A 4-year-old boy presented with multiple hypo- pigmented patches over his whole body (Fig. 1). 18 months ago, they started as small hypopigmented macules over the chest and gradually increased in number and size and spread to the entire body. The lesions were asymptomatic and were accentuated with sun exposure. There was no fluorescence under Wood’s light. On physical examination, the lesions were symmetrically distributed over the whole body and consisted of large hypopigmented patches with indistinct borders. Laboratory examinations, including chest PA, CBC, LFT, and UA were within normal limits. Potassium hydroxide (KOH) mount from a hypopigmented lesion was negative. The boy had a history of xesosis for 2 years but no family history of extensive pityriasis alba or atopic dermatitis.
Fig. 1. Multiple hypopigmented, non-scaling, and non- coalescing patches with indistinct borders involving the whole body.
Histopathological examination of the hypopig- mented patch revealed hyperkeratosis, acanthosis in the epidermis, and perivascular inflammatory cells infiltration in the upper dermis (Fig. 2A). On immunoperoxidase staining, the irregularly distributed melanocytes in the basal layer were positive for S-100 protein (Fig. 2B). Although the patient was treated with topical steroid twice a day for 1 month, no regression of the lesions were observed.
Fig. 2. (A) Histologic examination of the hypopigmented patch revealed hyperkeratosis, focal spongiosis in the epidermis and perivascular inflammatory infiltration (H&E, x200). (B) Irregularly distributed melanocytes were positive for S-100 protein in the basal layer (S-100 protein, x200).