Acute fibrinous and organising pneumonia: a case report and review of the literature

Abstract

Introduction: Organising pneumonia is a distinct histopathological entity characterized by intra-alveolar buds of granulation tissue, called Masson bodies, which mainly comprise of activated fibroblasts and loose connective tissue. This histopathologic pattern has been described in idiopathic cases, characterizing cryptogenic organising pneumonia as well as in the context of pulmonary infection, drug-induced pneumonitis and following lung transplantation. Although distinct as a clinical and pathological entity, community organising pneumonia may present with atypical clinical and pathological features, such as intra-alveolar fillings of fibrin balls and organising tissue that resembles acute respiratory distress syndrome or diffuse alveolar damage. The latter characteristics constitute a recently described anatomoclinical entity called acute fibrinous and organising pneumonia.

Case presentation: Here, we describe a rare case of acute fibrinous and organising pneumonia, in an otherwise healthy 65-year-old Greek woman who complained of dry cough, fever, weight loss and progressive dyspnoea. She had never been a smoker. Her clinical symptoms showed a rapid deterioration in the two weeks before admission, despite a course of oral antibiotics. After excluding infection and malignancy with routine laboratory tests and flexible bronchoscopy, high resolution computed tomography and video assisted thoracoscopic lung biopsy were performed. Diagnosis was based on radiological features typical of community organising pneumonia coupled with pathologic features characteristic of acute fibrinous and organising pneumonia. The patient was treated with corticosteroids and showed excellent clinical and radiological response three months after treatment initiation.

Conclusion: Acute fibrinous and organising pneumonia is an extremely rare pathologic entity, often misdiagnosed as typical community organising pneumonia. To our knowledge, this is the seventh case of acute fibrinous and organising pneumonia in the literature, with no identifiable cause or association in a female patient, with no underlying lung disease or known exposures and with an unremarkable previous medical history. We highlight the need for careful review of lung biopsies from patients with clinical and radiologic characteristics typical of community organising pneumonia. Although it remains uncertain whether fibrin alters the favourable prognosis and treatment response of community organising pneumonia, it becomes obvious that a thorough pathologic review, apart from establishing the diagnosis of acute fibrinous and organising pneumonia, may predict a more unfavorable outcome therefore alerting the clinician to administer more aggressive and prolonged therapeutic regimens.

Figure 1

Posteroanterior chest radiograph at presentation shows patchy areas of consolidation with a predominantly peripheral and subpleural distribution mainly in the right lung.

Figure 2

High-resolution computed tomography (HRCT) at presentation at the level of the lower pulmonary veins (A) and lower lobes (B) at lung windowing shows a ring-like opacity (arrowhead) and subpleural band-like opacity (arrow) with ground-glass in the centre of them consistent with the "reversed halo sign".

Figure 3

Histological picture of video-assisted thoracoscopic surgery lung biopsy sample. Haematoxylin and eosin stain. The specimens from the right lower and middle lung lobes show preservation of the lung architecture with patchy distribution of intra-alveolar fibrin, in the form of fibrin "balls" (insert a), associated with organizing pneumonia, consisting of intraluminal loose connective tissue within the alveolar ducts and bronchioles (insert b). Hyaline membranes, vascular thrombi or eosinophils are absent. The intervening lung parenchyma between the affected areas shows minimal changes, such as a sparse inflammatory infiltrate or minimal interstitial thickening.

Figure 4

High-resolution computed tomography (HRCT) two months after discontinuation of treatment at the level of the aortic arch (A) and the carina (B) at lung windowing shows deterioration of the disease with extensive subpleural and peribronchovascular consolidation in the right upper lobe (arrows) and with new ring-like opacities consistent with the "reversed halo sign" (arrowhead).

Figure 5

High-resolution computed tomography (HRCT) after three months of continuous corticosteroid therapy at the level of the carina (A) and lower lobes (B) at lung windowing shows significant improvement with almost complete resolution of most of the previously seen consolidations. However new small "migratory" subpleural and peribronchovascular opacities are seen in the left lower lobe (arrow) in a previously uninvolved area.