Reappraisal of the so-called 'villous tumours' of the rectosigmoid, based on histological, immunohistochemical and genotypic features

Rapid Malignant Transformation of Tubulovillous Adenoma, Initially Presenting as McKittrick-Wheelock Syndrome: A Case Report

Most cases of colorectal cancer develop from adenomatous polyps, slowly progressing within an average period of 8-10 years. McKittrick-Wheelock syndrome (MKWS) is a rare manifestation of tubulovillous adenoma. It generally presents as hypersecretory diarrhea with severe electrolyte and fluid depletion. Roughly, 5% of the published cases have reported malignant histopathology associated with MKWS, with little to no data regarding the malignant transformation process of those patients. Our patient was a 53-year-old Asian woman suffering from chronic secretory diarrhea, resulting in severe volume, electrolyte depletion, and prerenal azotemia, consistent for MKWS. Her symptoms initially improved with sulfasalazine but eventually worsened. She demonstrated signs of systemic (elevated leukocyte, CRP, and LDH) and local inflammation (dense lymphocyte infiltration in colorectal tissue) throughout the course of her disease. Serial pathological results showed rapid neoplastic progression of adenomatous polyp to adenocarcinoma within 1 year period. Surgical resection resulted in complete symptom resolution. Molecular examination showed a favorable profile of exon 4 Kirsten rat sarcoma viral oncogene homolog mutation, normal NRAS, BRAF, CDX2, and CK20 expressions. Her molecular pattern did not reflect the profile of an aggressive disease, suggesting the possibility of oncogenic processes outside the major pathways of adenoma to carcinoma progression. Chronic inflammation is a well-established risk factor for colorectal cancer, and prostaglandin E2 (PGE2) has been observed as one of the key regulators of tumor initiation and growth. PGE2 is also responsible for hypersecretory diarrhea associated with MKWS.

Factors Associated With Classification of Hyperplastic Polyps as Sessile Serrated Adenomas/Polyps on Morphologic Review

BACKGROUND

Distinguishing sessile serrated adenomas/polyp (SSA/P), a subset of serrated polyps, from hyperplastic polyps (HPs) remains a challenge and has surveillance implications. Our goal was to identify clinical and pathologic factors associated with serrated polyps originally read as HPs being reassessed as SSA/Ps versus confirmed as HPs.

METHODS

Data were collected from consecutive patients with a right-sided HP and a corresponding comparison group with conventional adenomas between 1993 and 2003. Two experienced gastrointestinal pathologists, blinded to polyp and clinical factors, reinterpreted the HPs using current SSA/P classification criteria. These HPs were classified as SSA/P when diagnostic histologic feature(s) were present in at least 3 crypts. Analyses, conducted on a per polyp basis, examined the factors associated with risk of individual HPs being reassessed as SSA/Ps as opposed to being confirmed as HPs.

RESULTS

Of the 702 HPs (355 adults), 188 (26.8%) were reclassified as SSA/Ps. Predictors of HPs being reinterpreted as SSA/Ps included: size ≥5 mm [odds ratio (OR), 2.09; 95% confidence interval (CI), 1.34-3.26], proximal location (OR, 2.83; 95% CI, 1.69-4.74), synchronous adenomas with advanced pathology (OR, 2.61; 95% CI, 1.22-5.55) and ≥1 synchronous HPs (other than HP being reassessed) reclassified as SSA/Ps (OR, 11.76; 95% CI, 6.75-20.49).

CONCLUSIONS

Because HP versus SSP is not very reproducible the predictors of SSA/P that we identified, including size, location, and synchronous lesions, can offer some additional help to endoscopists when determining surveillance intervals in patients with serrated polyps. In addition, observed association between SSA/P with advanced conventional neoplasia (but not low-grade adenomas) suggests 2 distinct groups of patient predisposition, one with both advanced conventional and important serrated precursors (SSA/P) and the other largely restricted to nonadvanced conventional adenomas and HPs only. Whether the association reported here has to do with SSA/P diagnosis per se or generally larger size of SSA/P remains to be determined in future studies.