Recurrent melanocytic nevus: a histologic and immunohistochemical evaluation.
BACKGROUND
Recurrent melanocytic lesions may histologically resemble malignant melanoma.


METHODS
We evaluated the original nevi (ON) and recurrent nevi (RN) of 15 patients by routine histology and immunohistochemistry (IHC), examining expression of S-100 protein, gp100 (with HMB-45), MART-1, tyrosinase, and the Ki-67 proliferation marker.


RESULTS
Compared with ON, RN had a dermal scar, a significantly greater number of melanophages, and a greater extent of cellular atypia including prominent nucleoli and larger cell size. Architecturally, RN showed significantly less symmetry than ON; however, the percentage of junctional cohesive nests, the presence of suprabasal spread, and the degree of confluence were similar between ON and RN. Both ON and RN showed a decrease in expression of gp100 and tyrosinase with increasing depth ("maturation gradient") and low proliferative activity in both the junctional (4.6% for ON vs. 4.13% for RN) and the dermal components (0.93% for ON vs. 1.45% for RN).


CONCLUSIONS
RN exhibit a dermal scar, a greater number of melanophages, cytologic atypia, and asymmetry than ON, features that may raise concern about the possibility of malignant melanoma. However, the area with the irregular architectural pattern is restricted to the epidermis and dermis immediately above the scar. In addition, IHC helps to distinguish RN from malignant melanoma; specifically, RN demonstrate an immunohistochemical "maturation pattern" (with HMB-45 and anti-tyrosinase) and a low proliferative index (with Ki-67).
Hoang
M P
MP
Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Prieto
V G
VG
Burchette
J L
JL
Shea
C R
CR
D000293:Adolescent; D000328:Adult; D000951:Antigens, Neoplasm / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D002648:Child; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000032:analysis; D058965:MART-1 Antigen; D008297:Male; D008544:Melanocytes / Q000737:chemistry / Q000473:pathology; D058950:Melanoma-Specific Antigens; D008562:Membrane Glycoproteins / Q000032:analysis; D014442:Monophenol Monooxygenase / Q000032:analysis; D009363:Neoplasm Proteins / Q000032:analysis; D009364:Neoplasm Recurrence, Local; D009508:Nevus, Pigmented / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D009418:S100 Proteins / Q000032:analysis; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D058951:gp100 Melanoma Antigen
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D058965:MART-1 Antigen; C548667:MLANA protein, human; D058950:Melanoma-Specific Antigens; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D009418:S100 Proteins; D058951:gp100 Melanoma Antigen; D014442:Monophenol Monooxygenase