A collection of blue papules

Abstract

Conflict of interest: none declared. A 76‐year‐old man presented with a 3‐month history of three asymptomatic blue ‘spots’ on the left chest. There was no other medical history of note. Skin examination showed three dark‐blue papules clustered above the left nipple (Fig. 1). Physical examination was normal and there was no lymphadenopathy or hepatosplenomegaly. ... Sections of a 4‐mm punch biopsy taken from one of the papules Haematoxylum and eosin stained showed a heavily and coarsely pigmented intradermal melanocytic naevus (Fig. 2a). Elongated dendritic cells and plump melanocytes were present (Fig. 2b). Only a few cells contained prominent nucleoli. No mitotic figures were seen. These findings were duplicated on histopathological analysis of the excised specimen. ... What is your diagnosis? Papular plaque‐type blue naevus. Blue naevi usually exist in common, cellular or combined forms. The common blue naevus is a small blue‐black papule, usually located on the dorsa of the feet or hands, and characterized histologically by the presence of clumped dendritic melanocytes in mid to lower dermis. The cellular blue naevus is a similar but larger lesion on the sacrococcygeal region or the buttocks and histologically differs from the common blue naevus by the presence of large, pale, spindle‐shaped cells in addition to the dendritic melanocytes. Malignant degeneration has been reported in cellular blue naevus but is rare in common blue naevus. Combined blue naevus is so termed as it shares the histological features of the common blue and naevocytic naevus. Other varieties of blue naevi are also described.