Squamous cell carcinoma of the skin pathophysiology: Difference between revisions

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*<nowiki/>One cri<nowiki/>tical pathogenic event is the development of apoptotic resistance through functional loss of TP53, a well<nowiki/>-studied tumor<nowiki/> suppressor gene.  
*<nowiki/>One cri<nowiki/>tical pathogenic event is the development of apoptotic resistance through functional loss of TP53, a well<nowiki/>-studied tumor<nowiki/> suppressor gene.  
**<nowiki/>TP53 mutations are seen in over 90% of skin cancers diagnosed in the United States, as well as in most precursor<nowiki/> skin lesions,<nowiki/> suggesting that loss of TP53 is an early event in the development of cSCC.<ref name="pmid16712710">{{cite journal| author=Brash DE| title=Roles of the transcription factor p53 in keratinocyte carcinomas. | journal=Br J Dermatol | year= 2006 | volume= 154 Suppl 1 | issue=  | pages= 8-10 | pmid=16712710 | doi=10.1111/j.1365-2133.2006.07230.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16712710  }}</ref>
**<nowiki/>TP53 mutations are seen in over 90% of skin cancers diagnosed in the United States, as well as in most precursor<nowiki/> skin lesions,<nowiki/> suggesting that loss of TP53 is an early event in the development of cSCC.<ref name="pmid16712710">{{cite journal| author=Brash DE| title=Roles of the transcription factor p53 in keratinocyte carcinomas. | journal=Br J Dermatol | year= 2006 | volume= 154 Suppl 1 | issue=  | pages= 8-10 | pmid=16712710 | doi=10.1111/j.1365-2133.2006.07230.x | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16712710  }}</ref>
* UVR causes deoxyribonucleic acid (DNA) damage through the creation of pyrimidine dimers, a process known to result in the genetic mutation of ''TP53.''  
* UVR causes [[deoxyribonucleic acid]] ([[DNA]]) damage through the creation of [[pyrimidine]] dimers, a process known to result in the genetic mutation of ''TP53.''
* Upon subsequent UVR exposure, keratinocytes undergo clonal expansion, acquiring further genetic defects, ultimately leading to invasive cutaneous squamous cell carcinoma.
* Upon subsequent UVR exposure, keratinocytes undergo clonal expansion, acquiring further genetic defects, ultimately leading to invasive cutaneous squamous cell carcinoma.
* Many other genetic abnormalities are believed to contribute to the pathogenesis of squamous cell carcinoma of the skin, including mutations of ''BCL2'' and ''RAS.''  
* Many other genetic abnormalities are believed to contribute to the pathogenesis of squamous cell carcinoma of the skin, including mutations of ''BCL2'' and ''RAS.''  
* Likewise, alterations in intracellular signal transduction pathways, including the epidermal growth factor receptor (EGFR) and cyclo-oxygenase (COX), have been shown to play a role in the development of squamous cell carcinoma of the skin.
* Likewise, alterations in intracellular signal transduction pathways, including the [[epidermal growth factor receptor]] (EGFR) and [[cyclooxygenase]] ([[COX]]), have been shown to play a role in the development of squamous cell carcinoma of the skin.
* Squamous cell carcinoma in situ (CIS), sometimes referred to as Bowen disease, is a precursor to invasive cSCC. Characteristics of this lesion include nuclear atypia, frequent mitoses, cellular pleomorphism, and dyskeratosis, parakeratosis, and hyperkeratosis.
* Squamous cell [[carcinoma in situ]] (CIS), sometimes referred to as Bowen disease, is a precursor to invasive cSCC. Characteristics of this lesion include nuclear atypia, frequent mitoses, cellular pleomorphism, and dyskeratosis, parakeratosis, and hyperkeratosis.
