Spotted grouped pigmented naevus type I

An 11-year-old boy had an asymptomatic non-progressive hyperpigmented lesion on the extensor aspect of the left arm since birth. Examination showed multiple, grouped hyperpigmented 1–3 mm papules forming a well-defined 10 × 4 cm plaque [Figure 1]. Dermoscopy showed multiple blackish-brown papules in a globular pattern with interspersed normal skin [Figure 2].

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Figure 1:

Grouped hyperpigmented papules forming a well-defined plaque.

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Figure 2:

Reticulo-globular pattern with intervening normal skin seen on dermoscopy.

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Spotted grouped pigmented naevus is a rare type of congenital melanocytic naevus characterised by naevus cell proliferation around the skin appendages. Three types of spotted grouped pigmented naevus are: type I (plaque type), type II (agminated naevus) and type III (naevus spilus). The possibility of basaloid follicular hamartoma was excluded based on the close grouping of the papules, the black (rather than brown) colour of the papules, the absence of milia-like or comedone-like lesions and the absence of hypotrichosis and hypohidrosis.