Pseudomonal sternal abscess and osteomyelitis as an initial manifestation of common variable immunodeficiency

ABSTRACT Background Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency in adults and is characterized by hypogammaglobulinemia and recurrent bacterial infections. The initial presentation of sternal osteomyelitis and abscesses, particularly due to Pseudomonas aeruginosa , is exceedingly rare. Case Summary We report the case of a 39-year-old, previously healthy male who presented with progressive right-sided chest pain and an anterior chest wall mass. Imaging revealed sternal bone erosion with an associated parasternal soft-tissue collection. Surgical exploration revealed two sternal abscess cavities, and cultures grew pan-susceptible Pseudomonas aeruginosa . Laboratory studies revealed profound hypogammaglobulinemia, and flow cytometry revealed a small monoclonal B-cell population. Autoimmune and infectious workup results were unremarkable. The patient underwent serial surgical debridement and received 6 weeks of intravenous cefepime with initiation of intravenous immunoglobulin therapy for the newly diagnosed CVID. At the 3-month follow-up, there was complete clinical resolution with no evidence of recurrent infection. Conclusion This case highlights a rare presentation of CVID with sternal osteomyelitis and abscess caused by Pseudomonas aeruginosa . This underscores the importance of considering primary immunodeficiency in adults with atypical or severe infections and highlights the diagnostic and therapeutic challenges posed by such unusual presentations. Early identification and immunoglobulin replacement therapy are critical for achieving favorable outcomes.