Metastatic Merkel Cell Carcinoma In The Splenic Flexure Of The Colon Mimicking Primary Colonic Carcinoma-A Case Report With Literature Review
Bibliographic record
Abstract
Background: Merkel Cell Carcinoma (MCC) is an unusual neuroendocrine neoplasm that usually presents as a primary malignant skin tumor with localized disease.Distant metastasis is uncommon with metastases to the colon being extremely rare.In this case report, we discuss MCC metastasis to the colonic splenic flexure that mimicked primary colon carcinoma.A literature review is also undertaken.Case presentation: An 82-year-old man presented with melena and microcytic anemia accompanied by moderate weight loss.Upon investigation, a computer tomography of the abdomen showed a 5 x 3 cm apple core-type lesion at the splenic flexure.Colonoscopy revealed a circumferential ulcerated large mass in the splenic flexure which was biopsied for pathological conformation of presumed colonic carcinoma.Detailed histopathological evaluation of the endoscopic mucosal biopsies with additional immunostaining confirmed the diagnosis of metastatic MCC.Review of his medical records confirmed MCC in the right axillary lymph nodal dissection 3 years ago from an unknown cutaneous primary.Due to accompanying medical comorbidities palliative supportive management was opted.He died a month later from pneumonia and decompensated cardiac failure.Conclusion: MCC metastasis to the colon is an extremely uncommon event.Clinically and radiologically it often mimics a primary colonic carcinoma.Histopathological diagnosis from endoscopic mucosal biopsies by light microscopy alone remains a challenge.Additional immunohistochemical stains are essential for accurate diagnosis.The presence of colonic metastases probably indicates widespread disease as most cases like ours are associated with an extremely high mortality rate.Earlier diagnosis with interventional multimodality treatment options may alleviate this dismal prognosis.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".