Amelanotic Melanoma: Clinical Presentation, Diagnosis, and Management.

Abstract

Amelanotic melanoma (AM) is a subtype of cutaneous melanoma with little or no pigment on visual or histopathologic examination and makes up approximately 2% of melanoma cases. This uncommon variant is often misdiagnosed or diagnosed in late stages due to its variable clinical presentation and lack of established criteria for clinical diagnosis. AM often presents nonspecifically as pink to red macule, papule, or dermal nodule, therefore, dermatoscopy and reflectance confocal microscopy (RCM) are extremely helpful tools in the diagnosis of AM. Histopathologically, there is an attenuation or complete absence of melanin granules, and immunohistochemistry for melanocytic markers, such as S100, Melan-A, HMB-45, may be necessary for accrate diagnosis. Like other types of melanomas, the Breslow depth, presence or absence of ulceration, and mitotic rate are necessary for diagnosis, staging, and management. The standard of treatment for AM includes surgical excision with margins based on staging with sentinel lymph node biopsy if indicated. We present the clinical and histopathological features, special techniques, differential diagnoses, and current management of amelanotic melanoma.