Syringotropic Melanoma: A Variant of Melanoma With Prominent Involvement of Eccrine Apparatus and Risk of Deep Dermal Invasion
Department of Pathology, Harvard Vanguard Medical Associates, 133 Brookline Avenue, Boston, MA 02215, USA.The American Journal of dermatopathology (Impact Factor: 1.39). 01/2012; 34(2):151-6. DOI: 10.1097/DAD.0b013e318227c90d
We report 7 cases which can be regarded as a syringotropic melanoma-a unique presentation of melanoma defined as melanoma spreading within the eccrine apparatus into the reticular dermis and/or subcutaneous tissue deeper than any (if present) associated invasive melanoma. Six patients were females, and 1 was a male. Their ages ranged from 32 to 85 years old (average 63). The lesions showed a wide site distribution, occurring on the extremities (4), trunk (2), and head and neck (1). Five melanomas were superficial spreading type; 1 was acral lentiginous type; 1 was unclassified. Four lesions (57%) invaded from within eccrine apparatus at a depth and anatomical level greater than that of an adjacent conventional invasive melanoma arising from the surface epidermis. In 1 lesion, which presented clinically as a pigmented macule, deep dermal syringocentric invasive tumor was the only site of invasion and tumorigenic growth. Thus, this variant of melanoma carries a significant risk of syringocentric deep dermal invasion, which may be unsuspected clinically but must be detected on histological examination to provide the most accurate prognosis and staging information.
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ABSTRACT: Determination of the niche for early-stage cancer remains a challenging issue. Melanoma is an aggressive cancer of the melanocyte lineage. Early melanoma cells are often found in the epidermis around sweat ducts of human volar skin and the skin pigmentation pattern is an early diagnostic sign of acral melanoma. However, the niche for melanoma precursors has not been determined yet. Here we report that the secretory portion (SP) of eccrine sweat glands provide an anatomical niche for melanocyte-melanoma precursor cells. Using lineage-tagged H2B-GFP reporter mice, we found that melanoblasts which colonize sweat glands during development are maintained in an immature, slow-cycling state but renew themselves in response to genomic stress and provide their differentiating progeny to the epidermis. FISH analysis of human acral melanoma expanding in the epidermis revealed that unpigmented melanoblasts with significant CyclinD1 gene amplification reside deep in the SP of particular sweat gland(s). These findings indicate that sweat glands maintain melanocyte-melanoma precursors in an immature state in the niche and explains the preferential distribution of early melanoma cells around sweat glands in human volar skin.This article is protected by copyright. All rights reserved.
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