Solitary Mastocytoma Successfully Treated with a Moderate Potency Topical Steriod

We report a case of solitary mastocytoma in a child which was successfully treated with a topical steroid of moderate potency. The patient was an 18-month-old girl who presented with localized oval shape yellowish to hyperpigmented lesion on the medial aspect of her right forearm noticed accidentally by the parents since the age of 6 months. The lesion was observed to get urticated mainly after bathing, toweling, and scratching of the area, associated with reddening and itching confined to the lesion (Figure 1). No other area of the body was affected with any similar lesion.

Examination of the skin revealed a yellow-tan oval shape patch 1 x 3 cm in diameter which was firm to the touch with intact overlying skin. The lesion became swollen and itchy when it was rubbed vigorously (positive Darier’s sign). Systemic examination was unremarkable. The patient investigations including complete blood count, routine biochemical data, plasma histamine level, and urinalysis were within normal levels. Skin biopsy was cancelled because the parents refused, so our clinical diagnosis was solitary mastocytoma even though it was not confirmed histologically. We started the patient on a moderate potency corticosteroid (betamethasone valerate 0.1% cream) twice a day for six weeks after which the lesion became softer with a weak Darier’s sign. This treatment was continued for another four months which led to resolution of the lesion with residual hyperpigmentation, negative Darier’s sign, and no signs of atrophy (Figure 2). Follow up of the patient for another 8 weeks without treatment did not reveal any recurrence of the lesion.