POROKERATOSIS OF MIBELLI
- Annular plaque with raised, ridged edge develops from small brownish keratotic papule.
- Atrophic central area.
- May occur anywhere on the body, including mucous membranes. Most common on the limbs, especially hands and feet.
- Usually symptomless, but may be itchy.
- Genetic link with autosomal dominant inheritance.
- Sometimes develops at site of injury, such as on a burn or after radiation.
- Usually first develops in childhood or at puberty. May even occur at birth.
- Rare condition, but more common in men. Occurs only in the fair skinned.
- May slowly increase to reach several centimetres in size.
- Risk of malignant change to basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). Risk is particularly high in the immunosupressed.
- No known cure.
- Appearance may be improved with topical 5-fluorouracil, calcipotriol or imiquimod cream, cryotherapy, laser or topical or oral retinoid.
- In view of risk of malignancy, advise regular monitoring and reporting of any change in the lesion. If in doubt, perform a biopsy and treat accordingly.
- Sun protection is very important to prevent development of skin cancer.
- In situ SCC.
- Follows long-term exposure to UV or X-ray radiation, arsenic or HPV type 16.
- More common in the fair skinned.
- Good prognosis. Only 5 per cent progress to invasive SCC.
- Erythematous, scaly plaque which gradually increases in size.
- Unresponsive to topical steroids.
- Usually on sun-exposed areas, especially head, neck or limbs.
- Biopsy to confirm diagnosis.
- Check the rest of the body for lesions.
- Cryotherapy, curettage and cautery - although these methods do not allow for confirmation of complete lesion removal.
- Topical 5-fluorouracil or imiquimod.
- Radiotherapy may be advised for those in poor health or with multiple lesions.
- Photodynamic therapy is sometimes recommended.
- Surgical excision and histological check.