Cooked potato (Solanum tuberosum) is one of the first solid foods in a child's diet and is considered to be safe, although a European questionnaire-based study at 17 clinics from 15 cities found potato to be the 25th most prevalent cause of self-reported allergic symptoms [1]. Potato is also used to make emollients and cleansing masks.Allergic reactions to raw and cooked potato have multiple clinical presentations. In sensitized individuals, handling raw potato can induce immediate IgE-mediated manifestations, namely, respiratory involvement and contact dermatitis. Ingestion of cooked potato can trigger both immediate and late reactions, such as chronic eczema flares; there are reports of anaphylaxis following exposure to this tuber [2,3].A 2-year-old white boy was referred to our allergy department with a history of lip edema and surrounding erythema a few minutes after ingestion of his first soup (made of potato, carrot, and pumpkin) when he was 4 months old. No respiratory, gastrointestinal, or cardiovascular signs or symptoms were reported. After the initial episode, the same clinical picture was triggered every time the child ate the same soup, with complete and spontaneous resolution of symptoms between episodes. The child's mother sequentially withdrew each ingredient from the soup, eventually realizing that symptoms were elicited by the ingestion of potato. After a similar reaction when hen egg was introduced, a strict potato and egg avoidance diet was started, and the symptoms resolved. The remaining foods were introduced without further reactions. The child had previously undergone orchidopexy.The physical examination was normal, and skin prick tests to aeroallergens and latex extracts (Leti) were negative. Given the relatively long duration of the avoidance diet, we first performed additional prick-to-prick tests with raw and cooked potato. The results were positive to raw potato (at 2 and 4 years of age). The ImmunoCAP FEIA system (Phadia) revealed an increase in specific IgE (kU A /L) to S tuberosum (23.60, >100, and 63.90 at 2, 3, and 4 years of age, respectively); specific IgE to latex was below 0.35 kU A /L. The ImmunoCAP ISAC Microarray Panel summary of positive IgE results (ISU) was as follows: Gal d 1, 2.7; Gal d 2, 1.4; Act d 1, 1.0.After the initial in vivo skin tests and in vitro tests, an oral food challenge was proposed, although it was not performed before the age of 5 years owing to parental refusal. The oral challenge with cooked potato was negative, thus enabling reintroduction of cooked potato in the child's regular diet.With a serum sample from our patient and raw potato extract, 2-dimensional immunoblotting and MALDI-TOF/TOF mass spectrometry analysis made it possible to identify and characterize an IgE-reactive protein that exhibited sequence homology with putative Kunitz-type proteinase inhibitor of S tuberosum (molecular weight of 20.491 kDa and isoelectric point of 5.17) ( Figure) [4].Only 4 potato allergens have been characterized, namely, patatin (Sol t 1) and 3 water-soluble...