Bladder-Adherent Primary Appendiceal Carcinoma Masquerading as a Carpeting Rectal Lesion Detected by a Fecal Immunochemical Test: A Case Report
Bibliographic record
Abstract
Introduction: Primary appendiceal carcinoma is rare and comprises up to 1% of all colorectal malignancies. Its invasion into adjacent organs, such as the bladder and rectum, especially as a presenting characteristic, is even less common. Case Presentation: A 75-year-old asymptomatic male tested positive on a screening fecal immunochemical test (FIT). Colonoscopy showed a rectosigmoid tumor and normal appendiceal orifice. Staging MRI surprisingly showed that the cancer was, in fact, of appendiceal origin, coursed posteriorly to invade the rectosigmoid and form adhesions with the urinary bladder. Staging CT did not show metastatic disease. Low anterior resection, en bloc appendectomy, and right hemicolectomy were performed along with cystectomy and ileal conduit. Hematoxylin and eosin stains showed appendiceal adenocarcinoma invading through the appendiceal wall into the rectal muscularis and submucosa. Features of neuroendocrine carcinoma were not identified on immunohistochemistry. This was a colonic type of adenocarcinoma of the appendix. Conclusion: This is a rare case of appendiceal carcinoma invading the rectum and presenting as a positive screening fecal immunochemical test in an asymptomatic individual. We effectively demonstrate the use of preoperative MRI to identify the appendiceal origin of the tumor, as well as to demonstrate the extent of tumor spread, which assisted with operative management and treatment planning.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".