Lung abscess as an adverse effect of Risankizumab

Background Risankizumab is used for prolongated duration by patients, necessitating further research to characterize the infectious risks involved. Case presentation A 30-year-old man on Risankizumab for psoriasis and alopecia presented with pleuritic chest pain, cough, hemoptysis, fever, and myalgias. Initial computed tomography (CT) scan showed a 4.9 × 7.7 × 6.1 cm irregular cavitary lesion in the medial right lower lobe with thickened walls and surrounding ground-glass opacification. Tuberculosis was ruled out with 3 negative acid-fast bacilli (AFB) samples and 2 negative samples for Mycobacterium tuberculosis and rifampin resistance assay (Xpert MTB/RIF). Empiric antibiotic therapy was initiated, though the patient remained persistently febrile and tachycardic despite reported symptomatic improvement. A repeat CT scan showed compression atelectasis of the right middle and lower lobes, and a large right pleural effusion with multiple air-fluid levels. The patient underwent a video-assisted thoracoscopic surgery (VATS) decortication. Pleural fluid culture grew methicillin-resistant Staphylococcus aureus , and sputum AFB culture from admission grew Mycobacterium avium three weeks after collection. The patient ultimately completed two weeks of oral doxycycline. Conclusion Given the lack of notable risk factors for lung abscess, this case suggests a possible association with Risankizumab, which may have contributed to immunosuppression.