Diffuse (signet-ring) gastric carcinoma
by Evelyn Bruner, M.D.
Adenocarcinoma accounts for 90-95% of all malignant tumors of the stomach and is the second leading cause of cancer death worldwide. One of the reasons is that gastric adenocarcinoma is often asymptomatic and when symptomatic, causes nonspecific symptoms in its earliest stages and by the time stomach cancer is diagnosed it has often already metastasized.
Figure 1 depicts the primary diffuse gastric adenocarcinoma. This carcinoma is composed of discohesive, pleomorphic malignant cells. Prominent in this type of cancer is the “signet-ring” cell which possesses a prominent intracytoplasmic mucin vacuole that peripherally displaces the nucleus (arrow).
Figure 2 depicts leptomeningeal carcinomatosis. This is defined as an infiltration of the carcinoma cells in the arachnoid and subarachnoid space. This is a serious complication occurring in approximately 5-8% of all cancer patients and only less than 1% of gastric cancer patients. Spread to the leptomeninges can occur at any stage in a neoplastic disease, as the presenting sign or as a late complication. Presenting symptoms are nonspecific and can include headache, nausea, vomiting, and ataxia. Progressive blindness or bilateral hearing loss can also be seen.
Figure 3 depicts metastases to the left ovary, also knows as a Krukenberg tumor. This is an uncommon metastatic tumor of the ovary, most often found in both ovaries (80%), but metastases to a single ovary can occur as was seen in this case. Classically, these are composed of morphologically similar discohesive, malignant signet-ring cells (arrow) as seen in the primary carcinoma. Stomach is the primary site in most cases (~70%) but metastases from other locations within the GI tract and from the breast can occur. Although the exact mechanism of spread is not known, it is postulated that the most likely route is retrograde lymphatic spread.
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