S2853 Metastatic Lung Adenocarcinoma Presents as Small Bowel Perforation

Abstract

INTRODUCTION: Lung adenocarcinomas are often diagnosed at the advanced stage of disease and gastrointestinal metastases from pulmonary neoplasms are rare with the incidence of 0.2-0.5%. Early diagnosis of small intestinal metastasis is difficult due to the low incidence of symptoms and scarcity of imaging modalities to evaluate small intestinal lumen. Here, we present a case of visceral perforation of the ileum from lung adenocarcinoma metastasis. CASE DESCRIPTION/METHODS: A 61 years old Caucasian male with a history of lung adenocarcinoma and metastatic lymphadenopathy presented with severe acute abdominal pain. A recent PET scan revealed interval improvement of the lung mass with decreasing nodal sizes after chemotherapy with docetaxel and ramucirumab. Vital signs were unremarkable and physical examination revealed a distended abdomen with significant abdominal tenderness, involuntary guarding, and Blumberg sign. Laboratory results noted marked leukocytosis of 30,000 per microliter with 16% band neutrophils. Computerized tomography (CT) of the abdomen and pelvis revealed extraluminal gas and ruptured viscus (Figure 1). Exploratory laparotomy revealed mid ileal perforation and a totally constricted lumen. The patient underwent resection of 30 cm of the mid-ileum with end-to-end anastomosis. Histology (Figure 2) and immunochemistry (Figure 3) findings were similar to the carcinoma in the previous nodal biopsy. The patient was referred to outpatient oncology follow-up with chemotherapy and a short-term follow up in 6 months was uneventful. DISCUSSION: Perforations occurs more commonly in Jejunum (53%) than ileum (28%). Histological type associated with gastrointestinal metastasis is still unclear. Small bowel perforation can occur even with a favorable prognosis as evidenced by our patient’s staging PET/CT scan showing improved tumor burden. Once metastasis occurred to small bowel, they trend to perforate due to tumor necrosis rather than obstruction. Intestinal tumor metastases are uncommon but should be considered in the diagnosis of a patient with an acute abdomen with a history of pulmonary neoplasm. The surgical approach is mandatory even as a palliative measure. Preoperatively establishing, or suspecting, a diagnosis of metastases to the small bowel can help inform surgical planning and ultimately enhance outcomes.Figure 1.: Coronal Imaging of computed tomography (CT) of the abdomen pelvis with contrast revealed extraluminal gas and ruptured viscus (white circle).Figure 2.: Small bowel resection showing poorly differentiated adenocarcinoma (hematoxylin-eosin, original magnification 40X).Figure 3.: Small bowel resection poorly differentiated adenocarcinoma showing positive TTF-1 nuclear expression by immunohistochemistry most consistent with metastatic poorly differentiated adenocarcinoma of lung primary (original magnification 200X).