Carcinoid tumour

— yellow/nodular/±multifocal.

— chromogranin/synaptophysin/CD56 positive.

— typically insular pattern of uniform cells in a dense fibrous stroma with vascular thickening.

— 20% have carcinoid syndrome implying liver metastases: facial flushing/asthma/thickening of cardiac valves due to release of the vasoac-tive peptides (e.g. serotonin) into the systemic circulation.

— low-grade malignancy: any functioning well-differentiated tumour; any tumour with angioinvasion; non-functioning tumour >2 cm or with invasion beyond the submucosa.

— high-grade malignancy: tumour with a high mitotic rate, cellular atypia or necrosis and poorly differentiated tumours/small cell carcinomas.

Carcinoid tumour has an overall 5-year survival rate of 50-65%. It is better for small lesions [metastatic rate: <1 cm (2%), 1-2 cm (50%), >2 cm (80%)] confined to the wall (85%) than those invading the serosa or beyond (5%). Metastases are to regional nodes and liver (multiple, solid/cystic): also bone, skin and thyroid. The above comments relate mostly to classical EC cell jejuno-ileal carcinoids. Duodenal carcinoids have a better prognosis, occur mainly in D1/D2 and include nonfunctioning G cell tumours, gastrinomas (Zollinger Ellison/MEN syndromes), somatostatinoma and gangliocytic paraganglioma.


— rare: adenosquamous, sarcomatoid carcinoma; aggressive. Metastatic carcinoma

— direct spread: colorectum, ovary, stomach, pancreas.

— distant spread: lung, breast and choriocarcinoma.

The bulk of disease is extramural but tumour can invade muscularis and mucous membrane causing obstruction or perforation and mimicking a primary lesion. Adjacent mucosal dysplasia is a useful pointer and adenoma is present in 24% of primary lesions. Small bowel is a common site of metastatic malignancy with formation of peritoneal seedlings, multiple nodules, plaques and strictures causing obstruction.

Metastatic melanoma

— pigmented/multifocal.

— amelanotic/oligomelanotic.

— melanoma requires confirmation with S100, HMB-45, melan-A.

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