Case of Gastric Signet Ring Cell Carcinoma With Pulmonary Lymphangitic Carcinomatosis as the Initial Manifestation Diagnosed by Computed Tomography‐Guided Percutaneous Lung Biopsy

Pulmonary lymphangitic carcinomatosis is an interstitial lesion characterised by diffuse growth of metastatic cancer cells within lymphatic vessels. It has an extremely poor prognosis, is clinically difficult to diagnose, and is easily confused with other diseases, including interstitial pneumonia. There are few reports of definite diagnoses confirmed by pathological examinations. A 56‐year‐old woman was admitted to our hospital. The chief complaints were chest tightness, shortness of breath and cough for 2 weeks. HRCT of the lungs showed diffuse thickening of the interlobular septa. Computed tomography‐guided percutaneous lung biopsy targeting the diffuse thickening of the interlobular septa in the lungs revealed adenocarcinoma of gastrointestinal origin. Further gastroscopy revealed an ulcer on the lesser curvature of the stomach; pathological examination confirmed signet ring cell carcinoma. The final diagnosis was secondary pulmonary lymphangitic carcinomatosis caused by gastric signet ring cell carcinoma with respiratory symptoms as the initial manifestation.