The Significance of Melan-A–Positive Pagetoid Melanocytosis in Dysplastic Nevi

Abstract

Dysplastic nevi may occasionally display alarming histological features. One of these features is the presence of upward spread of melanocytes (pagetoid melanocytosis), identified either on routine histologic sections or after immunohistochemistry using one of the melanocytic markers. Forty-three cases of dysplastic nevi with mild to moderate atypia were selected and retrieved, and Melan-A staining was performed. Melan-A-positive cells with pagetoid architecture were present in 27 cases (63%). Of these, only 5 cases demonstrated pagetoid architecture on routine staining. It is concluded that Melan-A staining should be used only with caution as an adjunct to routine histology in the evaluation of dysplastic nevi with mild to moderate atypia because the identification of pagetoid melanocytosis using this technique has the potential to lead to an erroneous diagnosis of melanoma.

Staining pattern of specific and cross‐reacting Melan‐A antibodies: A comparative study on 15,840 samples from 133 human tumor types

“…Published Melan-A positivity rates are considerably discordant for various tumor entities. For example, the fraction of positive tumors varies from 4% to 100% in benign nevi [8][9][10][11][12][13][14][15][16][17][18][19][20], 69%-100% in primary malignant melanoma [8-11, 13, 17, 19-33], 0%-33% in desmoplastic melanoma [8,10,11,17,20,23,31,33], 50%-81% in lymph node metastases of malignant melanoma [13,27], 50%-100% in adrenocortical carcinoma [11,[34][35][36][37][38][39], 68%-100% in adrenocortical adenoma [11,35,37,38], 50%-100% in renal angiomyolipoma [40][41][42][43][44], 0%-20% in leiomyosarcoma [10,11,25], 0%-25% in breast cancer [5,25,35,45], 0%-17% in renal cell carcinoma…”

“…Published Melan‐A positivity rates are considerably discordant for various tumor entities. For example, the fraction of positive tumors varies from 4% to 100% in benign nevi [8–20], 69%–100% in primary malignant melanoma [8–11, 13, 17, 19–33], 0%–33% in desmoplastic melanoma [8, 10, 11, 17, 20, 23, 31, 33], 50%–81% in lymph node metastases of malignant melanoma [13, 27], 50%–100% in adrenocortical carcinoma [11, 34–39], 68%–100% in adrenocortical adenoma [11, 35, 37, 38], 50%–100% in renal angiomyolipoma [40–44], 0%–20% in leiomyosarcoma [10, 11, 25], 0%–25% in breast cancer [5, 25, 35, 45], 0%–17% in renal cell carcinoma [5, 25, 35, 38, 46, 47] and 0%–100% in ovarian carcinomas [5, 35, 48–51]. Variable antibody properties, different staining protocols, and varying criteria for defining positivity may have caused these divergent data.…”