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Superficial basal cell carcinoma: Dermoscopic and histopathological features of multiple small erosions

tation and pigment incontinence with an absence of naevus cells. The second is a 41-year-old Chinese woman who presented for management of dermatographism. There was an incidental finding of a blaschkoid pigmented rash in the left inguinal region (Fig. 2). This rash began 25 years previously and was slowly progressing. A skin punch biopsy from the left inguinal region showed epidermal acanthosis, prominent basal layer pigmentation and pigment incontinence (Fig. 3). Both cases fulfil the criteria for PCZH described by Rower and colleagues. Differential diagnoses were considered including linear lichen planus, linear fixed drug eruption and post-inflammatory hyperpigmentation. However, no initial inflammatory insult was described and histopathology revealed an absence of lichenoid inflammation. The clinical presentation of PCZH is asymptomatic cribriform macular pigmentation distributed along the lines of Blaschko. This distribution suggests somatic mosaicism and it has been proposed that this disorder is a late onset, localised form of linear and whorled naevoid hypermelanosis. The trunk is the most commonly reported site and multifocal disease has been described. The mean age of onset was 14 years in one series. The histological differential diagnosis includes linear and whorled naevoid hypermelanosis, confluent and reticulated papillomatosis, acanthosis nigricans and Becker’s naevus. The largest review of pathological findings in PCZH reported pigment incontinence in 13 of 30 cases. Biopsy findings for our second case included epidermal acanthosis, which has been seen in other cases and could be considered an additional histological finding in this disorder. PCZH is a distinctive disorder and may be a spot diagnosis for the informed physician and dermatopathologist, illustrating the value of clinicopathological correlation in skin disease.