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Psammoma bodies have been documented in carcinoid tumours of the duodenum, but not in carcinoids at other sites in the gastrointestinal tract.1,2 We describe a psammomatous carcinoid tumour in the rectum.
A 50 year old woman presented with a two month history of abdominal pain and bleeding from the rectum. On examination, she had pallor, in addition to fullness and tenderness in the left iliac fossa. There was no evidence of mass or free fluid in the abdomen on abdominal examination. Rectal examination revealed a growth approximately 5 cm above the anal verge. Her erythrocyte sedimentation rate was 80 mm at the end of the first hour and she had a neutrophilic leucocytosis. Her liver function tests were largely unremarkable, except for a mild increase in transaminases (less than two times upper limit of normal). Flexible sigmoidoscopy showed a large ulcerated friable growth involving more than 50% of the bowel circumference.
Biopsy of the tumour showed a neoplasm composed of glandular structures with individual cells having round, uniform nuclei with a “salt and pepper” appearance. Abundant psammoma bodies were seen throughout the biopsy (fig 1). Immunohistochemistry with antibodies to synaptophysin (Dako, Glostrup, Denmark; 1/100 dilution) and chromogranin (Dako; 1/100 dilution) showed cytoplasmic staining. The features were those of a glandular carcinoid, with extensive psammomatous calcification. An abdomino-perineal resection was planned. At surgery, the patient was found to have extensive inoperable disease. A sigmoid colectomy with colostomy (Hartmann’s procedure) was performed to relieve her obstruction. The sections through the resected colon showed similar histological features—that is, a glandular carcinoid with psammoma bodies. The tumour infiltrated the full thickness of the bowel wall. Two regional lymph nodes contained metastatic carcinoid tumour.
Carcinoid tumours of the gut are classified, based on site of origin, into foregut (stomach and duodenum), midgut (small intestine and proximal colon), and hindgut (terminal intestine and rectum) tumours. Psammoma bodies have been described in about 15–20% of carcinoid tumours of the duodenum and are found almost exclusively at the ampulla of Vater.2 Most of these are histologically characterised by glandular structures and psammoma bodies.1,2 These neoplasms often express somatostatin by immunohistochemistry and are termed somatostatinomas.3 They rarely result in the somatostatinoma syndrome of diabetes mellitus, cholelithiasis, and steatorrhoea, which is commonly seen with pancreatic somatostatin containing neuroendocrine tumours.4 An association has also been reported between psammomatous carcinoid of the duodenum and neurofibromatosis.4,5 The rectum is not an uncommon site for carcinoids. However, they are conventional carcinoids and display solid sheets, ribbons, and trabeculae or gland-like structures composed of round cells with monotonous nuclei and stippled chromatin. Psammoma bodies have not been documented in rectal carcinoids previously. The reason for this predilection of psammoma bodies for foregut carcinoids is not known.