It's always exciting when our understanding regarding some aspect of medicine or pathology undergoes a radical change. When I was an undergraduate science student, I don't think my professors, who were otherwise excellent, did as good a job as they could have at listing the questions that remained to be answered or areas in which our thinking might radically change in science. So it is with pathology. Our trainees are apt to think that all of the "good stuff" has already been discovered and cataloged. This is far from the case. The reality is that we don't know what we don't know and, in addition, we don't know what we know incorrectly.
For generations gastric ulcers were absolutely "known" to be due to excess gastric acid secretion and a variety of surgical procedures were developed to decrease acid secretion and increase gastric emptying. These procedures were variably successful. Then two Australians, Robin Warren, a pathologist, and Barry Marshall, a young gastroenterologist, turned the medical world upside down by convincing even the skeptics (and there were many) that gastric ulcers were an infectious disease. They were justly awarded a Nobel prize for this work, one of the very few involving a pathologist. Today we all observe Helicobactor pylorii organisms in gastric biopsies. They were always there, waiting for their significance to be discovered, and greatly rewarding those who made the mental leap.
Most of the time, unfortunately, changes in treatment are slow in coming after radical changes in understanding. For generations surgeons "knew" that cancer spread by tiny fingers of tumor growing out from the main tumor mass (cancer -> the crab), and the way to cure the disease was with locally radical surgery. Breast cancer, regardless of tumor size, was treated by the Halsted radical mastectomy with removal of chest wall musculature, soft tissue sarcomas, even small ones, were treated by amputations, etc. With time it became clear that cancers could spread by direct extension but the development of embolic lymphovascular metastases was typically the life threatening factor and these metastases often occurred before the primary tumor was even detected. Local cancer resections became more limited and tailored to individual tumor locations and size. Yet, it took decades for this change to come about and even now it is not complete. Witness the huge local resections still typically done for cutaneous malignant melanomas, yet, with the exception of a few variants such as desmoplastic melanoma, local control never has been the issue with this disease.
For years, we pathologists all "knew" that pseudomyxoma peritoneii (aka "jelly belly") developed from low-grade ovarian mucinous neoplasms. Only in the last decade or so has it become clear that the vast majority of low-grade mucinous tumors involving the ovary and the peritoneum arise from the appendix (who would have guessed!). Yet we still receive ovarian resection specimens for mucinous neoplasms where the surgeon has not removed the appendix.
Within the past several years pathologists have been overturning another "truth" of ovarian pathology, that serous ovarian carcinomas arise from ovarian surface inclusions. It is becoming increasingly clear that most (?almost all) high-grade ovarian and peritoneal serous carcinomas in fact arise from the fallopian tube, particularly the fimbrae of the tube. In the current Featured Articles section of Pathology Network is an article from AJSP posing the question, "Are all pelvic (nonuterine) serous carcinomas of tubal origin?"
The data are becoming overwhelming. One wonders how long it will be, though, before gynecologic surgeons leave the ovaries in place and remove only the fallopian tubes prophylactically when doing hysterectomies for non-ovarian pathology in pre-menopausal women.
....and from where will the next big shift in thinking come?