Porokeratosis of Mibelliis a skin condition that usually develops in children or young adults. It begins as one or a few small, brownish bumps that grow into raised, bumpy patches. These patches slowly increase in size over time. The cause of this condition is unknown, though exposure to sunlight or other forms of radiation, genetic factors and a weakened immune system have been suggested as possible risk factors. Porokeratosis of Mibelli may sometimes harm normal tissue underlying the affected area; it may also develop into skin cancer. Treatment depends on the size, location, and aggressiveness of porokeratosis in each affected individual; it may include observation only, medication, or surgery.

Porokeratosis of Mibelli may develop in one or more locations on the skin, but it is not thought to spread from one part of the body to another.

Porokeratosis of Mibelli is not an infectious condition; it cannot be passed from one person to another the way a cold virus could. However, there may be a genetic factor that increases the chance of developing this disease (genetic predisposition) which could be passed from parent to child. A genetic risk factor for porokeratosis of Mibelli is suspected because there have been reports of multiple affected relatives in the same family.

Porokeratosis of Mibelli can give rise skin cancer. One article showed that porokeratosis of Mibelli progressed to skin cancer in approximately 8% of affected individuals. The chance of porokeratosis becoming cancerous is increased if the affected area is large, located on the limbs, or has been present for a long time.

Treatment depends on the size, location, and aggressiveness of porokeratosis of Mibelli. Affected individuals are recommended to visit their personal physician regularly to watch for signs of skin cancer, limit sun exposure to the affected area, and use moisturizers as needed. Imiquimod cream has been found to be an effective treatment, as has 5-fluorouracil cream. A group of medications called retinoids (including acitretin and isotretinoin), as a pill or cream, may be another treatment option. If a skin cancer develops from porokeratosis of Mibelli, surgery is recommended.

Typically, if porokeratosis of Mibelli is not treated, it will continue to increase in size slowly. In some adults, porokeratosis of Mibelli can arise and grow rapidly. There is a small chance that porokeratosis could give rise to a skin cancer.