S3050 Gastric Mass as a Rare Presentation of Primary Lung Carcinoma

Abstract

INTRODUCTION: Symptomatic gastrointestinal metastases are a rare initial presentation of primary lung cancer. The most common sites of lung cancer metastasis are lymph nodes, liver, adrenal glands, bone, and brain. Gastric metastases are often asymptomatic. We report a case of a gastric mass as the initial clinical manifestation of primary small cell lung cancer (SCLC). CASE DESCRIPTION/METHODS: An 82 year old woman with past medical history of hypertension and asthma presented with a complaint of abdominal pain, abdominal distention, and associated shortness of breath for one month. She also endorsed nausea and weight loss (∼25 lbs). She is a former smoker, quitting 19 years prior. Physical exam was notable for moderate abdominal distention with positive fluid wave. CT abdomen showed large volume ascites and an ill-defined mass of the stomach originating from the lesser curvature and extending into the liver hilum, with extensive peritoneal metastatic implants. Paracentesis revealed red-tinged ascitic fluid, with cytology studies suggestive of metastatic cancer of likely gastric origin. Esophagogastroduodenoscopy (EGD) demonstrated external compression of the stomach along the lesser curvature > 5 cm, and two large gastric ulcers >2 cm each with raised edges along the greater curve. Endoscopic ultrasound (EUS) revealed a mixed echogenic gastric mass along the lesser curvature to the antrum abutting the portal vein ( >8 cm longitudinally, and >5 cm vertically), with an area of necrosis (1 cm × 1.5 cm) within the lesion. No vascular flow was identified within the lesion. Additionally, hypoechoic lesions typical of lymph nodes were seen in the mediastinum, celiac axis, and porta hepatis. Pathology report of the tissue biopsy revealed small cell carcinoma, and immunohistochemistry analysis was positive for CD56, TTF-1, and CAM5.2, suggestive of gastric metastasis from primary small cell lung carcinoma. The patient was started on carboplatin/etoposide chemotherapy. DISCUSSION: Small cell lung carcinoma initially presenting with gastrointestinal symptomatology is a rare occurrence. In our patient, the ascitic fluid cytology and the radiologic finding of a large gastric mass were initially suggestive of a primary gastric carcinoma. However, on further staging efforts with EGD/EUS and gastric tissue biopsy, the true primary lesion was revealed to be of lung origin, demonstrating the importance of gastroscopy and detailed immunohistochemistry studies in establishing an accurate diagnosis.