The final diagnosis was a colloid signet-ring cell carcinoma of the colon with lymph node involvement.
The extreme rarity of a primary colorectal signet-ring cell carcinoma metastatic to the tonsil reflects the fact that this particular histologic type of cancer occurs in only about 1% of all cases of colorectal carcinoma.
However, a PAS or PAS-D stain is not specific for the establishment of signet-ring cell carcinoma
because some signet-ring cell melanomas may show PAS+ intracellular inclusions (Table).
Primary signet-ring cell carcinoma
of the uterine cervix with long term follow-up: case report.
3,4] Saphir first described primary signet-ring cell carcinoma
of the bladder in 1955, and less than 200 cases have been reported in the literature since then.
The only histologic types of colorectal carcinoma that have been shown to have adverse prognostic significance independent of stage are signet-ring cell carcinoma
(6) and small cell carcinoma (high-grade neuroendocrine carcinoma).
Signet-ring cell carcinoma
([is greater than] 50% signet-ring cells)([sections])
4,5) High-grade tumors, such as signet-ring cell carcinomas
, small cell carcinomas, and undifferentiated carcinomas, are associated with a poorer prognosis compared with adenocarcinoma.