Neuropathology

3. What are the Limitations of the Histopathological Diagnosis of Surgical Specimens?

The classification and definition of diseases can be purely academic but they also serve two practical purposes: namely interpersonal communication and prediction of a patient's outcome. If the terminologies of all diseases were standard and unified, a patient could carry that diagnosis to any physician anywhere in the world and all physicians would understand the significance of the condition and know the types of treatment that particular patient should receive. Obviously this is only the ideal. The reality is not that simple, as we all know. There are some common diseases that are familiar to most physicians. For instance, most physicians are familiar with meningiomas, which are common adult tumors, and know roughly what types of treatment are useful, even though they may not know that there are double digits of variants that may be descriptively added to the histological diagnosis. By contrast, there are many uncommon or relatively newly described conditions in which the diagnostic terms are not always precise, well established or standardized. Indeed, they are still being modified and changed from time to time as more is learned about their variations in appearance and behavior.

It is always interesting and usually helpful to know the historical transition of the concepts and changes in the terms of particular diseases but it is cumbersome and potentially confusing for neophytes. Thus, it is not uncommon to find many different or similar names given to the same condition. A new disease is usually found and defined by its discoverer. But with time, more cases are described with some variations, resulting in the modification of the definition and expansion of the diagnostic criteria until they overlap with other conditions. The borderlines between these different conditions become obscure. Consequently, arguments start as to whether they should be lumped together under one term or kept as separate entities based on some findings obtained by special diagnostic techniques. Under these conditions the diagnostic terms become ambiguous, even subjective, depending on the different training and experiences of various pathologists.

In addition, some classifications or divisions may be rather artificial, resulting in continuous debates. The best example is seen in the grading of gliomas. The line drawn between grades II and III is still controversial and one first needs to know whether the highest possible grade is grade III or IV! A similar argument concerns the reporting of the degree of cycling activity: Should one report the average (such as might be most accurately measured by flow-cytometry) or the highest percentage of cycling cells that one can find in a high-dry field? What degree of staining should one regard as "positive"? Should one actually count or just "eye-ball" it as a rough approximation? Satisfactory comments explaining the problems are required when reporting these types of results.

Another important role of diagnostic terms is to predict the outcome of a patient, so that both the physician and the patient know what to expect and what treatment would be best for the patient. The long-term outcome and the life expectancy of the average patient with a brain tumor are frequently compared with the pre-scan days, but these are not even a baseline for comparison with today's results since the clinical diagnostic criteria have changed so much. If there is advancement in the timing of diagnosis, say 4 years in the case of the usual oligoden-droglioma [14], then there had better be an increase in survival of those same 4 years before improvement in treatment can be claimed! The Will Rogers' effect all over again!

Furthermore, we are making a diagnosis from the specimen that has been removed from the patient, but the outcome of the patient really depends on what remains in the patient's CNS. That variable, plus the variety of individualized treatments, makes it difficult to evaluate the results that are currently being continuously updated. How can one begin to define the his-tological features that characterize the malignancy of a particular type of neoplasm when one starts with subtotally resected tumors, the residual volumes not measured even if solid and not measurable if infiltrating? Even the most benign such tumor will "recur", i.e. continue to grow!

Contrary to the layman's belief that all answers are there on the slides when neuropathologists look through the powerful microscope with or without special stains and even

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Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

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