SESSION TITLE: Challenging Cases of Hemophagocytic LymphohistiocytosisSESSION TYPE: Rapid Fire Case ReportsPRESENTED ON: 10/19/2022 12:45 pm - 1:45 pmINTRODUCTION: Acute fibrinous and organizing pneumonia (AFOP) is a rare histopathological finding associated with acute or subacute lung injury. It can be idiopathic or secondary to other conditions including hemophagocytic lymphohistiocytosis (HLH). HLH is a life-threatening systemic inflammatory response that may be genetic or due to an underlying cause. We highlight a case of AFOP in the setting of HLH.CASE PRESENTATION: A 26-year-old man with a history of recent infectious mononucleosis presented to the emergency department with fatigue, nausea, fever, and shortness of breath. He was intubated for hypercapnic and hypoxic respiratory failure and admitted to the medical intensive care unit with severe acute respiratory distress syndrome and hepatorenal failure. Labs were notable for WBC 15.82k/mm3 with neutrophil predominance, hemoglobin 11.7g/dL, platelets 29k/mm3, AST 316U/L, ALT 517U/L, Bilirubin 35.1mg/dL, direct bilirubin 29mg/dL. Further workup revealed negative ANCA, ferritin 8,500UG/L, IL-2 receptor 36,430.2pg/nL, triglycerides 394mg/dL, procalcitonin 167.74ng/mL, prothrombin time 24.5 seconds, international normalized ratio 2.10, activated partial thromboplastin time 26.7 seconds fibrinogen 508mg/dL and EBV IgM negative, EBV PCR positive.CT chest, abdomen, and pelvis without contrast revealed bilateral cavitary lung nodules, consolidation with small pleural effusions and hepatosplenomegaly.Bronchoscopy with bronchoalveolar lavage was negative for malignant cells. A thoracentesis performed revealed an exudative effusion with LDH of 1040U/L.Liver biopsy was negative for EBV-encoded small RNA.He underwent right upper lobe wedge resection. Biopsy revealed necrotizing acute inflammation of parenchyma and intra-alveolar fibrin balls with foci of organization. Fungal structures or acid fast bacili are not seen on GMS, PAS, and AFB stains.Bone marrow biopsy showed no evidence of malignancy but rare suspicious hemophagocytes.Since the patient met criteria for HLH, he was initiated on pulse dose steroids and etoposide with improvement in his symptoms. He was extubated and has since come off dialysis, and is completing outpatient therapy. Subsequent CT imaging prior to discharge revealed resolution of ground glass opacities, scarring, stable bilateral cavitary lesions.DISCUSSION: This case highlights a healthy man with EBV induced HLH causing cavitary lesions on CT imaging. Concurrently, these lesions pathologically resembled acute fibrinous and organizing pneumonia. Treatment of his HLH is what ultimately led to clinical and lab improvement with stability of his CT findings.CONCLUSIONS: AFOP has been reported in association with HLH. Radiographically, it can present as diffuse cavitary nodules. Although rare, it is important to consider and investigate AFOP and HLH in the setting of multi-organ failure with recent EBV infection.Reference #1: Wu X, Wang K, Gao Y, Cai Y, Wang W, Zhong D, Zhan Q. Acute fibrinous and organizing pneumonia complicated with hemophagocytic lymphohistiocytosis caused by chronic active Epstein-Barr virus infection: a case report. BMC Infect Dis. 2021 Dec 4;21(1):1207. doi: 10.1186/s12879-021-06868-0. PMID: 34863102; PMCID: PMC8642748.Reference #2: Nishino M, Mathai SK, Schoenfeld D, Digumarthy SR, Kradin RL. Clinicopathologic features associated with relapse in cryptogenic organizing pneumonia. Hum Pathol. 2014 Feb;45(2):342-51. doi: 10.1016/j.humpath.2013.09.010. Epub 2013 Oct 3. PMID: 24342432.Reference #3: Bergsten E, Horne A, Aricó M, Astigarraga I, Egeler RM, Filipovich AH, Ishii E, Janka G, Ladisch S, Lehmberg K, McClain KL, Minkov M, Montgomery S, Nanduri V, Rosso D, Henter JI. Confirmed efficacy of etoposide and dexamethasone in HLH treatment: long-term results of the cooperative HLH-2004 study. Blood. 