Malignancy: A Great Masquerader

Abstract

INTRODUCTION: Biopsy is recommended for definitive diagnosis in a majority of cases of suspected interstitial lung disease (ILD) (1), although a trial of treatment often precedes histopathologic examination. We report a case of metastatic cholangiocarcinoma presenting with symptoms, pulmonary function testing, and imaging consistent with ILD. CASE PRESENTATION: A 62-year-old non-smoking male with ulcerative colitis reported a two-month history of dyspnea on exertion and non-productive cough. Chest radiograph was unremarkable. The patient was diagnosed with bronchitis and treated with azithromycin. His symptoms worsened, and, one month later, he presented to our facility. At the time of our evaluation, the patient reported serving most of his life in the military, working in the dental field. He acknowledged exposure to wet gypsum (hydrated calcium sulfate), but denied other toxic exposures. On examination, auscultation of the chest revealed fine inspiratory crackles in the lower half of each posterior hemithorax. No clubbing was noted. Oxyhemoglobin saturation on ambient air decreased from 97% at rest to 89% with ambulation. Pulmonary function testing revealed a decreased FEV1 (72% predicted) and FVC (75% predicted) with a normal FEV1/FVC ratio. Total lung capacity was normal (85% predicted). Diffusing capacity was reduced (52% predicted). Computed tomography demonstrated nodular-appearing septal thickening and scattered peripheral ground glass opacities (Figure 1). Bronchoscopy with bronchoalveolar lavage excluded bacterial, fungal, and mycobacterial disease. Soon thereafter, the patient demonstrated rapidly progressive respiratory symptoms. Urgent video-assisted thorascopic surgery (VATS) wedge biopsy revealed low-grade adenocarcinoma with enteric features present in the pulmonary arteries and lymphatics (Figure 2). Immunohistochemistry staining of the tumor demonstrated loss of SMAD-4 immunoreactivity, a feature of pancreaticobiliary adenocarcinomas. Staging imaging demonstrated rapid progression of pulmonary metastatic disease and a central liver mass associated with intraductal dilatation. DISCUSSION: Extrathoracic malignancies demonstrating lymphatic and hematogenous penetration in the lung may mimic both early inflammatory changes and advanced reticulonodular abnormalities that are characteristic of ILD (3). CONCLUSIONS: Our case underscores the importance of tissue diagnosis in cases of suspected ILD that do not demonstrate a classic radiographic pattern, documented environmental exposure, or identifiable systemic disease responsible for observed roentgenologic abnormalities (2).