LAUSR

TOPIC: Diffuse Lung Disease TYPE: Fellow Case Reports INTRODUCTION: Immune reconstitution inflammatory syndrome (IRIS) has a wide variety of presentations including lung involvement with respiratory failure [1]. While traditionally invoked in AIDS, IRIS is also reported after rituximab therapy [2]. We present a case of inflammatory pneumonia 3 months after receiving Rituximab. CASE PRESENTATION: A 22-year-old woman with Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infection (PANDAS), hypothyroidism, and celiac disease presented with generalized weakness, myalgias, and worsening shortness of breath over a month. She was on Rituximab for 3 years with the last infusion 3 months ago. Interestingly, she reported COVID-19 a month earlier with minimal symptoms, requiring no therapy. She was febrile, tachycardic, and tachypneic requiring supplemental oxygen. Chest CT revealed right upper lobe (RUL) consolidation and patchy consolidative and ground-glass opacities in the left upper and lower lobes.Suspecting community acquired pneumonia, ceftriaxone and azithromycin were started. A COVID-19 and respiratory viral panel PCR were negative. Fever persisted and hypoxemia worsened. Therefore, bronchoscopy was performed. The next day, oxygen requirements increased, and she was moved to ICU on high-flow nasal cannula with 60L FiO2 1.0. Repeat CXR showed subtotal left chest opacification with no pleural effusion on ultrasound. Echocardiography showed preserved LV function. Bronchoscopy cultures were negative. With no response to antibiotics and rapidly worsening CXR changes, Solu-Medrol 125 mg IV q6h was added. Within 24 hours she was improving, being weaned off O2 in 6 days. RUL transbronchial biopsies showed benign alveolar lung parenchyma with some intra-alveolar fibrin deposition with a pool of histiocytic proliferation consistent with organization and with no definitive viral cytopathic effect, vasculitis, or diffuse alveolar damage. All cultures remained negative. CXR changes markedly resolved within 6 days. She was discharged with a slow taper of prednisone. DISCUSSION: This case illustrates a possible exaggerated immune response to tapering levels of immunosuppressive medications such as Rituximab. Her workup ruled out infection and while she also had no active COVID-19, it is conceivable that her recent COVID-19 infection may have activated an exaggerated inflammatory response as the immunosuppression related to Rituximab was subsiding. The rapidly progressing consolidating changes under these circumstances should prompt the clinician to consider IRIS like reactions and rapid institution of steroids seems key to treatment. Whether her PANDAS may have further impacted her immune system making her more prone to this IRIS like response is another consideration that deserves further study. CONCLUSIONS: IRIS is a rare differential diagnosis in rapidly progressing pneumonia that is not just ubiquitous to AIDS patients. REFERENCE #1: J. Mertens, Y. Laghrib, and C. Kenyon, "A Case of Steroid-Responsive, COVID-19 Immune Reconstitution Inflammatory Syndrome Following the Use of Granulocyte Colony-Stimulating Factor," Open Forum Infectious Diseases, vol. 7, no. ofaa326, Aug. 2020, doi: 10.1093/ofid/ofaa326. REFERENCE #2: A. Rao et al., "Safety, efficacy, and immune reconstitution after rituximab therapy in pediatric patients with chronic or refractory hematologic autoimmune cytopenias," Pediatric blood & cancer, vol. 50, no. 4, pp. 822–825, 2008. DISCLOSURES: No relevant relationships by Badri Giri, source=Web Response No relevant relationships by Ahmed Mahgoub, source=Web Response No relevant relationships by seyed pourshahid, source=Web Response No relevant relationships by Seyedmohammad Pourshahid, source=Web Response No relevant relationships by Edmundo Rubio, source=Web Response