2017 Dec 21;130(25):2728-2738. doi: 10.1182/blood-2017-06-788349. Epub 2017 Sep 21. PMID: 28935695; PMCID: PMC5785801.DISCLOSURES: No relevant relationships by Tarik Al-BermaniNo relevant relationships by Anant JainNo relevant relationships by Ian KaplanNo relevant relationships by Alina KifayatNo relevant relationships by Lisa Paul SESSION TITLE: Challenging Cases of Hemophagocytic Lymphohistiocytosis SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/19/2022 12:45 pm - 1:45 pm INTRODUCTION: Acute fibrinous and organizing pneumonia (AFOP) is a rare histopathological finding associated with acute or subacute lung injury. It can be idiopathic or secondary to other conditions including hemophagocytic lymphohistiocytosis (HLH). HLH is a life-threatening systemic inflammatory response that may be genetic or due to an underlying cause. We highlight a case of AFOP in the setting of HLH. CASE PRESENTATION: A 26-year-old man with a history of recent infectious mononucleosis presented to the emergency department with fatigue, nausea, fever, and shortness of breath. He was intubated for hypercapnic and hypoxic respiratory failure and admitted to the medical intensive care unit with severe acute respiratory distress syndrome and hepatorenal failure. Labs were notable for WBC 15.82k/mm3 with neutrophil predominance, hemoglobin 11.7g/dL, platelets 29k/mm3, AST 316U/L, ALT 517U/L, Bilirubin 35.1mg/dL, direct bilirubin 29mg/dL. Further workup revealed negative ANCA, ferritin 8,500UG/L, IL-2 receptor 36,430.2pg/nL, triglycerides 394mg/dL, procalcitonin 167.74ng/mL, prothrombin time 24.5 seconds, international normalized ratio 2.10, activated partial thromboplastin time 26.7 seconds fibrinogen 508mg/dL and EBV IgM negative, EBV PCR positive. CT chest, abdomen, and pelvis without contrast revealed bilateral cavitary lung nodules, consolidation with small pleural effusions and hepatosplenomegaly. Bronchoscopy with bronchoalveolar lavage was negative for malignant cells. A thoracentesis performed revealed an exudative effusion with LDH of 1040U/L. Liver biopsy was negative for EBV-encoded small RNA. He underwent right upper lobe wedge resection. Biopsy revealed necrotizing acute inflammation of parenchyma and intra-alveolar fibrin balls with foci of organization. Fungal structures or acid fast bacili are not seen on GMS, PAS, and AFB stains. Bone marrow biopsy showed no evidence of malignancy but rare suspicious hemophagocytes. Since the patient met criteria for HLH, he was initiated on pulse dose steroids and etoposide with improvement in his symptoms. He was extubated and has since come off dialysis, and is completing outpatient therapy. Subsequent CT imaging prior to discharge revealed resolution of ground glass opacities, scarring, stable bilateral cavitary lesions. DISCUSSION: This case highlights a healthy man with EBV induced HLH causing cavitary lesions on CT imaging. Concurrently, these lesions pathologically resembled acute fibrinous and organizing pneumonia. Treatment of his HLH is what ultimately led to clinical and lab improvement with stability of his CT findings. CONCLUSIONS: AFOP has been reported in association with HLH. Radiographically, it can present as diffuse cavitary nodules. Although rare, it is important to consider and investigate AFOP and HLH in the setting of multi-organ failure with recent EBV infection. Reference #1: Wu X, Wang K, Gao Y, Cai Y, Wang W, Zhong D, Zhan Q. Acute fibrinous and organizing pneumonia complicated with hemophagocytic lymphohistiocytosis caused by chronic active Epstein-Barr virus infection: a case report. BMC Infect Dis. 2021 Dec 4;21(1):1207. doi: 10.1186/s12879-021-06868-0. PMID: 34863102; PMCID: PMC8642748. Reference #2: Nishino M, Mathai SK, Schoenfeld D, Digumarthy SR, Kradin RL. Clinicopathologic features associated with relapse in cryptogenic organizing pneumonia. Hum Pathol. 2014 Feb;45(2):342-51. doi: 10.1016/j.humpath.2013.09.010. Epub 2013 Oct 3. PMID: 24342432. Reference #3: Bergsten E, Horne A, Aricó M, Astigarraga I, Egeler RM, Filipovich AH, Ishii E, Janka G, Ladisch S, Lehmberg K, McClain KL, Minkov M, Montgomery S, Nanduri V, Rosso D, Henter JI. Confirmed efficacy of etoposide and dexamethasone in HLH treatment: long-term results of the cooperative HLH-2004 study. Blood. 2017 Dec 21;130(25):2728-2738. doi: 10.1182/blood-2017-06-788349. Epub 2017 Sep 21. PMID: 28935695; PMCID: PMC5785801. DISCLOSURES: No relevant relationships by Tarik Al-Bermani No relevant relationships by Anant Jain No relevant relationships by Ian Kaplan No relevant relationships by Alina Kifayat No relevant relationships by Lisa Paul