Languages invariably contain structures that are illogical and ideally should be altered, but almost certainly never will be. If you were designing the English language from the ground up you would never allow for so many homonyms
The English language is absolutely full of them: aid/aide, ail/ale, air/heir, aisle/I'll, ate/eight, blue/blew, bare/bear, etc, etc, etc. They make it extremely difficult to learn English as a first language, let alone as a second.
Likewise, the language of pathology contains more than its fair share of fuzzy or downright inappropriate terminology which all trainees must master. "Pyogenic granuloma" is neither pyogenic nor granulomatous. In spite of the clear demonstration that these are lobular capillary hemangiomas with overlying nonspecific granulation tissue, the term continues to be used. Change does occasionally come, albeit slowly. Witness the gradual decline in the use of "malignant fibrous histiocytoma," a designation for high-grade sarcomas devoid of demonstrable mesenchymal differentiation that is widely known to be inaccurate (sorry Dr. Stout). The use of more modern techniques has wittled away many MFH's that can now be shown to display at least abortive stromal differentiation, and the remaining tumors are more appropriately designated as "undifferentiated pleomorphic sarcomas."
And then there are the eponyms
of pathology. First, there's the whole apostrophe thing. I'm a firm believer that where these have historically been possessive designations, ie. Hodgkin's disease, the apostrophe should remain, but the world seems to disagree, and most of us don't seem to understand how to use the apostrophe anymore anyway. How often have you seen "it's" as the possessive form of "it," when "its" is correct and "it's" means ONLY the contraction "it is?" Dropping the apostrophe creates its own set of problems. How often have you seen "Wilm tumor?" His name was, after all, Dr. Max Wilms. I generally applaud established eponyms because they are an excellent short-hand way to convey information. In some instances, we don't even HAVE another designation. Wilms' tumors are nephroblastomas, but what else would we call Hodgkin's disease?
If you want to become an eponym, some helpful guidelines may be in order. First, you need to describe something never seen or at least never before popularized. In that regard, it may have been much better to have been born a hundred years ago when there were many more things left to be described, but fear not, there are still unknowns out there waiting for you and you have many more tools at your disposal today. Second, you need to give the "thing" a VERY LONG AND CUMBERSOME NAME. For example, Dr. Krukenberg called his tumor, "fibrosarcoma ovarii mucocellulare carcinomatodes". Note that it is NOT at all necessary to be correct in your designation. Dr. Krukenberg thought his tumor was a primary ovarian sarcoma. Wrong on both counts. He missed the gastrointestinal signet-ring adenocarcinoma primaries. The long name really seems to be the key. For example, "Small cell tumor of the thoracopulmonary region in childhood" just BEGS to be called "Askin's tumor," it's a lot shorter and easier to remember. "Bizarre parosteal osteochondromatous proliferation" was destined to become the far shorter "Nora's lesion." Likewise, "sinus histiocytosis with massive lymphadenopathy" seems like a setup for an eponym, even the somewhat long and hyphenated one of "Rosai-Dorfman disease." Conversely, verrucous carcinoma is often referred to as "Ackerman's tumor," yet this designation has never fully replaced the short and easy to remember original designation. Perhaps the ratio of the length of the original designation to the length of the author's last name gives some probability measure for the chance of an eponym succeeding as the new term. Ackerman should have called his tumor something like, "non-metastasizing locally destructive cytologically benign squamous proliferation with verrucous surface."
The next part is trickier. Someone else has to first refer to the tumor that you described by your name in a published work. I have few hints here. Luck, money, a reverent former trainee, or other considerations may be involved. There may be a substantial period of time between your description of an entity and its eponymous designation. Fritz Brenner described his tumor in 1907, but it was 1932 before Robert Meyer coined the term, "Brenner's tumor." Actually, I think he called it a "Brenner tumor" without the apostrophe; at least that's been the popular designation even before the current apostrophe witch hunt, as with Krukenberg tumor.
It seems appropriate that eponyms be granted only one per pathologist to prevent confusion. Witness the term, "Paget's disease" for example. A modifier is required to indicate whether this is "of bone," "of nipple," or "extramammary." Clearly James had too much of a good thing.
Eponyms are not awarded based on merit. Many famous pathologists richly deserving of the honor have not received it. There are no eponymous entities (that I am aware of) named for Virchow (although he does have his own journals), Stout, Scully, Dahlin, Enzinger, or Helwig, to name but a few deserving individuals who between them have described literally hundreds of new entities. In fact, their productivity probably worked against them. When you have personally described dozens of entities, which one should become "your entity?" Confusion begets indecision and the answer becomes, "none."
Although eponyms might be considered to grant their designee some measure of immortality, they may, in fact, have a finite lifespan if our understanding of the original entity changes measureably. Drs. Krukenberg, Hodgkin, and Brenner seem destined for immortality, but Drs. Ewing and Askin have seen their tumors absorbed under the PNET rubric. C'est La Vie.