Purpuric phototherapy-induced eruption in transfused neonates: relation to transient porphyrinemia.

OBJECTIVE: Blue light phototherapy is commonly administered to neonates as treatment of indirect hyperbilirubinemia, often in conjunction with blood transfusions to treat hemolytic anemia. We observed a distinctive cutaneous complication of phototherapy in six neonates with hyperbilirubinemia.

METHODOLOGY: We studied the clinical and histologic characteristics of the eruption, as well as the porphyrin levels in affected neonates. Five of the patients had erythroblastosis fetalis; the other had profound anemia from twin-twin transfusion. All of the neonates developed purpuric patches at sites of maximal exposure to the phototherapy lights, with dramatic sparing at shielded sites within 24 hours after initiation of the phototherapy. On discontinuation of phototherapy, all eruptions cleared within 1 week. Examination of skin biopsy sections showed purpura without significant inflammation or keratinocyte necrosis. Plasma porphyrins (copro- and proto-) were elevated in the two patients in which they were assessed.

CONCLUSIONS: The distribution of the eruption in areas exposed to light and presence of circulating porphyrins suggest that porphyrinemia may underlie the light-induced purpuric eruption. Additional studies will be required to determine definitively the mechanisms of both the purpuric phototherapy-induced eruption and the development of increased blood porphyrin levels in these transfused neonates.