# A Case of Primary Gastric Carcinosarcoma with Small Intestine Metastasis

## TL;DR

A rare case of stomach cancer spreading to the small intestine is reported, highlighting the need for clinicians to consider this unusual metastasis pattern.

## Contribution

This paper presents a rare clinical case of primary gastric carcinosarcoma with small intestinal intraluminal metastasis.

## Key findings

- The patient had a gastric carcinosarcoma that metastasized intraluminally to the small intestine.
- The metastatic lesion in the small intestine had identical pathological features to the primary tumor.
- Chemotherapy led to tumor reduction despite metastasis to the lungs.

## Abstract

Primary gastric carcinosarcoma is extremely rare. Herein, we report a case of primary gastric carcinosarcoma with small intestinal intraluminal metastasis.

The patient was a 77-year-old man who was referred to our hospital for further examination of occult fecal blood. At this time, the patient reported lightheadedness, and severe anemia was confirmed, with a hemoglobin level of 6.5 g/dL. Upper gastrointestinal endoscopy revealed a mass with bleeding spots in the middle 3rd of the stomach, which was thought to be the cause of the anemia. The patient’s overall condition was poor; therefore, we decided to limit the surgery to local resection of the primary lesion as palliative treatment, with the main goal of controlling bleeding. The final pathological diagnosis was gastric carcinosarcoma. Postoperatively, the progression of anemia stopped, the patient was able to eat without any problems, and he was discharged home. However, 9 days later, the patient visited the emergency department complaining of abdominal pain. He was diagnosed with intestinal obstruction and underwent surgery. During surgery, a hard mass was palpable in the small intestine, and the lesion was resected. The pathological findings of the small intestinal mass were identical to those of the gastric tumor, and the patient was diagnosed with small intestinal intraluminal metastasis of the gastric carcinosarcoma. Eight months after surgery, pulmonary metastasis was detected by a CT scan. Chemotherapy with capecitabine and irinotecan was initiated, and tumor reduction was achieved.

Primary gastric carcinosarcoma may present with intraluminal metastasis of the small intestine, and clinicians should make a note of this when treating such patients.