Atypical junctional melanocytic proliferations in benign lichenoid keratosis.
Melanocytic lesions with lichenoid regression may mimic a benign lichenoid keratosis (BLK) histologically. A total of 336 BLKs were reviewed and deeper sections obtained to determine the frequency of this phenomenon. Two cases (0.6%) showed at least 1 melanocytic nest or junctional multinucleated melanocyte (starburst melanocyte) on deeper sections confirmed by MART-1 immunostaining. Both of these cases demonstrated solar elastosis, and 1 case had an effaced rete ridge pattern. Not included in the histological study are 5 additional cases in which the initial slide showed only lichenoid dermatitis, but deeper sections obtained before to the initial sign-out revealed a melanocytic proliferation. These 5 cases would have been signed out as "consistent with BLK" if deeper sections had not been obtained. Fluorescent in situ hybridization (FISH) was performed on 3 cases; in each case, the melanocytes demonstrated a loss of chromosome 9p21 DNA copy number. The finding of nests of genetically altered melanocytes on severely sun-damaged skin strongly suggests that these cases represent lichenoid regression of melanoma in situ. Pathologists should approach a diagnosis of BLK cautiously in the setting of severely sun-damaged skin.
Dalton
Scott R
SR
Department of Pathology, Brooke Army Medical Center, Fort Sam Houston, Texas, USA.
Fillman
Eric P
EP
Altman
Coleman E
CE
Gardner
Timothy L
TL
Davis
Thomas L
TL
Bastian
Boris C
BC
Libow
Lester F
LF
Elston
Dirk M
DM
D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism; D002278:Carcinoma in Situ / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002899:Chromosomes, Human, Pair 9; D004247:DNA / Q000032:analysis; D003937:Diagnosis, Differential; D018628:Gene Dosage; D015726:Giant Cells / Q000473:pathology; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D017404:In Situ Hybridization, Fluorescence; D008010:Lichen Planus / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D058965:MART-1 Antigen; D008544:Melanocytes / Q000378:metabolism / Q000473:pathology*; D008548:Melanosis / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D011230:Precancerous Conditions / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D013472:Sunlight / Q000009:adverse effects
D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D004247:DNA