Chronic cough of unknown primary.
Molina-Pallete GM, and Ray C. Chronic cough of unknown primary. Am J Respir Crit Care Med 2017; 195.
Am J Respir Crit Care Med
Cough is one of the most common symptoms for which patients seek medical attention. The most common etiologies are asthma, gastroesophageal reflux (GERD) or post nasal drip. Lung cancer is also an etiology in less than 2 percent of cases of chronic cough. Cancer of unknown origin (CUO) is a relatively common clinical entity, accounting for 4 to 5 percent of all invasive cancers. Seventy percent of CUO are Adenocarcinomas. One of the presentations of CUO is lymphangitic carcinomatosis, morphologically defined by the presence of a tumor within pulmonary lymphatics and is usually diagnosed post mortem. Pulmonary lymphangitic carcinomatosis is associated with adenocarcinoma of the stomach, lung, head and neck, and esophagus. Case 65 year old female has been experiencing chronic cough for 5 months after a trip to Florida. Patient has been treated for GERD, postnasal drip and asthma without improvement. Cough is persistent, non-productive, in spells 5 to 6 times a day including nights. No viral infection at onset. She is a house wife, has never smoked and has no pets at home. No weight loss or family history of malignancy. PFTs showed mild obstruction with mild diffusion impairment (FEV1 2.35, FVC 3.49 DLCO 15.1). Chest X ray showed interstitial markings in both bases. High resolution computer tomography (HRCT) showed bilateral septal thickening with patchy small areas of ground glass opacities/nodularity throughout both lungs. After those finding our differential diagnosis was chronic hypersensitivity pneumonitis. Patient underwent bronchoscopy. Pathology was positive for adenocarcinoma of unknown origin with lymphangitic spread. Negative TTF-1, Napsin A, p63, GATA3, and CDX2. Negative ALK and EGFR. Positive for CK7 and P53. PET showed metastasis to vertebra T1, T2 and T4. Normal thyroid, colonoscopy, mammogram, PAP smear and urine cytology. Patient received Cisplatin with Pemetrexed follow by nivolumab. Developed right side pleural effusion with positive cytology for adenocarcinoma. Patient died in hospice Discussion Finding the etiology of chronic cough could be a challenge. This patient completed an initial work up that was negative. Interstitial lung disease was high in our differential however the diagnosis was unexpected. The possible primaries include upper GI tract, ovaries, pancreatic-biliary tract and lung, among others. Tumor board considered her Stage IV lung adenocarcinoma. Evaluation of a common symptom like chronic cough is vital and malignancy should always be part of the differential.