Much has changed in the world of diagnostic anatomic pathology and much has not
Diagnostic anatomic pathology as a specialty in medicine encompasses the practice of general surgical pathology, cytopathology, and autopsy pathology. Additionally, there are now anatomic pathologists who practice part-time or full-time in these subspecialty areas: hematopathology (hematology), dermatopathology, molecular genetic pathology, pediatric pathology, neuropathology, forensic pathology, bone/soft tissue pathology, breast pathology, liver and gastrointestinal pathology, lung pathology, transplant pathology, gynecologic pathology, head and neck pathology, genitourinary pathology, renal pathology, ophthalmic pathology, and more! Board certification exists for the first six of these subspecialty areas as well as for anatomic pathology and cytopathology
What has not changed is the foundation for diagnosis in anatomic pathology. This foundation has historically been gross (macroscopic) examination of tissues and light microscopic examination of hematoxylin and eosin-stained tissue sections and cells, such as those procured from biopsies and surgical resections. These approaches continue to dominate the diagnostic anatomic pathology world and possess so much power that they will likely continue to used as diagnostic tools well into the future.1
What has changed in this era of molecular medicine is that the pathologist’s diagnostic tool box has expanded to include techniques that allow for diagnostic characterization of disease processes at the molecular level. The targeted identification of specific molecules for diagnosis actually began in the 1980s with the advent of diagnostic immunohistochemistry. This technique makes it possible to simultaneously visualize cell type and differentiation markers in standard tissue sections by light microscopy and has revolutionized diagnostic surgical pathology. It is extremely valuable in diagnostic typing of cancers, even in small needle core biopsies and can help, in selected cases, confirm a histological diagnosis of malignancy in needle core tissue, such as in the case of small prostate cancers (see the article Prostate Cancer Diagnosis in this issue). Molecular genetic pathology diagnostic tools were initially applicable only to fresh or frozen cells and tissues but now can be routinely used in formalin-fixed, paraffin-embedded tissues, which is the common state of biopsy and resection tissues available for analysis. These molecular pathology diagnostic tools are discussed in-depth in Dr. John Pfeifer’s article in this issue. Molecular genetic pathology diagnostics have had a major impact on the diagnosis of many cancers, particularly leukemias and lymphomas and some soft tissue sarcomas. For example, the World Health Organization classification of many leukemias and lymphomas is based on a combination of light microscopic features (morphology), immunophenotype, and molecular genetics
Yet, for many non-neoplastic diseases and most solid tumors, light microscopy is still the gold-standard. This is evident in the articles in this issue on prostate cancer diagnosis, biopsy diagnosis of hepatitis, and melanoma diagnosis. In the future, molecular pathology diagnostics will become increasingly useful in difficult diagnostic cases, in risk stratification of patients, and in prediction of response to specific therapies
In this issue of Missouri Medicine, the Division of Anatomic and Molecular Pathology in the Department of Pathology and Immunology at Washington University School of Medicine presents five articles covering a range of diagnostic issues addressing important diseases (melanoma, prostate cancer, hepatitis) and diagnostic tools (the autopsy, molecular genetics)
In the article entitled, “Melanoma: From Patient Presentation to Pathology Report,” Drs. Omar Jassim and Anne Lind provide a combined dermatology-dermatopathology roadmap for diagnosis of melanoma from clinical presentation to histopathologic diagnosis. Similarly, in the next article, “Prostate Cancer Diagnosis,” by Drs. Peter Humphrey and Gerald Andriole, the clinical and histological diagnoses of prostate cancer, with outcome implications, are presented from a combined urology-urologic pathology standpoint. In the article on “Biopsy Diagnosis of Hepatitis,” Dr. Elizabeth Brunt focuses her attention on the importance and role of the liver biopsy in the diagnosis of patients with hepatitis. The next article by Dr. Louis Dehner, “The Medical Autopsy: Past, Present and Dubious Future,” speaks to the history of the autopsy and its current relevance. The final article by Dr. John Pfeifer, “Molecular Pathology and Patient Care,” highlights the everyday value of molecular pathology in the diagnosis and hence care of patients
In these articles one can gain a current perspective on use of time-tested diagnostic tools that are still the cornerstones of modern diagnostic pathology as well as how molecular pathology is playing an increasingly important role in this era of molecular medicine
Acknowledgment
Special thanks to Dr. John Pfeifer for his skill in helping edit these articles
Biography
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Peter A. Humphrey, MD, PhD, MSMA member since 2008, is Ladenson Professor and Chief of Anatomic and Molecular Pathology at Washington University School of Medicine in St. Louis.
Contact: ude.ltsuw.htap@yerhpmuh
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References
1. Rosai J. Why microscopy will remain a cornerstone of surgical pathology. Lab Invest. 2007;87:403–408. [PubMed] [Google Scholar]
