Basal-cell carcinoma
| Basal cell carcinoma | |
|---|---|
 |
|
| Ulcerated basal cell carcinoma affecting the skin of the nose in an elderly individual | |
| Classification and external resources | |
| Specialty | Oncology |
| ICD-10 | C44 (ILDS C44.L21) |
| ICD-9-CM | 173 |
| ICD-O | M8090/3-8093/3 |
| OMIM | 605462 |
| DiseasesDB | 1264 |
| MedlinePlus | 000824 |
| eMedicine | med/214 |
| Patient UK | Basal-cell carcinoma |
| MeSH | D002280 |
Basal cell carcinoma (BCC) (also known as basalioma or basal cell cancer), is the most common skin cancer, and one of the most common cancers in the United States. While BCC has a very low metastatic risk, this tumor can cause significant disfigurement by invading surrounding tissues.
Individuals with a basal-cell carcinoma typically present with a shiny, pearly skin nodule. However, superficial basal-cell cancer can present as a red patch similar to eczema. Infiltrative or morpheaform basal-cell cancers can present as a skin thickening or scar tissue – making diagnosis difficult without using tactile sensation and a skin biopsy. It is often difficult to visually distinguish basal-cell cancer from acne scar, actinic elastosis, and recent cryodestruction inflammation.
Basal-cell carcinoma, nodular type
Basal cell carcinoma in a sun-exposed area
About two thirds of basal-cell carcinomas occur on sun-exposed areas of the body. One-third occur on areas of the body that are not exposed to sunlight, emphasizing the genetic susceptibility of basal-cell cancer.
Basal cell carcinomas are currently considered to have origin from the folliculo-sebaceous-apocrine germ, also known as trichoblast. The differential diagnosis with trichoblastic carcinoma, a rare malignant form of trichoblastoma, can be challenging. Alternatively, one argument is that basal cell carcinoma is trichoblastic carcinoma. Overexposure to sun leads to the formation of thymine dimers, a form of DNA damage. While DNA repair removes most UV-induced damage, not all crosslinks are excised. There is, therefore, cumulative DNA damage leading to mutations. Apart from the mutagenesis, overexposure to sunlight depresses the local immune system, possibly decreasing immune surveillance for new tumor cells.
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