Primary signet-ring cell carcinoma of the colon and rectum

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Abstract
Colorectal signet-ring cell carcinoma (SRCC) is uncommon; discordant data have been previously reported about clinicopathologic features. Thirty-four cases of primary colorectal SRCC were retrospectively reviewed to clarify controversies. Primary colorectal SRCC was diagnosed when the following criteria were satisfied: 1) the tumor was primary; 2) histologic material was adequate; 3) signet-ring cell represented more than 50 percent of the cancer. We identified 34 cases (1.1 percent) of 2,995 consecutive large bowel cancers collected at the Institute of Anatomic Pathology of Florence between 1985 and 1993. Patients ranged in age from 31 to 89 (mean, 63.5; median, 65) years; 19 were male, and 15 were female (male:female = 1.3:1). Fifteen tumors were located in the proximal colon, 11 in the rectum, and 8 in the distal colon. The gross shape was infiltrative in 24 cases and exophytic in 10; only 6 cases (17.6 percent) showed features of linitis plastica. Most cancers (61.8 percent) were Stage C, 29.4 percent were Stage B, and distant metastases were present in only three cases (8.8 percent). No Stage A case was found. Prognosis was extremely poor, and overall five-year survival rate was 9.1 percent. Survival was influenced significantly by tumor stage (P < 0.01). Comparison of our data with the literature showed many differences that could be related to different applied diagnostic criteria. We underlined the importance of histology as reproducible criterion for diagnosis of primary colorectal SRCC.