, sometimes with dumbbell morphology (42,43). Even more rarely, the tumor may arise within the spinal cord (44,45).…”

Vagal schwannomas of the head and neck: A comprehensive review and a novel approach to preserving vocal cord innervation and function

“…They are positive for HMB‐45, melan‐A, and tyrosinase, melanocytic markers . They tend not to have differentiated Antoni A and B areas, and also often lack Verocay bodies . Melanotic schwannomas can be further broken down into psammomatous and nonpsammomatous melanotic schwannoma .…”

“…They tend not to have differentiated Antoni A and B areas, and also often lack Verocay bodies . Melanotic schwannomas can be further broken down into psammomatous and nonpsammomatous melanotic schwannoma . Nonpsammomatous is sporadic, whereas psammomatous is associated with Carney Complex, an autosomal dominant genetic syndrome that presents with myxomas in various organs including the heart, breast, and uterus, as well as endocrine tumors …”

Melanotic Schwannoma of the Vagina: A Report of a Very Rare Tumor and Review of the Literature

“…Melanotic schwannoma (MS) is a rare nerve sheath tumor composed of Schwann cells, some of which are pigmented [1, 2]. MS is thus considered a variant of schwannoma, though the clinical and histopathological features of the two lesions differ greatly.…”

“…To date, fewer than 200 cases of MS have been reported worldwide and they account for less than 1% of all nerve sheath tumors [1]. MS has a predilection for intracranial structures and spinal nerve roots [1, 2]. There is no sex predilection.…”