Abstract Introduction Drug-induced pneumonitis is an important mimic of disseminated infection in immunocompromised hosts. Lenalidomide, an immunomodulatory agent widely used in multiple myeloma, has been associated with organizing and eosinophilic pneumonitis, and occasionally sarcoid-like granulomatous inflammation. The coexistence of acute fibrinous injury and granulomatous inflammation is exceptionally rare. We present a case of lenalidomide-associated acute fibrinous and granulomatous pneumonitis presenting with a miliary pattern following autologous stem cell transplant. Case Presentation A 44-year-old woman with kappa light-chain multiple myeloma, chronic kidney disease stage V, presented with 10 days of fever (to 105 °F), dry cough, hemoptysis, dyspnea and hypoxia requiring high flow oxygen. She had been on maintenance therapy with lenalidomide, daratumumab, and weekly dexamethasone after undergoing an autologous stem cell transplant for multiple myeloma, last administered one week before symptom onset.. CT chest (Figure 1-1) showed innumerable randomly distributed micronodules with ground-glass opacities and septal thickening, suggesting disseminated infection. Laboratory results revealed eosinophilia (950/µL), neutropenia, and profound hypogammaglobulinemia. Empiric piperacillin-tazobactam, doxycycline, and fluconazole were started for possible bacterial and/or fungal infection (history of positive Coccidioides IgM). Two bronchoscopies demonstrated multifocal hypervascular airway lesions. BAL differential showed 15 % eosinophils and 30 % lymphocytes; cultures, Fungitell, and comprehensive testing for bacterial, fungal, mycobacterial, viral, and parasitic pathogens were negative. Cryobiopsy revealed acute fibrinous and granulomatous pneumonitis with negative GMS and acid-fast stains. Following withdrawal of lenalidomide and daratumumab, the patient’s symptoms and CT findings improved without further antimicrobial therapy within the same hospitalization (Figure 1-2). She received an 8-week prednisone taper with inhaled pentamidine prophylaxis. Follow-up CT showed complete clinical and radiographic resolution (Figure 1-3), confirming a grade 3 drug-induced pneumonitis. A bronchoscopy will be repeated to assess the endobronchial vascular lesions. Discussion Lenalidomide related lung injury typically manifests as organizing or eosinophilic pneumonitis. The presence of both fibrinous and granulomatous inflammation suggests a mixed hypersensitivity and immune-complex reaction possibly potentiated by immune reconstitution after autologous transplant. The miliary pattern and BAL eosinophilia closely mimic disseminated fungal or mycobacterial infection. A Naranjo Adverse Drug Reaction Probability Scale score of 7 supported a highly probable causal relationship. Awareness of this pattern is essential, as prompt drug cessation and corticosteroid therapy are curative and prevent progression to fibrotic lung injury. This abstract is funded by: None
Khattar et al. (Fri,) studied this question.