Stercoral Rectal Ulceration or a Missed Diagnosis of Rectal Carcinoma: Primary Signet Ring Cell Carcinoma of the Rectum Presenting as Fecal Incontinence in an Elderly Female
Bibliographic record
Abstract
Primary signet ring cell carcinoma of the rectum is a rare entity accounting for approximately 1% of all colorectal carcinomas. It arises more frequently in the stomach and is associated with younger patient population and advanced stage on presentation. Constipation is the main factor for development of stercoral ulcer which originates as a result of pressure necrosis of the colorectal mucosa. We describe an atypical case of an elderly female with primary signet ring cell carcinoma of the rectum presenting with fecal incontinence. A 68-year old woman presented with worsening fecal incontinence and hematochezia. Rectal exam revealed a firm tissue in the lateral anal canal. The endoscopic evaluation showed a friable partially necrotic ulcerated lesion at the anorectal junction extending at least 5 cm proximally. The histologic examination of the lesion was diagnostic for a primary signet ring cell carcinoma of the rectum (positive for CK 7 and CK 20 and negative for CDX-2). Computed tomography scan of the abdomen/pelvis revealed rectal wall thickening and MRI of the pelvis demonstrated a low rectal tumor with perianal involvement, clinical T3N2 with an enlarged right external iliac lymph node. Patient received chemo-radiation and later underwent laparotomy with abdominal perineal resection and an end colostomy was performed. Patient had good clinical progress and was discharged to a skilled nursing facility. Patient had a colonoscopy done three years prior for similar symptoms and was noted to have stercoral ulcerations in the rectum but rectal biopsies at that time were unremarkable. This case highlights the following important points. Ulcers particularly stercoral ulcers may herald a concealed malignant disease, hence surveillance colonoscopy/sigmoidoscopy should be considered. Also, the diagnosis of primary rectal signet ring cell carcinoma should be investigated in the elderly presenting with the complaint of fecal incontinence.1670_A Figure 1. Colonoscopy revealed a friable, necrotic and ulcerated rectal lesion.1670_B Figure 2. CT scan demonstrated rectal wall thickening.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".