Pulmonary pleomorphic carcinoma mimicking small bowel obstruction

SESSION TITLE: Lung Cancer Case Report Posters 2 SESSION TYPE: Case Report Posters PRESENTED ON: 10/09/2023 12:00 pm - 12:45 pm INTRODUCTION: Pulmonary pleomorphic carcinoma (PC) is a rare, aggressive subtype of sarcomatoid carcinoma. It usually presents as a peripheral mass comprised of a mixture of giant and spindle cells. The incidence of PC is between 0.1-0.4% of all lung cancers and tends to metastasize to adjacent structures in the early stage [1]. Here we discuss a case of metastatic PC masquerading as abdominal pain from small bowel obstruction. CASE PRESENTATION: An 87-year-old male with a history of adenocarcinoma, COPD, hypertension, hyperlipidemia, diabetes, smoking and chronic kidney disease presented with abdominal pain for 3 days. He reported symptoms of loose stool, diarrhea, and excessive flatulence in the week prior. CT scan of the abdomen and pelvis revealed small bowel obstruction from a right lower quadrant abdominal mass measuring 7x8 cm (Figure 1). After undergoing an exploratory laparotomy with resection, patient was found to have an undifferentiated malignant tumor with sheets of spindle cells, giant cells, and some small cells with a rhabdoid/signet ring cell appearance. Numerous mitotic figures with areas of tumor necrosis were also noted. The tumor was centered in the mesentery and extended to the muscularis propria. Immunohistochemical staining was positive for keratin AE1/AE3, CK7, TTF-1, and Napsin A. Additional CT imaging of the abdomen/pelvis revealed a 10 cm mass in the gastrohepatic region with an enlarging adrenal mass and a lytic lesion in the sacrum (Figure 2). Overall, the morphology, immunostaining, and patient history supported a diagnosis of a metastatic PC from the lung. DISCUSSION: Tumors of the small intestine are usually metastatic and originate from adjacent organs, such as stomach, pancreas, and colon [2]. Metastatic primary lung cancer to the gastrointestinal tract is rare, occurring in 0.2-1.7% of cases [1]. Initial findings are subtle and isolated, such as a single polyp or an obstruction [2], but abdominal pain is the most common presenting symptom, followed by intestinal perforation, melena, nausea, and vomiting [3]. These symptoms can be attributed to mesenteric masses that infiltrate into the bowel wall [3].There have only been 44 unique case reports of primary lung metastasizing to the colon, of which 45% can be attributed to squamous cell carcinoma, 11% to small cell carcinoma, and 7% to large cell carcinoma [2], Only 2 cases of metastatic PC to the colon, and small bowel were reported [2]. Small bowel obstructions are normally most prevalent in patients with ovarian cancer (5.5-42%), colorectal cancer (4.4-24%), and gastric cancer [2]. As such, our case of metastatic PC causing small bowel obstruction is truly a unique pathology. CONCLUSIONS: Pulmonary PC is an aggressive tumor that rarely metastasizes to the gastrointestinal tract. Because of its atypical cell morphology and poor differentiation, it presents as a diagnostic challenge for clinicians. Despite its rarity, clinicians should consider the possibility of gastrointestinal metastasis when evaluating lung cancer patients exhibiting signs of abdominal pain. REFERENCE #1: Zhang X, Wang Y, Zhao L, Jing H, Sang S, Du J: Pulmonary pleomorphic carcinoma: A case report and review of the literature. Medicine (Baltimore). 2017, 96:e7465. 10.1097/md.0000000000007465 REFERENCE #2: Parker NA, McBride C, Forge J, Lalich D: Bowel obstruction caused by colonic metastasis of lung adenocarcinoma: a case report and literature review. World J Surg Oncol. 2019, 17:63. 10.1186/s12957-019-1611-y REFERENCE #3: Burnette RE, Ballard BR: Metastatic pleomorphic carcinoma of lung presenting as abdominal pain. J Natl Med Assoc. 2004, 96:1657-1660 DISCLOSURES: No relevant relationships by Arjun Bhatt No disclosure on file for Jayanth Keshavamurthy No relevant relationships by Paul Kirkpatrick No relevant relationships by Sameena Salcin No disclosure on file for Varsha Taskar