P2.M246: On the Dot; Repetitive Episodes of Urticaria in a Neonate on Total Parenteral Nutrition (TPN).

Introduction: Isolated urticaria is not uncommon in pediatrics but rarer in infants with their immature immune systems and limited epitope exposure. Identifying the cause of urticaria can be difficult; while frequent triggers include viral infection, medications such as antibiotics, or food allergens, these possibilities are not always immediately apparent and can be simultaneously present. More unusually, infants have been documented to have hypersensitivity to parenteral nutrition in at least two cases.

Case Description: An infant with prenatally diagnosed omphalocele was delivered vaginally at 36w6d to a G2P0 mother. He was found to have significant cloacal exstrophy and ruptured bowel and was immediately intubated and taken to the OR, where a silo was placed. He initially received IV fluids before transitioning to TPN on day of life (DOL) 3. He remained in the NICU undergoing treatment for omphalocele-exstrophy-imperforate anus-spinal defect complex (OEIS) and renal anomalies. On DOL 13, he developed a blotchy, erythematous maculopapular rash with raised centers that began on his trunk and limbs and rapidly coalesced over his entire body. The rash resolved within 10-20 minutes without airway involvement or other signs of anaphylaxis. DOL 14 the same reaction appeared at the same time of day, observed to occur about 30 minutes after his daily change of fluids and medications. It resolved with diphenhydramine. As the urticaria was chronologically linked to starting infusions of dexmedetomidine, fentanyl, TPN and lipid emulsion, each element was delayed in turn to isolate the trigger. On DOL 16, he was given TPN without trace elements and had no reaction. With the continuing exclusion of trace elements, he tolerated his fluid changes. Enteral feeds of complete formula were introduced, protecting against nutritional deficiency, and have been tolerated without reaction.

Discussion: While some case studies report hypersensitivity to the osmolality of TPN and IgE-mediated response is less likely in an infant, cessation of urticaria episodes with removal of trace elements strongly indicates a causal link. Trace elements is a catch-all term for metal cofactors and other mi-nor nutrients essential to the human body – suggesting they are an unlikely agent to provoke hypersensitivity - but trace elements as part of TPN have been known to cause similar urticaria in other age groups. While this is the first such case reported for infants, there are reports of multivita-mins and lipid emulsions causing similar skin reactions.

Conclusion: This infant’s routine urticaria episodes stopped when his trace elements were discontinued. Since recurrent urticarial lesions have also been reported in a gastroschisis patient receiving TPN and our patient had bladder exstrophy and ruptured omphalocele, we question if externalization of internal organs increases the risk of cutaneous hypersensitivity in similar patients. Knowledge and removal of these suspected allergens may allow TPN delivery without compromising nutrition.