61-year-old male suffered from recurrent flushing, especially in stressful situations. He underwent partial resection of the ileum.
- Transverse section of the wall of the ileum.
- Circumscribed tumor located predominantly in the submucosa that infiltrates into lymphatic vessels.
- The tumor consists of anastomosing strands and nests of cuboidal and polygonal cells which are separated by delicate fibrous septa. Tumor cells exhibit cytoplasmic staining for chromogranin A, a marker specific for neuroendocrine cells.
- Nuclei are round to oval; the chromatin is finely granular with small nucleoli (so-called salt and pepper chromatin).
- Mitotic figures are scant.
- The cells and nuclei are monomorphic, rendering a monotonous aspect to this tumor, contrasting somewhat its malignant biological behavior.
Once these tumors metastasize to the liver, patients may develop the so-called carcinoid syndrome, the symptoms of which are caused by secretion of peptide hormones (e.g. serotonin, substance P, vasoactive intestinal peptide). The syndrome is marked by vasomotor disturbances causing cutaneous flushes and intestinal hypermotility leading to diarrhea, cramps, vomiting and nausea. In addition, patients may develop asthmatic bronchoconstrictive attacks. Most manifestations are thought to be caused by elevated levels of serotonin. Increased levels of serotonin and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) are detected in the blood and urine of affected patients.