CROSS-REACTIVITY CONCERNS: CASHEW-ALLERGIC PATIENT'S ANAPHYLACTIC REACTION TO MILK-BASED YOGURT

Patients with cashew allergy may be at risk for allergic reactions to foods containing citrus pectin. This case describes a reaction to pectin-containing yogurt in a 7-year-old with cashew allergy. One week after passing a liquid milk challenge, a 7-year-old male with a past history of peanut, tree nut, wheat, egg and milk allergies developed anaphylaxis immediately after eating a milk-based yogurt. Upon ingestion of the yogurt, he developed immediate coughing, throat clearing, and hives. His mother was concerned that he was having a reaction to milk, even though he had been tolerating other brands of milk-based yogurt and uncooked liquid milk each day since the milk oral food challenge (OFC). Examination of ingredients in the suspect yogurt brand revealed that the yogurt contained fruit pectin. The patient was instructed to retry a pectin-free yogurt, and he continued to tolerate milk without reaction. Anaphylaxis to fruit pectin has been described in cashew allergic patients in several case reports. Both the citrin protein in citrus seeds and cashew antigen Ana o 2 are 11S globulins belonging to the cupin superfamily, and there is significant homology between the two proteins. Co-sensitization is thought to occur in 50-70% of cashew allergic patients; however, rates of true allergy are likely much lower. Nonetheless, fruit pectin should be considered as a culprit in patients with unexplained anaphylaxis, especially in those with a known cashew allergy.