*<nowiki/>[[p53]] is mutated commonly in [[Actinic keratosis]], demonstrating that [[Dysplastic change|dysplastic]] lesions have acquired the initial [[Genetic mutations|ge]]<nowiki/>[[Genetic mutations|netic mutation]]<nowiki/>s prior to becoming [[cutaneous squamous cell carcinoma]].<ref name="pmid11966728">{{cite journal |vauthors=Ortonne JP |title=From actinic keratosis to squamous cell carcinoma |journal=Br. J. Dermatol. |volume=146 Suppl 61 |issue= |pages=20–3 |date=April 2002 |pmid=11966728 |doi= |url=}}</ref><ref name="pmid15976832">{{cite journal |vauthors=Berner A |title=[Actinic keratosis and development of cutaneous squamous cell carcinoma] |language=Norwegian |journal=Tidsskr. Nor. Laegeforen. |volume=125 |issue=12 |pages=1653–4 |date=June 2005 |pmid=15976832 |doi= |url=}}</ref><ref name="pmid15468170">{{cite journal |vauthors=Tsai KY, Tsao H |title=The genetics of skin cancer |journal=Am J Med Genet C Semin Med Genet |volume=131C |issue=1 |pages=82–92 |date=November 2004 |pmid=15468170 |doi=10.1002/ajmg.c.30037 |url=}}</ref>
*<nowiki/>[[p53]] is mutated commonly in [[Actinic keratosis]], demonstrating that [[Dysplastic change|dysplastic]] lesions have acquired the initial [[Genetic mutations|ge]]<nowiki/>[[Genetic mutations|netic mutation]]<nowiki/>s prior to becoming [[cutaneous squamous cell carcinoma]].<ref name="pmid11966728">{{cite journal |vauthors=Ortonne JP |title=From actinic keratosis to squamous cell carcinoma |journal=Br. J. Dermatol. |volume=146 Suppl 61 |issue= |pages=20–3 |date=April 2002 |pmid=11966728 |doi= |url=}}</ref><ref name="pmid15976832">{{cite journal |vauthors=Berner A |title=[Actinic keratosis and development of cutaneous squamous cell carcinoma] |language=Norwegian |journal=Tidsskr. Nor. Laegeforen. |volume=125 |issue=12 |pages=1653–4 |date=June 2005 |pmid=15976832 |doi= |url=}}</ref><ref name="pmid15468170">{{cite journal |vauthors=Tsai KY, Tsao H |title=The genetics of skin cancer |journal=Am J Med Genet C Semin Med Genet |volume=131C |issue=1 |pages=82–92 |date=November 2004 |pmid=15468170 |doi=10.1002/ajmg.c.30037 |url=}}</ref>
* The mechanism leading to genomic instability in [[keratinocytes]] likely results from [[UVB radiation|UVB-induced]] inactivation of [[P53 gene|p5]]<nowiki/>[[P53 gene|3]], since approximately 58% of [[cutaneous squamous cell carcinoma]] harbor [[UVB]] signature [[mutations]] such as CC→TT and C→T transitions.<ref name="pmid52880">{{cite journal |vauthors=Borelli D, Salas J |title=[The use of trypan blue instead of cotton blue in mycology] |language=Spanish; Castilian |journal=Rev. Latinoam. Microbiol. |volume=17 |issue=3 |pages=185–6 |date=1975 |pmid=52880 |doi= |url=}}</ref>
* The mechanism leading to genomic instability in [[keratinocytes]] likely results from [[UVB radiation|UVB-induced]] inactivation of [[P53 gene|p5]]<nowiki/>[[P53 gene|3]], since approximately 58% of [[cutaneous squamous cell carcinoma]] harbor [[UVB]] signature [[mutations]] such as CC→TT and C→T transitions.<ref name="pmid52880">{{cite journal |vauthors=Borelli D, Salas J |title=[The use of trypan blue instead of cotton blue in mycology] |language=Spanish; Castilian |journal=Rev. Latinoam. Microbiol. |volume=17 |issue=3 |pages=185–6 |date=1975 |pmid=52880 |doi= |url=}}</ref>
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Although poorly differentiated [[tumors]] tend to behave more aggressively, well-differentiated [[tumors]] can also give rise to [[metastasis]] and result in death. Several [[histological]] variants of [[squamous cell carcinoma]] have been documented, including [[Verrucous carcinoma|verrucous]], [[Spindle cells|spindle cell]] and [[pseudovascular]].
Although poorly differentiated [[tumors]] tend to behave more aggressively, well-differentiated [[tumors]] can also give rise to [[metastasis]] and result in death. Several [[histological]] variants of [[squamous cell carcinoma]] have been documented, including [[Verrucous carcinoma|verrucous]], [[Spindle cells|spindle cell]] and [[pseudovascular]].
 
