A 2-year-old girl was referred to the dermatology clinic by her pediatrician because of unsuccessful treatment of presumed seborrheic dermatitis. She presented with a 4-month history of an erythematous, pruritic, “scaly” rash on her scalp and a red-brown nodule behind her right ear. Her medical history was remarkable only for urticaria pigmentosa, which was stabilized on a regimen of loratadine, and her family history was noteworthy for large cell lymphoma in her half-brother. A review of systems disclosed no other symptoms or abnormalities.