Case Presentation: A 47 year old woman with Lynch syndrome presented with only intermittent abdominal discomfort and mucus in her stools for several months. Colonoscopy showed patchy erythema in the cecum and the transverse colon. The pathology revealed high-grade dysplasia with focal intramucosal signet ring cell carcinoma. Immunohistochemical stains were positive for CD68, CDX2, pankeratin and p53. Tumor markers CA 15-3, CA 19-9, CA 125, CEA and PET scan were negative. She underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy and subtotal colectomy.
Patient recovered well after having a successful surgery for a multifocal intramucosal signet ring cell carcinoma involving the cecum, the ascending colon and the transverse colon. All lymph nodes were removed and all negative. Final staging was pTisN0. CT chest/abdomen/pelvis showed no evidence of recurrent, residual or metastatic malignancy.
Discussion: Primary SRCC of the colon was first described in 1951 by Laufman and Saphir. SRCC is a very rare type of colorectal carcinoma with incidence 0.1% to 2.6% of all colorectal cancers. The third leading cause of death in the US is colorectal adenocarcinoma (CRC), typically occurs in men ages fifties to sixties, with only 20% of cases found in patients younger than fifty. A histologic subtype of CRC is SRCC which has distinct molecular and tumor biology from adenocarcinoma and is extremely rare and associated with poorer prognosis compared to other subtypes. About 96% of SRCC are found in the stomach, it rarely is seen in colon, rectum, gallbladder, pancreas, prostate, urinary bladder, and breast and or pharyngeal salivary glands.
An association between ulcerative colitis and SRCC of colorectum has been suggested. Ojeda reported that 12% of patients had ulcerative colitis and primary colorectal SRCC. This patient described had no inflammatory bowel disease.
Positive family history is a risk factor for colorectal cancer. However, it may not be a predictive factor for SRCC. This may be attributed to the rarity of cases or variability of tumor burden. This patient described had no family history of colorectal cancer.
Histopathology of SRCC reveals peripheral accumulation of the mucinous component given the signet ring characteristic. SRCC is more aggressive than other colorectal carcinoma histological subtypes and are diagnosed at advanced stages due to deceptive and insidious onset. SRCC is characterized by intracytoplasmic mucin production that causes the nucleus of the cell to be displaced to the periphery attributing it the characteristic ‘signet ring’ appearance. SRCC can permeate the entire wall of affected sites causing rigid and contracted structures known as “Linitis-plastica”.
Conclusions: Characteristically primary SRCC presents in advance stages of disease, at younger age groups, may have peritoneal dissemination, lymphatic spread, with or without liver metastasis and hence has a poor prognosis. The intramucosal tumor spread with relative sparing of the mucosa accounts for minimal symptoms and often heme-negative stools which is confounding. This tumor has radiographic tumor resemblance to inflammatory processes or even simple scope trauma on EGD.
The overall prognosis is poor with a 5-year survival of SRCC of the colon varies between 0 to 12%, depending on the staging of the lesion. Surgical resection is the only curative treatment with excellent outcome if done at early stages.