CASE REPORT   

Giornale Italiano di Dermatologia e Venereologia 1999 December;134(6):613-8

Copyright © 1999 EDIZIONI MINERVA MEDICA

language: Italian

Spitz nevus with plexiform architecture

Castelli E. ¹, Pistone G. ¹, Wollina U. ², Lanzarone A. ¹

¹ Università degli Studi - Palermo, Istituto di Clinica Dermosifilopatica, Cattedra di Clinica Dermatologica; ² Friedrich-Schiller-Universität Jena, Klinik für Hautkrankheiten

Spitz nevus is a benign melanocytic aggregate, cytologically characterized by atypical spindle and/or epithelioid nevus cells with the possible presence of multinucleated bizarre cells. Its picture includes clinical and histologic variants, which in the last few years have been added to the original form. In the present study, a case with a singular plexiform pattern in a 14 year old female patient is reported. Histologically, the lesion appears as a well delimited, symmetrical, endo-exophytic nodule, composed by epithelioid and spindled atypical nevus cells, with an admixture of ganglion-like and Touton-type bizarre cells. The nevus is compound, and its intradermal portion consists of large lobules separated by incomplete fibrous septa, as it can be seen when a convoluted structure is observed in section. Melanin is hardly detectable in the newly formed tissue, which is diffusely positive to S100 protein and NKI/C3 antibodies, while HMB45 and bcl-2 protein are mainly expressed by its junctional component. Based on the histologic and immunohistologic findings the lesion can be considered as a variant of Spitz nevus with plexiform architecture, while the absence of heavily pigmented, bipolar, dendritic melanocytes can exclude the diagnosis of combined Spitz-plus-plexiform cellular blue nevus.