INTRODUCTION: Acute fibrinous and organizing pneumonia (AFOP) is a histologically distinct form of lung injury first described in 2002. Less than 20 cases have been reported since Beasley’s original description and case series. We report a case of idiopathic AFOP and review the literature on this poorly understood entity.
CASE PRESENTATION: A 55 year-old woman active smoker with well-controlled asthma presented with a complaint of progressive dyspnea for one week. On physical exam, she was afebrile with a respiratory rate of 20, oxygen saturation of 85% on ambient air and bilateral, diffuse crackles on chest auscultation. White blood cell count (WBC) was 6.2 K/mm3, and her chemistry and liver function panels were unremarkable. Chest radiograph and computed tomography of the chest were notable for bilateral patchy air-space opacification in the middle and lower lung fields. Despite antibiotic therapy, her respiratory status worsened over the next 24 hours and she required increased oxygen supplementation and ICU care. Bronchoscopy with bronchoalveolar lavage yielded negative cultures and a cell count of: WBC 565, 3% lymphocytes, 6% histiocytes, 26% macrophages, 63% granulocytes with 2% eosinophils. The patient was started on prednisone and slowly improved. An open lung biopsy was performed as radiographic findings persisted.Histology revealed: Presence of multiple intra-alveolar fibrin plugs. Organizing fibrinous pneumonia and acute fibrinous pleuritis. Background lung shows respiratory bronchiolitis.
DISCUSSIONS: In 2002, Beasley described AFOP, a form of acute lung injury with a histologic pattern that differed from diffuse alveolar damage (DAD), organizing pneumonia (OP) and eosinophilic pneumonia (EP). The dominant histological finding of AFOP is the presence of intra-alveolar fibrin (fibrin "balls") and patchy organizing pneumonia. The hyaline membranes that are identified in DAD are not observed. Fibroblastic Masson bodies within the alveolar spaces, ducts and bronchioles are present but not abundant, and eosinophils are rare. Among the 17 cases that comprised Beasley’s initial report of AFOP, the most common symptoms reported were dyspnea, fever, and cough. The most common radiographic finding was bilateral basilar infiltrates. Therapy included antibiotics and steroids. Nine cases were fulminant and died of the disease; eight were subacute. Since Beasley’s initial description, 12 individual case reports of AFOP have been published. All patients had symptoms for less than 2 months, with cough and dyspnea as the most common. Radiographic abnormalities were basal/lower lobe predominant in 6 patients and bilateral in 8 patients. Identified exposures or associated conditions included medications (abacavir and decitabine), hematopoietic stem cell transplant (HSCT), acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) and juvenile dermatomyositis (JDM). In 6 cases, an attributable cause or association could not be identified. Patients were treated with medications including corticosteroids, mycophenolate mofetil, cyclophosphamide, and cyclosporine. Among the 12 case reports, two patients required mechanical ventilation, and two patients died. In addition to these individual case reports, a published description of autopsy findings in 20 patients with SARS reported that 6 of the 20 patients had AFOP on histology. An additional 6 patients had a combination of AFOP and DAD, while the remainder had DAD. Clinical and radiographic details were not reported.
CONCLUSION: AFOP represents a histologically distinct subset of lung injury. Our case represents the 7th case of idiopathic AFOP reported since Beasley’s initial description. Common findings in patients with AFOP are: dyspnea and cough acutely/subacutely, bilateral and basilar predominant radiographic abnormalities. AFOP can result from a variety of insults or be idiopathic. Its varied response to anti-inflammatory therapy suggests that it has a better prognosis than DAD. AFOP may be a part of a spectrum of lung injury that both clinically and histological lies between COP/BOOP and DAD.
DISCLOSURE: Rokhsara Rafii, No Financial Disclosure Information; No Product/Research Disclosure Information