Pathology Lecture -

"At this point, Margaret felt nothing. The polyp was a tiny mushroom growing in the dark. But on a colonoscopy, it would have looked like a raised red bump. If we had caught it then, we would have snip-snipped it out. Case closed. We didn't." Part 2: The Invasion (Breaking the Basement Membrane) An animation shows cells piling up, pushing through a thin blue line (the basement membrane).

The autopsy—which I performed—showed a 4 cm liver metastasis that had replaced 60% of her liver parenchyma. The primary colon tumor had perforated silently, walled off by the omentum. And here’s what matters: we found two tiny metastases in her lungs, each 2 mm. Too small to see on CT. That’s why she didn’t respond fully to chemo—the disease was always one step ahead." pathology lecture

APC normally says, 'Stop dividing.' Without it, the cell becomes hyperplastic. Not cancer yet. Just... enthusiastic. A polyp. Benign. But now that cell is unstable. It divides faster than its neighbors. It acquires more mutations: KRAS (the accelerator stuck to the floor), then TP53 (the cell’s suicide switch, disabled)." "At this point, Margaret felt nothing

And the macrophages believed it.

"Margaret’s primary tumor was 7 cm. It had invaded the omentum—that fatty apron of the abdomen. That’s what she felt as a lump. The omentum tried to wall it off, but the tumor just grew inside it like ivy on a fence." Part 4: The Diagnosis (The Biopsy) The slide changes to a histology image: disorganized glands, dark purple nuclei, mitotic figures. If we had caught it then, we would have snip-snipped it out

Yesterday, I signed out her case. Let’s go back to the beginning." The slide changes. A diagram of a normal colon lining—orderly, like bricks in a wall.

"Margaret chose palliative chemo. She had eight good months. Then the liver metastases grew. She developed ascites—fluid in the belly from portal hypertension. Then jaundice—the liver couldn’t clear bilirubin. Then confusion—ammonia from the gut bypassing the failed liver.