Histological Type

More than 90 % of gall bladder cancers are adenocarcinoma. Adenocarcinoma

— tubular/acinar: usual type and a well to moderately differentiated biliary pattern of low cuboidal to tall columnar cells.

— papillary: polypoid/well differentiated/better prognosis.

— intestinal/mucinous/signet ring cell/clear cell: unusual. Distinguish from metastatic stomach or bowel cancer by adjacent mucosal dysplasia. Mucinous/signet ring cell carcinomas require >50% of the tumour to be composed of this pattern.

Adenosquamous carcinoma

Squamous carcinoma

Small cell carcinoma

— and other neuroendocrine lesions, e.g. carcinoid/large cell neuroendocrine carcinoma including composite tumours (carcinoid/ adenocarcinoma).

— small cell carcinoma is aggressive and may be a component of usual adenocarcinoma.

Spindle cell carcinoma/carcinosarcoma

— biphasic carcinoma/sarcoma-like components ± specific mesenchymal differentiation. These represent carcinomas with variable stromal differentiation and overlap with undifferentiated carcinoma.

— elderly patients, poor prognosis.

Undifferentiated carcinoma

— nodular and solid/spindle cell/giant cell/osteoclast-like giant cell variants.

Malignant melanoma

— secondary (15% of disseminated melanoma at autopsy) or rarely primary (nodular, adjacent mucosal junctional change).

Metastatic carcinoma

— direct spread: stomach, colon, pancreas, cholangiocarcinoma.

— distant spread: breast, lung, kidney.

Note that cystic duct carcinoma is classified as a tumour of the extra-hepatic bile ducts.

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