INTRODUCTION: Bronchoalveolar carcinoma (BAC) is a subtype of adenocarcinoma developing from terminal bronchiolar and acinar epithelia. Growth is progressive in a lepidic and/or aerogenous manner with preservation of the underlying lung architecture. BAC can vary in presentation making the diagnosis challenging and often delayed. We present a patient who presented with diffuse variant BAC mistaken for an interstitial lung disease (ILD) and was referred for consideration of lung transplantation.
CASE PRESENTATION: A 67 year old Venezuelan woman, former smoker, presented for lung transplant evaluation in February 2010. In 2006, a routine chest radiograph identified a right lower lobe nonspecific density. After observation, in December 2007 her chest radiograph showed progression of the density. She had further evaluation at a major quaternary cancer center in the United States in January 2008 and her computed tomography (CT) reported evidence of an irregular right lower lobe cavitary lesion with bronchiectatic changes. Bronchoscopy was performed with bronchoalveolar lavage and bronchial washings failed to establish a diagnosis. No specific therapy was provided and further observation was recommended. While traveling to London in April 2009 she developed symptoms of an upper respiratory tract infection which progressed to pneumonia. Evaluation included another bronchoscopy which was non-diagnostic. It was felt she had ILD based on findings of bilateral peripheral consolidations. In May 2009 she was also evaluated in Spain with another bronchoscopy and imaging with similar findings and conclusions. She was treated with additional antibiotics. Azathioprine was initiated along with high dose corticosteroids. Despite this her dyspnea and hypoxemia continued to deteriorate. By February 2010 she was referred to our center to explore the possibility of lung transplantation for her unclassified ILD. Her physical exam was remarkable for appearing dyspneic and audible bilateral crackles. Her oximetry was 86% on room air. Pulmonary function testing revealed severe restriction. Chest radiograph showed dense airspace opacity throughout both lungs. The CT thorax revealed widespread peripheral alveolar consolidation and honeycombing with scattered tree-in-bud nodularity and groundglass opacities. Given the atypical nature of her presumed ILD we performed yet another bronchoscopy. Findings revealed abundant thin secretions without any clear endobronchial lesions. Transbronchial lung biopsies were performed revealing a classic histological pattern consistent with mucinous BAC. Currently she is receiving treatment with erlotinib at her home in Venezuela.
DISCUSSIONS: BAC can present as a solitary peripheral lung nodule, multiple pulmonary nodules, or lobar consolidation. Particularly, radiographic presentation of BAC with lobar consolidation can resemble that of bacterial pneumonia and the diagnosis may not be considered until the clinical symptoms and radiographic abnormalities fail to respond to treatment. In our case we describe a patient with diffuse progressive infiltrative lung disease with significant hypoxemia. The differential diagnosis of sarcoidosis, chronic eosinophilic pneumonia, cryptogenic organizing pneumonia, atypical infectious process, and the other idiopathic interstitial pneumonias were entertained. Despite atypical features, empiric treatment and even referral for transplantation for her presumed ILD was persued, without a clear histopathologic confirmation of a diagnosis. With the advent of high-resolution CT, there has been a decrease in the pursuit of an open lung or even bronchoscopic lung biopsy in the diagnosis of diffuse parenchymal lung disease, particularly the idiopathic interstitial pneumonias. However, our case illustrates the importance of maintaining a broad differential in the approach to a patient with a diffuse parenchymal lung disease and to always consider histopahtologic diagnosis in atypical presentations.
CONCLUSION: BAC presenting as a diffuse pulmonary process may be mistaken for an ILD, delaying the diagnosis, treatment, and potentially exposing the patient to the toxicity of unnecessary treatment. BAC should be considered in the differential diagnosis of a diffuse parenchymal lung disease, and biopsy confirmation should be considered in atypical presentations.
DISCLOSURE: Vichaya Arunthari, No Financial Disclosure Information; No Product/Research Disclosure Information