== Microscopic Pathology ==
=== Microscopic Pathology ===
*  
*  
* Large [[lesions]] require a thorough sample that will adequately assess the entirety of the [[Lesions|lesion]].  
* Large [[lesions]] require a thorough sample that will adequately assess the entirety of the [[Lesions|lesion]].  
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**Moderately differentiated: Has an appearance that is midway between poorly [[differentiated]] and well [[differentiated]].
**Moderately differentiated: Has an appearance that is midway between poorly [[differentiated]] and well [[differentiated]].
**[[Squamous cell carcinoma in situ of skin|Squamous cell carcinoma in situ]] - has full thick atypia of [[Squamous cell|squamous cells]] (including surfaces) without [[invasion]] through the [[basement membrane]].
**[[Squamous cell carcinoma in situ of skin|Squamous cell carcinoma in situ]] - has full thick atypia of [[Squamous cell|squamous cells]] (including surfaces) without [[invasion]] through the [[basement membrane]].


==References==
==References==

Latest revision as of 14:15, 14 August 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aditya Govindavarjhulla, M.B.B.S. [2], Raviteja Guddeti, M.B.B.S. [3]

Overview

Squamous cell carcinoma (SCC) is type of non-melanoma skin cancer. The cancer arises as a result of uncontrolled growth of the squamous cells in the epidermis of the skin. Unlike it's counter part, the basal cell carcinoma which also belongs to the group of non-melanoma cancer, squamous cell carcinoma is rapid growing and invasive. SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun, such as the rim of the ear, lower lip, face, bald scalp, neck, hands, arms and legs. Wrinkling, changes in pigmentation, and loss of elasticity of the skin are often the telltale signs of sun damage.

Pathophysiology

Squamous cell carcinoma is a potentially invasive cancer that arises from the surface epithelium.The development of squamous cell carcinoma is frequently a multistep process. Early lesions tend to be either actinic keratoses, with atypia of the basal keratinocytic layer of the epidermis or squamous cell carcinoma in situ, in which keratinocytic atypia spans the full thickness epidermis.

These precursors are frequently present adjacent to invasive squamous cell carcinomas which invade the dermis as nests, islands, or cords squamous cells with or occasionally as individual cells. Several grading schemes have been developed for squamous cell carcinoma and incorporate the extent of keratinization (a form of differentiation) and nuclear atypia. A widely used scheme divides tumors into well, moderately, or poorly differentiated.

Although poorly differentiated tumors tend to behave more aggressively, well-differentiated tumors can also give rise to metastasis and result in death. Several histological variants of squamous cell carcinoma have been documented, including verrucous, spindle cell and pseudovascular.

Microscopic Pathology

References

  1. Brash DE (2006). "Roles of the transcription factor p53 in keratinocyte carcinomas". Br J Dermatol. 154 Suppl 1: 8–10. doi:10.1111/j.1365-2133.2006.07230.x. PMID 16712710.
  2. Ortonne JP (April 2002). "From actinic keratosis to squamous cell carcinoma". Br. J. Dermatol. 146 Suppl 61: 20–3. PMID 11966728.
  3. Berner A (June 2005). "[Actinic keratosis and development of cutaneous squamous cell carcinoma]". Tidsskr. Nor. Laegeforen. (in Norwegian). 125 (12): 1653–4. PMID 15976832.
  4. Tsai KY, Tsao H (November 2004). "The genetics of skin cancer". Am J Med Genet C Semin Med Genet. 131C (1): 82–92. doi:10.1002/ajmg.c.30037. PMID 15468170.
  5. Borelli D, Salas J (1975). "[The use of trypan blue instead of cotton blue in mycology]". Rev. Latinoam. Microbiol. (in Spanish; Castilian). 17 (3): 185–6. PMID 52880.
  6. Strabala TJ, Bednarek SY, Bertoni G, Amasino RM (April 1989). "Isolation and characterization of an ipt gene from the Ti plasmid Bo542". Mol. Gen. Genet. 216 (2–3): 388–94. PMID 2747621.
  7. Spencer JM, Kahn SM, Jiang W, DeLeo VA, Weinstein IB (July 1995). "Activated ras genes occur in human actinic keratoses, premalignant precursors to squamous cell carcinomas". Arch Dermatol. 131 (7): 796–800. PMID 7611795.
  8. Khavari PA (April 2006). "Modelling cancer in human skin tissue". Nat. Rev. Cancer. 6 (4): 270–80. doi:10.1038/nrc1838. PMID 16541145.


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