Small cell carcinoma of the ileum that developed 10 years after total gastrectomy for gastric signet-ring cell carcinoma.

Abstract

To the Editor: Small cell carcinoma (SCC) of the small intestine including the ampulla of Vater is extremely rare; only 3 cases of SCC of the small intestine have been reported. A 65-year-old man underwent total gastrectomy for gastric advanced pure signet-ring cell carcinoma. Ten years later (at the age of 75 y), he presented with abdominal pain. Upper gastrointestinal endoscopy showed elevated tumor at the ileum near the anastomosis junction between esophagus and ileum (Fig. 1A). Biopsies revealed carcinoma cells of very small size (Fig. 1B). They showed hyperchromatic nuclei, very scant cytoplasm, molded nuclei, and inconspicuous nucleoli. The features are those of SCC. No signet-ring carcinoma cells and adenocarcinoma cells were recognized. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) AE1/3 (Fig. 1C), CK CAM5.2, KIT (Fig. 1D), chromogranin (Fig. 1E), synaptophysin, neuron-specific enolase, p53 (Fig. 1F), and Ki-67 (labeling=70%). They were negative for CD68 (NCAM), platelet-derived growth factor receptor a, CDX-2, and thyroid transcription factor-1. Because the neuroendocrine markers (chromogranin, synaptophysin, and neuron-specific enolase) and KIT were positive, the immunohistochemical findings are those of SCC. Because no abnormalities were found in the lungs; and tumor cells were negative for thyroid transcription factor-1, metastatic SCC from the lung was denied. A diagnosis of SCC of the ileum was made. The tumor was inoperative because many lymph node metastases were found in the abdomen by various imaging modalities. Retrospective immunohistochemistry showed that the gastric carcinoma cells were positive for CK AE1/3, CK CAM5.2, p53, and Ki-67 (labeling=30%). They were negative for KIT, chromogranin, synaptophysin, CD56, neuron-specific FIGURE 1. A, Endoscopy shows elevated tumor of the ileum. B, Histology of biopsy. The tumor cells are very small and have hyperchromatic nuclei, inconspicuous nucleoli, scant cytoplasm, molded nuclei, and increased nucleo-cytoplasmic ratio. The features are those of small cell carcinoma (SCC). Hematoxylin and eosin, 200. C, The SCC cells are strongly positive for cytokeratin AE1/3. Immunostaining, 200. D, The SCC cells are positive for KIT. Immunostaining, 200. E, The SCC cells are focally positive for chromogranin. Immunostaining, 200. F, The SCC cells are diffusely positive for p53. Immunostaining, 200.