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Context.-Atypical lentiginous melanocytic lesions, particularly in older individuals, continue to pose a diagnostic challenge. Such lesions often show features intermediate between lentiginous nevus and melanoma in situ. We have recently defined within this group of lesions a histologic pattern of lentiginous melanoma, a slowly progressing variant of melanoma typically found on the trunk and proximal extremities of middle-aged and older individuals.
Objective.-To review the clinical and histologic features of lentiginous melanoma and its histologic differential diagnosis.
Data Sources.-Review of pertinent published literature and work in our laboratory.
Conclusions.-Lentiginous melanoma defines a subset of slowly progressing melanoma occurring in middle-aged and older patients. It is histologically characterized by a broad atypical lentiginous growth pattern of moderately atypical melanocytes showing focal nesting and pagetoid spread without significant dermal fibroplasia or alteration of the rete ridges. Lentiginous melanoma shows significant overlap in clinical and histologic features with atypical lentiginous nevus (of the elderly). Relationship between these entities requires further investigations. Given the risk of progression to invasive melanoma, all lesions showing features of lentiginous melanoma should be treated with adequately wide excision.
(Arch Pathol Lab Med. 2011;135:337-341)
The histopathologic recognition of early cutaneous melanoma is to a large extent based on the presence of an atypical lentiginous proliferation of melanocytes along the dermoepidermal junction. This may occur in atrophic sun-damaged skin, such as that seen in lentigo maligna, or in addition to prominent pagetoid spread, as seen in superficial spreading melanoma. In acral sites, there may be a lentiginous proliferation of atypical melanocytes without much pagetoid spread and preservation of the epidermal pattern. Mixed patterns of intraepidermal melanocytic proliferation occur in some melanomas, and there are melanomas that cannot be easily classified into the traditional groupings of lentigo maligna, superficial spreading, or acral lentiginous types. We coined the term lentiginous melanoma to describe what we believed to be a subset of melanomas, usually present in older adults, but also found in middle-aged persons, and in limited biopsies histologically bearing superficial resemblance to lentiginous nevus or atypical (dysplastic) lentiginous nevus of the elderly.1-3 Similar clinicopathologic findings were noted in a subsequent article by Davis and Zembowicz.4 Awareness of this entity, together with examination of the entire lesion, will aid in achieving the correct diagnosis.
CLINICAL FINDINGS
Lentiginous melanomas...