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Giornale Italiano di Dermatologia e Venereologia 2020 April;155(2):173-8

DOI: 10.23736/S0392-0488.17.05723-6


language: English

The variegated histopathological features of atypical lentiginous melanocytic nevi: a single institution experience

Alessia BARISANI 1 , Salvatore D. INFUSINO 1, Cosimo MISCIALI 1, Beatrice PASSARINI 2, Nunzio C. SALFI 3, Elisa VAROTTI 1, Annalisa PATRIZI 1

1 Unit of Dermatology, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; 2 Laboratory of Dermatopathology, Department of Dermatology, University of Bologna, Bologna, Italy; 3 Department of Pathological Anatomy and Histopathology, University of Bologna, Bologna, Italy

BACKGROUND: Atypical lentiginous melanocytic nevi (ALMNs) are atypical pigmented lesions with histopathological features similar to those of dysplastic nevi, with a lentiginous pattern. Variable histopathological features of ALMNs were observed in our practice.
METHODS: We described the histopathological features of ALMNs diagnosed in the period 2009-2015. Our cases were divided into 2 groups: Group 1: ALMNs showing the same histopathological features as previously described in the literature; Group 2: ALMNs with different features.
RESULTS: Twenty-nine ALMNs were diagnosed; 2 groups of ALMNs were identified. Group 1 ALMNs showed a constant, mild epidermal acanthosis; frequently, an inflammatory infiltrate and dermal fibrosis, cytological atypia and mild architectural atypia. Group 2 ALMNs showed a constant psoriasis-like acanthosis with a hypercellularity of the rete ridges; cytological atypia was rare, whereas architectural atypia was constantly observed. Immunohistochemistry (MART-1 staining) revealed that the melanocytes were localized at the dermo-epidermal junction in both groups. ALMNs showed a broad spectrum of histopathological features.
CONCLUSIONS: Our main finding was a constant architectural atypia in all lesions of Group 2. The identification of a unique type of ALMN seems no longer possible. The correct recognition of such benign, though atypical, melanocytic lesions is important in order to avoid an overdiagnosis of cutaneous melanoma and to prevent their potential evolution to the latter.

KEY WORDS: Dysplastic nevus syndrome; Melanoma, cutaneous malignant; Cytology

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