Component-resolved diagnosis (CRD) of IgE-mediated hypersensitivities is challenged by the possibility that single patients are sensitized to components not commercially available to the clinical lab. Here, we studied a patient with positive extract-based diagnosis of house dust mite (HDM) allergy based on routine in vivo (prick test) and in vitro (serum specific IgE) tests, whose serum scored negative for IgE to the three recombinant allergens routinely used in CRD (group 1 allergens, group 2 allergens and tropomyosin). By means of serological proteome analysis via two-dimensional gel electrophoresis combined with immunoblotting and mass spectrometry, paramyosin (group 11 allergen: Der f 11 and Der p 11) was identified as the allergen component recognized by serum IgE from this patient in a raw allergen extract. Nine patients (64%) had IgE to Der p 11 in a group of 14 HDM allergic patients. Biological significance Our results add up to previous reports indicating that paramyosin is a clinically relevant HDM allergen and highlight that it can represent, in some patients, the first sensitizing component of this allergen source. This suggests that, at the moment, the use of allergen extract for the purpose of measuring IgE reactivity cannot be replaced by component resolved diagnosis and that group 11 allergens should be included among allergen components routinely tested in the clinical laboratory. © 2017 Elsevier B.V.