A 3-month-old boy presented with a lesion over the scalp for a week. Examination revealed a well-defined patch with a greasy surface, and scaling on the top of the lesion. It was surmounted by thick yellow-brown crust (Fig. 1). Axillae, groins and other areas of the body were free from any lesions; nails and mucosae were normal. A diagnosis of cradle cap was made and ketoconazole shampoo was prescribed.

Fig. 1 Well-defined lesion on scalp covered with crust.

Cradle cap is a type of seborrheic dermatitis, exclusively affecting infants; more commonly within first 6 weeks of life. It usually presents as asymptomatic thick, crusty, yellow-brown patches. Fungal infection (Malassezia furfur) and overactive sebaceous glands are implicated in the pathogenesis. The condition clears off as the baby grows older. Treatment consists of removal of crusts with 3% salicylic acid; and application of low-potency steroids and antifungal agents. Clinical differentials include tinea capitis (easy pluckability of hairs), atopic dermatitis (presence of pityriasis alba, positive family history), impetigo (honey colored crust), and psoriasis (scaly erythematous plaque with involvement of other sites and nails).