Introduction:
Protein contact dermatitis (PCD) is an IgE-dependent allergic reaction which, despite enormous progress in knowledge, remains a ‘non-diagnosed’ nosologic unit in contemporary medicine. Skin lesion, with a chronic and recurring course, are analogous with the clinical picture in allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD); skin patch tests, however, are usually negative. This makes the diagnostics difficult, prevents a correct diagnosis and treatment based on the avoidance of allergen.

Case description:
A 48-year-old woman presented with erythemato-squamous skin lesions, accompanied by a strong itching, occurring on hands for about 6 months. The patient attributed the occurrence of skin lesions to household chores, above all – cooking and contact with food. The contact allergy was not confirmed. Positive results of the prick-by-prick test were observed for potato. Based on the above results, contact eczema induced by potato protein was diagnosed. Allergen elimination and use of emolients were prescribed. A complete remission of skin lesions was obtained.

Discussion:
PCD is rarely diagnosed, which is why there is no substantial epidemiologic data. It is estimated that about 50% of cases are related to atopy. This occurs more often in patients with a damaged dermal-epidermal barrier. Most often, the same products eaten by subjects do not produce any effects. A correct assessment of the substance provoking the occurrence of skin lesions is very important, as most often the products concerned are those commonly used in the household. A detailed PCD diagnostics is very important for obtaining the optimal treatment results.