Teaching Case

A 44 year old woman presented to our hospital with dry cough of 3 months duration and mild shortness of breath. She had been under treatment with antibiotics with no recession of symptoms.

A 44 year old woman presented to our hospital with dry cough of 3 months duration and mild shortness of breath. She had been under treatment with antibiotics with no recession of symptoms. Personal history was unremarkable. Blood laboratory tests and serologic exams were within normal limits. Pulmonary function tests revealed a restrictive ventilatory defect. The cell count of the bronchoalveolar lavage showed 55% macrophages, 39% lymphocytes, 39% neutrophiles, many foamy macrophages and large activated lymphocytes, findings indicative of hypersensitivity pneumonia or cryptogenic organizing pneumonia (COP). Chest radiograph revealed bilateral multifocal patchy consolidations and nodular opacities. CT imaging confirmed the presence of scattered bilateral peribronchial consolidations with air bronchogram and nodular opacities. Enlarged upper pre-tracheal and pre-vascular lymph nodes were also noted. The findings were suggestive of COP and the patient initiated a treatment with corticosteroids. Follow up chest CT was performed one month later and demonstrated a remarkable recession of lesions and residual ground glass opacities in the place of the initial lesions. Fibrous bands were also visible in the apical-posterior segment of the left upper lobe. The enlarged mediastinal lymph nodes previously observed, were now absent.

Cryptogenic organizing pneumonia (COP) also known as bronchiolitis obliterans organizing pneumonia (BOOP) belongs to the group of idiopathic interstitial pneumonias (IIPs). COP is characterized by the presence of granulation tissue polyps in the alveolar ducts and alveoli that often are occluded and various degree of infiltration of surrounding parenchyma with foamy macrophages and large mononuclear cells.
The consolidations in COP do not represent an active pneumonia but a way of response through a process of granulation tissue proliferation, deposition of fibrin and fibroblast colonization within the distal pulmonary airspaces.
The causative factors of organizing pneumonia include infection, drugs, transplantation, inhalation of toxic gas and collagen-vascular diseases. Exclusion of the above leads to the diagnosis of COP therefore the term “cryptogenic” should be used only in idiopathic cases. COP manifests mainly with patchy peripheral or peribronchovascular consolidations with basal predominance and preservation of lung architecture. Air bronchograms and mild cylindrical bronchial dilatation are common findings. The lesions have various extensions (from focal to whole lobe) and may show migratory nature. Less common findings include irregular linear opacities, solitary focal lesions and multiple nodules that may cavitate. There is no association with cigarette smoking. Men and women are equally affected and the mean age of patients is around 55 years. The onset of symptoms is generally subacute with flu-like symptoms, non productive cough, low grade fever and dyspnoea. Usually they develop over a few weeks. Lung function tests commonly show a mild or moderate restrictive ventilatory defect. The majority of patients recover completely after administration of corticosteroids but relapses occur frequently within 3 months after the end of therapy. The definitive diagnosis should be made after the exclusion of all the other possible causes of organizing pneumonia.