Pathology: Lecture

"This is Margaret’s biopsy. See the glands? They’re 'back-to-back'—no normal stroma between them. See the nuclei? They’re hyperchromatic, elongated, stratified. And here—a mitotic figure. That cell is in the middle of dividing wrong.

And the macrophages believed it.

Now, Margaret’s tumor has a new skill: angiogenesis. It secretes VEGF, recruiting new blood vessels to feed its growth. The tumor doubles in size. It grows through the muscularis propria—the colon’s own muscle wall. pathology lecture

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." "This is Margaret’s biopsy

"This is the moment it becomes malignant. Carcinoma in situ becomes invasive adenocarcinoma. The cells learn to secrete matrix metalloproteinases—molecular scissors. They cut through the collagen. They reach the submucosa. And inside the submucosa are lymphatics and blood vessels. See the nuclei