Histopathology
Histopathology is a branch of histology and pathology that studies and diagnoses diseases on the tissue and cellular level. While histopathology is closely related to cytopathology, the main difference is diagnostic information gained from histopathology is acquired from solid tissue samples, whereas specific disaggregated cell preparations are used in cytopathology.[1] Typically a biopsy or surgical specimen is examined by a pathologist after the specimen has been processed and histological sections have been placed onto glass slides.
Rudolf Ludwig Karl Virchow is considered by many to be one of the fathers of cellular pathology, remembered most for his collection of lectures on the topic, published as Cellular Pathology in 1858.[2][3] However, his assistant, David Paul von Hansemann also played an important role in the progress of histopathology during the 1890s, producing his book The Microscopic Diagnosis of Malignant Tumours and other important research.[4][5]
Testing
Collection
Tissues are collected typically by a type of biopsy (removal of tissue from a living subject), though other methods may be used. The type of biopsy used is often determined by the region where tissue will be removed. For example, a core biopsy may target muscle tissue via a large-bore needle. A cone biopsy targets a woman's cervix, while a Pipelle biopsy targets the endometrium, which is the inner mucous membrane of the uterus. Other types of collection include currettings, scrapings of tissue from the disease site; resectioning, a complete removal of diseased tissue; and even amputation, the complete removal of an extremity.[1]
Preparation
Fixation and sectioning
The first step of preparation is fixation, the process of placing the sample in a particular preservative substance and appropriate container for transport and/or distribution. The most commonly used fixative is 10 percent neutral buffered formaldehyde, a toxic organic compound with the formula CH2O or HCHO. Some samples may require freezing, while other special tissues like bone marrow and special procedures like electron microscopy require special fixatives. This step is vital to the diagnostic process. Without a proper fixative, tissues can degrade to the point of producing poor diagnostic sensitivity.
After the fixed sample is received, it may be bisected (smaller sample) or sectioned into blocks (larger sample) to facilitate processing and embedding. If sectioned into blocks, the resulting tissue samples may then be placed in cassettes for later ease of analysis.[1]
Dehydration, clearing, and impregnation
Staining
Examination
References
- ↑ 1.0 1.1 1.2 Evans, David; Robinson, Max; Orchard, Guy (ed.); Nation, Brian (ed.) (2011). "Chapter 1: What is Histopathology?". Histopathology. Oxford University Press. pp. 1–33. ISBN 9780199574346. http://books.google.com/books?id=qWScAQAAQBAJ&pg=PA3. Retrieved 18 April 2014.
- ↑ "Rudolf Virchow — father of cellular pathology". Journal of the Royal Society of Medicine 86 (12): 688–689. December 1993. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1294355/?page=1. Retrieved 17 April 2014.
- ↑ Virchow, Rudolf Ludwig Karl (1860). Cellular Pathology as Based Upon Physiological and Pathological Histology. John Churchill. http://books.google.com/books?id=nmEGHJy9uswC&printsec=frontcover. Retrieved 17 April 2014.
- ↑ Bignold, Leon P.; Coghlan, Brian L. D.; Jersmann, Hubertus P.A. (2007). David Paul von Hansemann: Contributions to Oncology: Context, Comments and Translations. Springer. p. xii. ISBN 9783764377694. http://books.google.com/books?id=i2fEpOXxgvkC&pg=PR12&lpg=PR12. Retrieved 18 April 2014.
- ↑ Edmundson, Walter F. (February 1948). "Microscopic Grading of Cancer and Its Practical Implication". Archives of Dermatology and Syphilology 57 (2): 141–150. doi:10.1001/archderm.1948.01520140003001. http://archderm.jamanetwork.com/article.aspx?articleid=521834. Retrieved 18 April 2014.
