The stars within the melanocytic garden: Unusual variants of Spitz naevi

Background Spitz naevi may present a wide spectrum of morphologies. Histopathologically, many variants, including desmoplastic, angiomatoid, verrucous/polypoid, plexiform, pagetoid, halo, myxoid, granulomatous and tubular Spitz naevi have been described. Clinical and dermoscopic features of these unusual variants of Spitz naevi have been reported only rarely. Objectives The aim of this study is to describe clinical, dermoscopic and histopathological features of uncommon morphological variants of Spitz naevi in order to raise awareness among clinicians about their peculiar patterns of presentation. Methods We searched our image database retrospectively from 2004 to 2014 for images of excised tumours using Spitz/Reed naevus as a keyword. Results A total of 307 excised skin lesions with a histopathological diagnosis of Spitz/Reed naevus were found. Among those we identified 13 uncommon variants of Spitz naevi including six cases of desmoplastic Spitz naevus, five cases of angiomatoid Spitz naevus and two cases of verrucous Spitz naevus. These lesions did not fulfil the already described dermoscopic criteria of Spitz naevi, with the exception of angiomatoid Spitz naevi, exhibiting a pinkish background and dotted vessels in dermoscopy. Desmoplastic Spitz naevi may be difficult to differentiate from dermatofibroma clinically, and from melanoma under dermoscopic examination. Verrucous Spitz naevi, despite their relatively unusual clinical features, show reassuring morphological clues histologically, which allows the differential diagnosis from an atypical spitzoid tumour. Conclusions In all cases an atypical melanocytic lesion could not be excluded under dermoscopy, thus warranting excision and histopathological examination. What's already known about this topic? Spitz naevi may present a wide spectrum of morphologies. Clinical and dermoscopic features of unusual variants of Spitz naevi have been reported only rarely. What does this study add? We describe clinical, dermoscopic and histopathological features of uncommon morphological variants of Spitz naevi, in order to raise awareness among clinicians about their peculiar patterns of presentation.