Basal cell carcinoma pathophysiology: Difference between revisions
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! Subtypes of BCC | ! rowspan="2" | Subtypes of BCC | ||
! Gross | ! colspan="2" | Gross features | ||
! colspan="2" | Microscopic features | |||
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!Findings | |||
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*Mostly seen on the head and neck | *Mostly seen on the head and neck | ||
[[File:BCC Nodular type.jpg|100px|none]] | [[File:BCC Nodular type.jpg|100px|none]] | ||
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*Discrete nests of malignant basaloid cells in the dermis | *Discrete nests of malignant basaloid cells in the dermis | ||
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*Mucoid stroma containing plump spindle cells | *Mucoid stroma containing plump spindle cells | ||
[[File:Basal cell carcinoma histopathology (3).jpg|200px|none]] | [[File:Basal cell carcinoma histopathology (3).jpg|200px|none]] | ||
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*Most common on the trunk | *Most common on the trunk | ||
[[File:Basal cell carcinoma, superficial.jpg|200px|none]] | [[File:Basal cell carcinoma, superficial.jpg|200px|none]] | ||
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*Multiple lobular foci of basaloid palisading keratinocyte tumors | *Multiple lobular foci of basaloid palisading keratinocyte tumors | ||
*These are usually attached superficially to the epidermis with a myxoid stroma and band-like lichenoid infiltrate | *These are usually attached superficially to the epidermis with a myxoid stroma and band-like lichenoid infiltrate | ||
[[File:Basal cell carcinoma histopathology (2).jpg|200px|none]] | [[File:Basal cell carcinoma histopathology (2).jpg|200px|none]] | ||
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*Well-circumscribed pearly papule | *Well-circumscribed pearly papule | ||
*Most common on the head and neck region | *Most common on the head and neck region | ||
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*Well-circumscribed | *Well-circumscribed | ||
*Anastomosing strands of basaloid cells and scattered infundibulum-like cystic structures | *Anastomosing strands of basaloid cells and scattered infundibulum-like cystic structures | ||
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*Sessile plaque/pedunculated papulonodule | *Sessile plaque/pedunculated papulonodule | ||
*They have a predilection for trunk region | *They have a predilection for trunk region | ||
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*Multiple collections of delicate strands of epidermal basaloid keratinocytes | *Multiple collections of delicate strands of epidermal basaloid keratinocytes | ||
*These are usually arranged in a reticular pattern within a spindle cell stroma | *These are usually arranged in a reticular pattern within a spindle cell stroma | ||
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*Most common on head and neck region | *Most common on head and neck region | ||
[[File:PMC3339125 JCAS-5-3-g004.png|100px|none]] | [[File:PMC3339125 JCAS-5-3-g004.png|100px|none]] | ||
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*Thin cords of basaloid cells surrounded by a sclerotic collagenous stroma | *Thin cords of basaloid cells surrounded by a sclerotic collagenous stroma | ||
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*Positive staining of tumor stroma with smooth muscle alpha-actin | *Positive staining of tumor stroma with smooth muscle alpha-actin | ||
[[File:PMC4513413 IDOJ-6-286-g002.png|200px|none]] | [[File:PMC4513413 IDOJ-6-286-g002.png|200px|none]] | ||
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*They may have overlying crusts, erosions, ulcerations, or papules | *They may have overlying crusts, erosions, ulcerations, or papules | ||
[[File:Basal cell carcinoma (1).jpg|200px|none]] | [[File:Basal cell carcinoma (1).jpg|200px|none]] | ||
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*Thin cords with angulated ends of few basaloid keratinocytes | *Thin cords with angulated ends of few basaloid keratinocytes | ||
*Usually embedded in a classic mucinous/myxoid stroma | *Usually embedded in a classic mucinous/myxoid stroma | ||
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*Erythematous macule or thin papule/plaque | *Erythematous macule or thin papule/plaque | ||
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*Multiple small aggregates of basaloid cells within the dermis, with subtle peripheral palisading and retraction artifact | *Multiple small aggregates of basaloid cells within the dermis, with subtle peripheral palisading and retraction artifact | ||
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*Majority found on the head and neck | *Majority found on the head and neck | ||
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*Well-defined nodular or superficial BCC component overlying an invasive front showing basal cell carcinoma and squamous cell carcinoma histologic feature | *Well-defined nodular or superficial BCC component overlying an invasive front showing basal cell carcinoma and squamous cell carcinoma histologic feature | ||
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Revision as of 16:39, 14 February 2019
Basal cell carcinoma Microchapters |
Diagnosis |
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Case Studies |
Basal cell carcinoma pathophysiology On the Web |
American Roentgen Ray Society Images of Basal cell carcinoma pathophysiology |
Risk calculators and risk factors for Basal cell carcinoma pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Shivali Marketkar, M.B.B.S. [2]
Overview
Basal cell carcinomas develop in the basal cell layer of the skin. Cumulative DNA damage caused by chronic sunlight exposure results in DNA mutations that predispose to the development of basal cell carcinoma. On gross pathology, basal cell carcinoma lesions may demonstrate pearly pink nodules with telangiectasias, rolled borders, and central crusting with or without an ulcerating lesion (rodent ulcer). On microscopic analysis, peripheral palisading nuclei are characteristic.
