A case of rectal carcinoid

Abstract

A case of carcinoid tumor arising in the rectum of a 60-year-old male was reported with special reference to the cytological features of tumor cells. In a stamp preparation, tumor cells appeared to be in cell clusters or loosely arranged in cell sheets with occasional rosette-like pattern. Small tumor cells with naked nuclei were also observed scatteredly. A majority of tumor cells were characterized by uniform, round nuclei with coarsely granular chromatin and light green-tinct foamy cytoplasms with indistinct cell borders. There were a few small atypical cells with pyknotic nuclei and scant cytoplasms. The nucleoli were not prominent. The tumor was a slightly elevated submucosal tumor measuring 1.6×1.3cm in size. A histologic examination revealed mixed type of carcinoid tumor infiltrating up to the muscle layer with metastasis to one of regional lymph nodes. An electron microscopic study confirmed that the tumor cells contained many secretory granules of high electron density measuring 100 to 300 nm in diameter. In the present case, no elevation of urinary 5 HIAA or plasma serotonin was noted, and carcinoid syndrome was not shown.