P5121 - An Unusual Case of Malignant Gastric Ulcer

Gastric metastasis from pulmonary malignancy (GMPM) is a rare entity (incidence < 2%). The most common sites of GMPM are the small intestine (59.6%) and colorectum (25.6%). The most reliable diagnostic tools are histology and immunohistochemical staining for thyroid transcription factor-1 (TTF-1), Napsin A (Nap-A), and cytokeratin (CK). GMPM research is critical as complications commonly arise as tumor progression continues, including but not limited to perforation and life-threatening gastrointestinal hemorrhage. The purpose of this report is to shed light on this rare presentation as it is often overlooked due to concomitant medical issues.

The patient is a 76-year-old male smoker with a 120 pack years history. Preoperative CT scan for surgical hernia repair incidentally revealed a primary adenocarcinoma of the right lung. Subsequent PET scan revealed a large cavitary mass in the right upper lobe with invasion of the overlying chest wall, small lytic osseous metastasis, and multiple hypermetabolic pulmonary nodules. About 8 months later, after initiating chemotherapy, the patient presented to the hospital with hematuria, dysuria, dark soft stools and bilateral rib pain. Labs at this time revealed a hemoglobin of 6.6; this combined with dark stools raised concern for upper gastrointestinal hemorrhage. EGD revealed a 2 cm clean-based ulcer with heaped up edges in the fundus suggesting neoplasia. Biopsies of the ulcer base were evaluated with histology and immunohistochemical staining. Pathology report revealed +CK7, +TTF1, and +Napsin, confirming adenocarcinoma of pulmonary origin in the gastric fundic ulcer.

Previous studies revealed a majority of GMPM cases occur in elderly men and disseminate hematogenously. Accordingly, the most common site of GMPM is the small intestine due to its robust blood supply. Unfortunately, many GMPM cases present at the end- stage of lung cancer leading to misdiagnosis and missed diagnosis. GMPM is primarily discovered on clinical grounds, as is the case in this patient. Other reports suspected that rising intraluminal pressure due to the malignancy resulted in bowel ischemia and eventual perforation. However, in this case, the metastatic lesion is in the gastric fundus and the lesion’s smaller size did not compromise blood flow to the stomach. GMPM may present with vague signs, including gastrointestinal hemorrhage, perforation, or obstruction, that cannot otherwise be explained by a primary pulmonary malignancy.