Koilocyte: Difference between revisions
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== Pathogenesis == |
== Pathogenesis == |
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The atypical features seen in cells displaying koilocytosis result from the action of the E5 and E6 [[oncoproteins]] produced by HPV. These proteins break down keratin in HPV-infected cells, resulting in the perinuclear halo and nuclear enlargement typical of koilocytes.<ref>{{Cite journal|date=2015|editor-last=Shurin|editor-first=Michael R.|editor2-last=Thanavala|editor2-first=Yasmin|editor3-last=Ismail|editor3-first=Nahed|title=Infection and Cancer: Bi-Directorial Interactions|url=http://dx.doi.org/10.1007/978-3-319-20669-1|doi=10.1007/978-3-319-20669-1}}</ref> The E6 oncoprotein, along with E7, is also responsible for the dysregulation of the cell cycle that results in squamous cell [[dysplasia]]. The E6 and E7 oncoproteins do this by binding and inhibiting the [[tumor suppressor genes]] p53 and RB, respectively. This promotes progression of cells through the cell cycle without appropriate repair of DNA damage, resulting in dysplasia.<ref>{{Citation|last=Klatt|first=Edward C.|title=The Female Genital Tract|date=2010|url=http://dx.doi.org/10.1016/b978-1-4160-4930-2.00034-7|work=Robbins and Cotran Review of Pathology|volume=|pages=v|publisher=Elsevier|isbn=978-1-4160-4930-2|access-date=2020-11-12|last2=Kumar|first2=Vinay}}</ref> Due to the ability of HPV to cause cellular dysplasia, koilocytes are found in a number of potentially precancerous lesions. |
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== Lesions containing koilocytes == |
== Lesions containing koilocytes == |
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Revision as of 00:22, 12 November 2020
A koilocyte is a squamous epithelial cell that has undergone a number of structural changes, which occur as a result of infection of the cell by human papillomavirus (HPV).
Koilocytosis
Koilocytosis or koilocytic atypia or koilocytotic atypia are terms used in histology and cytology to describe the presence of koilocytes in a specimen.[1]
Koilocytes may have the following cellular changes:
- Nuclear enlargement (two to three times normal size).
- Irregularity of the nuclear membrane contour.
- A darker than normal staining pattern in the nucleus, known as hyperchromasia.
- A clear area around the nucleus, known as a perinuclear halo or perinuclear cytoplasmic vacuolization.[2]
Collectively, these types of changes are called a cytopathic effect; various types of cytopathic effect can be seen in many different cell types infected by many different viruses.[2] Infection of cells with HPV causes the specific cytopathic effects seen in koilocytes.
Pathogenesis
The atypical features seen in cells displaying koilocytosis result from the action of the E5 and E6 oncoproteins produced by HPV. These proteins break down keratin in HPV-infected cells, resulting in the perinuclear halo and nuclear enlargement typical of koilocytes.[3] The E6 oncoprotein, along with E7, is also responsible for the dysregulation of the cell cycle that results in squamous cell dysplasia. The E6 and E7 oncoproteins do this by binding and inhibiting the tumor suppressor genes p53 and RB, respectively. This promotes progression of cells through the cell cycle without appropriate repair of DNA damage, resulting in dysplasia.[4] Due to the ability of HPV to cause cellular dysplasia, koilocytes are found in a number of potentially precancerous lesions.
Lesions containing koilocytes
Koilocytes may be found in potentially precancerous cervical, oral and anal lesions.
Cervical lesions
When examining cytologic specimens, mild koilocytosis is characteristic of ASC-US (atypical squamous cells - undetermined significance). A diagnosis of ASC-US warrants further follow-up to better characterize the extent of the abnormal cells.[5] A more undifferentiated koilocyte, possessing a more hyperchromatic and enlarged nucleus, and a higher degree of cytoplasmic clearing with a discernible peripheral rim favors an interpretation of LSIL (low-grade squamous intraepithelial lesion).[1][2]
Interpretation
These changes occur in the presence of human papillomavirus and occasionally can lead to cervical intraepithelial neoplasia, and if left untreated some may eventually progress to malignant cancer.
References
- ^ a b Nucci MR, Oliva E, eds. (2009). Gynecologic pathology: A volume in the series - Foundations in diagnostic Pathology. Elsevier Churchill Livingstone. ISBN 978-0-443-06920-8.
- ^ a b c DeMay, Richard M. (2007). Practical Principles of Cytopathology Revised. American Society for Clinical Pathology. ISBN 978-0-89189-549-7.
- ^ Shurin, Michael R.; Thanavala, Yasmin; Ismail, Nahed, eds. (2015). "Infection and Cancer: Bi-Directorial Interactions". doi:10.1007/978-3-319-20669-1.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Klatt, Edward C.; Kumar, Vinay (2010), "The Female Genital Tract", Robbins and Cotran Review of Pathology, Elsevier, pp. v, ISBN 978-1-4160-4930-2, retrieved 2020-11-12
- ^ Klatt, Edward (2015). Robbins and Cotran Atlas of Pathology. Print: Saunders.
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