Disseminated Superficial Actinic Porokeratosis (DSAP) is a kind of skin spot, which is inherited. It is a sub-division of porokeratosis, a 'cutaneous disorder of keratinization'. It develops on the skin when it highly exposed to the harmful rays of the sun.
The spot on the skin begin as a bump, which is a combination of red and brown color. Gradually the bump enlarges and turns lighter in the center with a darker rim. Usually, the lower legs and arms of a body are affected by this lesion, which is scaly in nature. It creates dry patches on the affected region.
The skin lesion of DSAP commences as a 1 to 3 millimeter 'conical papule', which is either brown or brownish red in color. It usually appears around a hair follicle that contains a 'keratotic' or scaly plug.
Gradually, it enlarges and a slightly elevated, sharp, keratotic ring develops that expand to a diameter of about 10 mm and sometimes even more than this. The skin inside the ring gets slightly red or brown in color and becomes thinner; however, a 'pale ring' can be noticed surrounded by the ridge. Sometimes, even the ridge turns into the color of dark brown.
There is no sweating within the lesions. However, because of exposure to the sun, patients may feel itching around the affected area. In hotter regions, a large number of people may be affected by skin lesions, which alter from a 'circular to a polycyclic outline (overlapping circles)'. However, in cooler climates, there are a few patients suffering from skin lesions.
Disseminated Superficial Actinic Porokeratosis mostly affects the lower legs and arms and women are more likely to develop lesion than their male counterparts. DSAP very rarely affects the cheeks and forehead. In fact, there are no cases with DSAP occurring on the palms, scalp, or soles.
It is uncommon that DSAP develops into a skin cancer. However, numerous patients with DSAP may also contract 'solar keratoses' and other forms of skin cancer, if they continuously expose themselves to the sun and do not take any precautionary measures.
Causes of Disseminated Superficial Actinic Porokeratosis
Any kind of Porokeratosis can occur due to ultraviolet light exposure, genetic inheritance and immunosuppression. A person may develop DSAP due to the following reasons:
- Excessive sun exposure or exposure to artificial ultraviolet radiation in a patient can cause DSAP.
- A person can also report exacerbations if he remain in the sunlight for prolonged time, or continuously repeats exposure on tanning bed. Even therapeutic phototherapy or photo chemotherapy for psoriasis and electron beam radiation therapy may cause exacerbations.
- Immunosuppression influence nonactinic DSP and DSAP in patients. Due to this, a viral etiology has also been assumed.
Physical Appearance of Disseminated Superficial Actinic Porokeratosis
- You will notice several indistinct, small, light brown patches with a narrow border on the extensor (skeletal muscle) surfaces of the legs and arms.
- If examined under Dermoscopy, it will show a 'white track' like structure on the edge of the lesion. A brownish pigmentation will also be noticed on the inner side with a 'double white track' in some other parts of the lesion. This match to the 'cornoid lamella'. The core may reveal a white homogeneous area, which is parallel to acanthotic epithelium, or globules, red dots, and lines equivalent to enlarged capillary vessels. [Dermoscopy is a non-invasive or non-puncturing process that enables evaluation of microstructures and colors of the dermoepidermal junction, the epidermis, and the papillary dermis in the living organisms, which is otherwise, cannot be seen by the naked eye.
- You can find in about 15 percent patients facial lesions.
- Nonactinic DSP generally has comprehensive distribution, leaving the soles and the palms.
Treatment of Disseminated Superficial Actinic Porokeratosis
Various methods have been developed over the years for the treatment of Disseminated Superficial Actinic Porokeratosis or DSAP. These methods are:
- Cryotherapy: this method involves treating the skin surface lesion by freezing it. Several 'cryogens' are used for this process. These include Liquid nitrogen, which is the most widespread method used by doctors; and Carbon dioxide snow, which was commonly used around 20 years back.
- 5-Fluorouracil cream: Popularly known as 5-FU, this cream is advised by doctors for Actinic Keratosis and squamous cell carcinoma. Its application destroys cells that are damaged by UV rays of the sun. It enables the skin to regain its youth and makes it smooth. It can be applied on scalp and face.
- Tretinoin cream: It is a topical retinoid cream which should only be used after your dermatologist or doctor has prescribed it.
- Photodynamic therapy: It is a newer kind of therapy used by dermatologists for various skin cancers.
Some other treatments include Alpha hydroxy acid cream, Calcipotriol ointment and Oral acitretin.