Histological evolution of lentiginous melanoma: a report of five new cases.
BACKGROUND
The term lentiginous melanoma was recently used for atypical melanocytic proliferations sharing some histological features with lentigo maligna and associated with a protracted in situ stage before invasion. Lentiginous melanoma was characterized by predominantly single-cell lentiginous growth pattern with focal junctional nests and pagetoid spread, preservation of the dermoepidermal junction, limited cytological atypia, and lack of significant solar elastosis. We report five similar cases.


METHODS
Histological review of routine sections with clinicopathological correlation.


RESULTS
Three patients were male and two were female. The age at presentation ranged from 24 to 66 years. All lesions arose on the truck or proximal extremities. All five cases fulfilled histological criteria proposed for lentiginous melanoma. None of the lesions showed significant solar elastosis. One lesion was followed clinically and histologically for 16 years without intervening treatment. It had three local recurrences before culminating in invasive melanoma.


CONCLUSIONS
Our observations support recent efforts to distinguish lentiginous melanoma as a distinct clinicopathological entity. Lentiginous melanoma can remain in situ for a long time before invasion and may be considered an analogue of lentigo maligna occurring on non-severely sun-damaged skin. Familiarity with the histological features of this variant is important for its early recognition and treatment.
Davis
Tracy
T
Department of Pathology, Massachusetts General Hospital and Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
Zembowicz
Artur
A
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D018327:Hutchinson's Melanotic Freckle / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D009508:Nevus, Pigmented / Q000473:pathology; D011230:Precancerous Conditions / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*