Squamous Cell Carcinoma in Situ

The name 'Squamous cell carcinoma in situ' describes what this whole disease is about. Also called Bowen's Disease (BD), it affects the squamous cells of the skin. These cells are called keratinocytes and they are the outermost cells of the skin. They form the epidermis. It is carcinoma because it represents the very initial stages of skin cancer. 'In situ' means that the disease only affects the local place from which it started. BD usually starts in the epidermis and thus it never spreads to other regions of the skin unless it is left untreated for a long period of time. Keratinocytes grow abnormally within the epidermis and in later stages develop into skin cancer when it spreads to other layers of the skin.

BD usually occurs in adults who are over 30 years old (except in extremely rare situations where it might occur in children) with a higher prevalence rate for people who are over the age of 60. It is predominant in women than men. Of all the occurrences, the prevalence in women is about 70 to 80% with men accounting for the rest. If untreated, BD can develop to squamous cell cancer. This type of cancer only affects the epidermis but it can also spread to other layers of the skin. Approximately 5% of patients of squamous cell carcinoma in situ usually end up with fully spread skin cancer.


The main causes of squamous cell carcinoma in situ are:


Squamous cell carcinoma in situ is usually characterized by abnormal reddish patches on the skin. These patches usually measure 1 to 3 cm in diameter. The parts that have been affected are usually sore and itchy and they might start bleeding when they are scratched. A special type of BD called Bowenoid papulosis usually appears in the groin area as a brown patch.


If a patient is suspected to be suffering from BD, a sample of the skin is usually taken by a dermatologist and tested in the lab. The cells of a person with BD usually appear to be extremely abnormal when looked under the microscope. In fact, whereas other cancerous cells might disguise themselves, BD cells do not.


BD is treatable and most patients stand to have full recovery. There are three main treatment options and they are:

  1. Cryotherapy: it involves spraying very cold liquid nitrogen on the affected areas. The cells will freeze and after some time they will come off.
  2. Photodynamic therapy (PDT): it is a method that combines light and photosensitizing drugs to remove the affected cells from the skin.
  3. Excision surgery: this involves conducting a surgery to cut out the affected cells of the skin

Other treatment options include laser treatment, chemotherapy with 5-fluorouracil, curettage and electrocautery method and topical therapy (also called creams).