Pigmented Neoplasms and Nevi



Pigmented Neoplasms and Nevi


Ka Yee Kung

Henry Hin Lee Chan



BACKGROUND

Pigmented neoplasms and nevi are common dermatological conditions that dermatologists encounter frequently in daily practice. Although some patients are concerned about the associated health risk, most request the removal of these lesions for cosmetic purposes. Lasers have been used successfully for the treatment of pigmentary conditions, and although some lesions such as nevi of Ota respond very well to laser treatment, others such as café au lait macules are much less responsive. The use of lasers in the treatment of congenital melanocytic nevi is more controversial.


CAFÉ AU LAIT MACULES


PRESENTATION

Café au lait macules (CALMs) present as sharply demarcated light to dark brown hyperpigmented patches, often presenting in early infancy. The presence of multiple
CALMs should signal a workup for neurofibromatosis (NF) 1. In the newborn period, NF1 presents with pseudoarthroses, congenital glaucoma, and sphenoid wing dysplasia. In early childhood, NF1 presents with embryonal tumors, compression injuries characterized by back pain in the presence of CALMs, and optical gliomas by the age of 3 years. NF2 typically presents in middle age with acoustic neuromas, although CALMs may also be present.



PATHOGENESIS

The etiology of CALMs is not known; however, Ras pathway disturbances seem to underlie the pathogenesis of CALMs. In NF1, an autosomal dominant disorder, the mutation is in the neurofibromin gene, which encodes a GTPase activating protein that downregulates p21-ras expression. In half of the cases, the mutation is spontaneous. NF2 is also autosomal dominant and due to a mutation in neurofibromin 2 or merlin, which encodes a cytoskeletal protein and acts as a tumor suppressor protein. Studies have shown that the neurofibromin tumor suppressor is involved in regulating melanogenesis via protein kinase A-ERK signaling, which in turn regulates MITF and other melanogenesis signaling pathways.2


Jun 29, 2020 | Posted by in Dermatology | Comments Off on Pigmented Neoplasms and Nevi
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