Pathophysiology
Genetics
- A number of aberrations involving the sonic hedgehog signaling pathway(SHH) are noted[1][2][3]
- This pathway is vital for the regulation of cell growth, and differentiation and loss of inhibition of this pathway is associated with development of basal cell cancer
- The majority of mutations in sporadic basal cell carcinoma and basal cell nevus syndrome(BCNS) patients occur in PTCH1 gene(a protein that inhibits Smoothened gene(SMO))
- The second most common mutation in sporadic basal cell carcinoma and basal cell nevus syndrome(BCNS) patients are gain-of-function mutations of the Smoothened gene(SMO)
- Loss of PTCH1 results in the failure of Smoothened inhibition, subsecuently leading to increases in GLI1 levels, changes in transcription, and subsequent tumorigenesis
- Gain-of-function Smoothened(SMO) mutations also leads to increased GLI1 levels and tumorigenesis
Loss of PTCH1 | Gain of function SMO | ||||||||||||||||||||||||
Lack of SMO inhibition | Activation of SMO-GLI signaling | ||||||||||||||||||||||||
↑GLI1 levels | |||||||||||||||||||||||||
Changes in transcription | |||||||||||||||||||||||||
Tumorigenesis | |||||||||||||||||||||||||
Enviromental Exposure
- Basal cell carcinomas develop in the basal cell layer of the skin
- Cumulative DNA damage caused by chronic sunlight exposure results in DNA mutations that predispose to the development of basal cell carcinoma
- While DNA repair eliminates most UV-induced damage, not all cross-links are excised, which eventually results in mutations
- Apart from the mutagenesis, sunlight depresses the local immune system, possibly decreasing immune surveillance for new tumor cells
Pathology
Basal cell carcinoma pathological features mainly depend upon the subtype. The following table summarizes them:[4][5]
Subtypes of BCC | Gross features | Microscopic features | ||
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Findings | Images | Findings | Images | |
Nodular |
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Superficial |
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Infundibulocystic |
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Fibroepithelial |
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Morpheaform |
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Infiltrative |
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Micronodular |
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Basosquamous |
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Video
{{#ev:youtube|JnJXrFnvOKs}}
References
- ↑ Mohan SV, Chang AL (2014). "Advanced Basal Cell Carcinoma: Epidemiology and Therapeutic Innovations". Curr Dermatol Rep. 3: 40–45. doi:10.1007/s13671-014-0069-y. PMC 3931971. PMID 24587976.
- ↑ Pellegrini C, Maturo MG, Di Nardo L, Ciciarelli V, Gutiérrez García-Rodrigo C, Fargnoli MC (November 2017). "Understanding the Molecular Genetics of Basal Cell Carcinoma". Int J Mol Sci. 18 (11). doi:10.3390/ijms18112485. PMC 5713451. PMID 29165358.
- ↑ Yunoki T, Tabuchi Y, Hirano T, Miwa S, Imura J, Hayashi A (November 2018). "Gene networks in basal cell carcinoma of the eyelid, analyzed using gene expression profiling". Oncol Lett. 16 (5): 6729–6734. doi:10.3892/ol.2018.9484. PMC 6202553. PMID 30405815.
- ↑ Cameron, Michael C.; Lee, Erica; Hibler, Brian P.; Barker, Christopher A.; Mori, Shoko; Cordova, Miguel; Nehal, Kishwer S.; Rossi, Anthony M. (2019). "Basal cell carcinoma". Journal of the American Academy of Dermatology. 80 (2): 303–317. doi:10.1016/j.jaad.2018.03.060. ISSN 0190-9622.
- ↑ Sehgal VN, Chatterjee K, Pandhi D, Khurana A (2014). "Basal cell carcinoma: pathophysiology". Skinmed. 12 (3): 176–81. PMID 25134314.