Adenocarcinoma, no specific type (NST)
— diagnostic criteria are: (a) malignant epithelial changes, in (b) a desmoplastic stroma, with (c) invasion beneath the muscularis mucosae. In practice a combination of (a) and (b) is the most useful.
— tumour area >50% mucinous component.
— worse prognosis (5-year survival decreased by 10-15%) compared with an equivalent-stage adenocarcinoma, NST, although this remains controversial.
Signet ring cell adenocarcinoma
— poor prognosis in the rectosigmoid of young or elderly people with a linitis plastica pattern of annular thickening and stenosis.
— distinguish from secondary carcinoma, e.g. gastric signet ring cell carcinoma in young females, prostate carcinoma [prostate-specific antigen (PSA) positive] in older males.
— neuroendocrine carcinoma:
carcinoid/large cell/small cell (right colon, prognosis poor)
composite adenocarcinoma and carcinoid
— adenosquamous carcinoma: caecum
— squamous cell carcinoma:
rectal: can be seen in ulcerative colitis/schistosomiasis/amoebiasis. Exclude spread from an anal carcinoma or cervical carcinoma. Need intercellular bridges ± keratinization with no gland/mucin formation
— undifferentiated carcinoma:
(a) good prognosis—medullary carcinoma. Circumscribed and expansile margin with solid sheets of tumour cells, intra- and peritumoral lymphocytes. Sporadic or in HNPCC and strongly associated with MSI-H (see below)
(b) poor prognosis—pleomorphic and diffusely infiltrative
— mixed differentiation:
e.g. adenocarcinoma (NST) with small cell carcinoma.
— metastatic carcinoma:
transcoelomic spread: stomach, ovary, endometrium, gut, pancreas direct spread: prostate, anus, cervix, kidney distant spread: breast (infiltrating lobular), malignant melanoma, lung Metastatic disease can infiltrate bowel wall and protrude into the mucosa mimicking endoscopically and macroscopically a primary lesion—a relevant previous history is crucial to diagnosis.
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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.