Copyright © 2023 by Author/s and Licensed by Modestum. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Electronic Journal of General Medicine 2023, 20(3), em474 e-ISSN: 2516-3507 https://www.ejgm.co.uk/ Case Report OPEN ACCESS Primary immunodeficiency disease in children: A significant but rare cause of failure to thrive Noorfaizahtul Hanim Md Nawawi 1,2 , Azidah Abdul Kadir 1,2 * , Zainab Mat Yudin 1,2 1 Department of Family Medicine, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, MALAYSIA 2 Hospital Universiti Sains Malaysia, Jalan Raja Perempuan Zainab II, Kubang Kerian, Kelantan, MALAYSIA *Corresponding Author: azidahkb@usm.my Citation: Md Nawawi NH, Abdul Kadir A, Mat Yudin Z. Primary immunodeficiency disease in children: A significant but rare cause of failure to thrive. Electron J Gen Med. 2023;20(3):em474. https://doi.org/10.29333/ejgm/13001 ARTICLE INFO ABSTRACT Received: 17 Jan. 2023 Accepted: 19 Feb. 2023 This case illustrates the rare cause of failure to thrive (FTT) that initially presented with recurrent ear discharge. A five-year-old boy with a history of recurrent ear infections for the past year was treated for acute symptoms during each visit. He later was diagnosed with acute mastoiditis secondary to otitis media by a private otorhinolaryngologist and was referred to a tertiary hospital for admission and parenteral antibiotic commencement. The anthropometric evaluation noted he fell under the group of FTT and had an incidental finding of lower tract respiratory infection that turned out to be tuberculosis infection. Multiple complications occurred during his admission, including candidemia, disseminated tuberculosis, and deep-seated collections. Hence, he was worked up for primary immunodeficiency and was given extensive supportive treatment. Keywords: primary immunodeficiency, failure to thrive, tuberculosis, recurrent otitis media INTRODUCTION Primary immunodeficiency (PID) is a heterogeneous group of inherited diseases characterized by an inborn error in the immunity system. There are more than 400 types of PIDs. It can be further divided into three categories: defects in humoral/antibody production, cellular/immunity defect, or a combination of both. In Malaysia, PID is still under-reported. The prevalence rate of PID reported in Malaysia was 0.37 per 100,000 population [1]. The common forms of PID in Malaysia, as classified by the International Union of Immunological Societies from 1979 until 2020, were among patients with defects in cellular and humoral immunity, followed by antibody deficiencies, congenital phagocyte function defect, dysregulation of immunity, and the least form reported in Malaysia was autoinflammatory disorder [1, 2]. CASE REPORT A five-year-old boy presented with recurrent history of greenish, non-foul smelly ear discharge for the past nine months along with fever. He had four episodes of similar symptoms before this, which were resolved with antibiotics and anti-pyrexia. However, he developed sudden onset of earache and was diagnosed with acute mastoiditis secondary to chronic suppurative otitis media by a private otorhinolaryngologist. He was referred to a local tertiary hospital for initiation of parenteral antibiotics. Upon further questioning, he also had a chronic chesty cough for the past three months and poor weight gain for the past year. The anthropometric assessment noted his weight and height were below 3 rd centile for his age. Ear examination revealed a tender right mastoid area with purulent discharge covering the right tympanic membrane. The left ear canal was erythematous, and the tympanic membrane bulged. Multiple shotty right anterior cervical lymph nodes were felt. Lung examination noted reduced breath sounds over the left middle and lower zone of his lungs. Initial workup revealed his complete blood count noted to have hypochromic microcytic anaemia with thrombocytosis, predominantly neutrophils. His inflammatory markers increased with an erythrocyte sedimental rate level of 90 mm/Hr and C-reactive protein of 190.4 mg/L. His baseline renal and liver functions were normal. However, the chest radiograph noted to have left lower lobe consolidation. sputum sent for acid-fast bacilli smears were negative. Two sputum samples were sent for gene expert and second gene expert sample of his sputum came back with mycobacterium bacilli detected. TB culture eventually support the TB diagnosis. An initial PID workup was sent and revealed a low level of total T cells and a high level of NK cells. He was started on parenteral amoxycillin-clavulanic acid and anti-tuberculosis. Unfortunately, he was noted to have persistent spikes of temperature during this admission, which was attributed to retropharyngeal abscess and otomastoiditis as evidenced by CT imaging. Hence, he was subjected to surgical aspiration and histology taken from the abscess wall confirmed features of caseating chronic granulomatous inflammation. His temperature, however failed to be settled.