Bashful rash on a baby's cheek

You are in the middle of a busy day in the pediatrics outpatient care center, with appointments scheduled cheek by jowl. So it's only during a break that you're able to return the telephone call of a mother who had called earlier. This is a family you've known for the past year, since the birth of their first child, a boy. You recall that the mother was always pleasant and perceptive, and asked thoughtful, pertinent questions about her baby, who would now be 11 months old, you gauge.

You reach her at home, and she promptly tells you, "I think my son has a food allergy." You hear no anxiety or alarm in her voice as she explains.

"Over the past few days he's been breaking out in a rash when he eats his food," she says. "It was occasional at first, but it's more frequent recently."

You ask about the location of the rash: It's restricted to the right side of his face, she tells you. What about associated symptoms-pruritus, pain, excessive salivation, swelling of facial structures, a rash elsewhere? She hasn't noted any of these.

Last, she explains that the rash disappears 15 to 30 minutes after it appears, without any residuum, and that, between episodes, the baby is his normal self.

Knowing that you saw the baby two months ago for a well-child visit-at which time everything was perfectly normal-and thinking that these episodes do not seem severe, you recommend that she continue to observe the boy and keep a record of additional episodes.

A few days later, however, you learn that the mother has made an appointment to have you see her son.

Now Mom sees it, now you don't

The baby, looking happy and healthy, and his mother come to the clinic the following week. She tells you that the episodes of rash have recurred in almost the same pattern that she described to you during your telephone conversation. Again, the rash comes on often but not predictably with every feed. You take a history but elicit no other symptoms and no family history of allergy or atopy. The patient has not taken any local or oral medications, has not worn any new clothes, and hasn't been exposed to any new soaps or other toiletries or cosmetics.

The baby is developmentally normal and up to date with routine immunizations. Again, the mother emphasizes that the phenomenon occurs mostly when he is eating solid food.

The medical record shows that most prior visits have been for routine health maintenance. Only one visit gets your attention: When the boy was about 10 days old, his parents brought him to the clinic because they were concerned about "small lumps" on the face. You were out, so one of your colleagues saw the patient that day and, in the chart, described the lesions as "about 1 cm in diameter with a bluish hue." One lesion was on the left cheek; two others, at the angle of the jaw on the right side of the face. Noting that delivery had been by forceps, your colleague was confident that the lesions represented subcutaneous fat necrosis.

The parents were reassured by this diagnosis, and the lesions did resolve in a few days. On a subsequent visit, no lesions were palpable.

Your examination today is unremarkable: No rash to be seen, skin over the area not dry or warm, no difference between the two cheeks. No facial asymmetry or swelling, no palpable glands or nodes. Mouth and pharynx are normal. You observe that, even though the boy has been drinking formula from a bottle during the visit, this activity has not provoked a rash. Regrettably, he isn't interested in eating anything at this time.