Acute Fibrinoid Organizing Pneumonia (AFOP): An Aggressive Organizing Pneumonia (OP) or a Benign Form of Diffuse Alveolar Damage (DAD)?

October 2015, Vol 148, No. 4_MeetingAbstracts

Diffuse Lung Disease | October 2015

Acute Fibrinoid Organizing Pneumonia (AFOP): An Aggressive Organizing Pneumonia (OP) or a Benign Form of Diffuse Alveolar Damage (DAD)? Ana Zamora, MD; Sumedh Hoskote, MBBS; Teng Moua, MD; Joanne Yi; Robert Vassallo, MD Mayo Clinic, Department of Pulmonary and Critical Care Medicine, Rochester, MN Chest. 2015;148(4_MeetingAbstracts):415A. doi:10.1378/chest.2271288

Abstract SESSION TITLE: Non-IPF Diffuse Lung Disease SESSION TYPE: Original Investigation Slide PRESENTED ON: Wednesday, October 28, 2015 at 08:45 AM - 10:00 AM PURPOSE: AFOP represents a distinctive histopathologic pattern associated with a clinical picture of acute lung injury that does not meet criteria for DAD, OP or eosinophilic pneumonia. This pattern has been associated with infections, collagen vascular diseases (CVD), acute exacerbations of interstitial lung diseases (ILD), drug reactions and malignancy.It is characterized by patchy intra-alveolar organizing fibrin deposition (fibrinous balls) and absence of hyaline membranes (which is the hallmark of DAD). We aimed to review our experience to describe clinical course of AFOP. METHODS: We reviewed the medical records of subjects with biopsy proven AFOP from January 2014 to February 2015. Age, gender, clinical presentation, pulmonary function test results, HRCT findings, associated underlying conditions, treatment and outcome were recorded. RESULTS: Twelve subjects (7F/5M) were identified (average age was 48 years). Admitting diagnoses were: acute respiratory failure in 7(58%), pneumonia in 4(33%) and chest pain in 1(9%). One patient required mechanical ventilation. The most common CT finding was diffuse bilateral alveolar infiltrates n=8 (67%). Interstitial opacities were the predominant finding in 4 (33%). Associated histologic findings included non-necrotizing granulomas (n=1), DAD (n=4), and eosinophilic infiltrate (n=2). Of the 4 cases with DAD, 3 had acute exacerbation of ILD and 1 had graft versus host reaction after stem cell transplant for acute myeloid leukemia treatment. Associated underlying conditions included infections (n = 4, 33%), ILD (n =4, 33%), malignancy (n=2, 17%) and the rest were idiopathic (n=2, 17%). For the four ILD cases, 3 had an acute exacerbation secondary to CVD while one was felt to represent a drug reaction to cyclophosphamide. Cases where infection was excluded were treated with steroids. All of the patients in this limited cohort had good response to treatment with no immediate mortality. CONCLUSIONS: Two different clinical courses have been described for AFOP: a fulminant presentation often overlapping with ARDS-DAD and a sub-acute with favorable treatment response. Mortality is been reported more than 30% if mechanical ventilation is required.In our cohort we found ILD and infections as the most common associated conditions to develop AFOP. All of the subjects responded to treatment.

CLINICAL IMPLICATIONS: Clinicians should be aware of this entity when facing acute respiratory failure with bilateral lung infiltrates unresponsive to antibiotic therapy. DISCLOSURE: The following authors have nothing to disclose: Ana Zamora, Sumedh Hoskote, Teng Moua, Joanne Yi, Robert Vassallo No Product/Research Disclosure Information