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Treating "difficult" skin sites
What are "difficult" sites?
Some areas of the body are difficult to treat because of their anatomical features for example the scalp, face, skin folds, palms, soles, nails and mucous membranes. Moreover, lesions which are visible to others (such as those on the face, hands and scalp) have a profound impact on patient's quality of life, often causing embarrassment and even a feeling of rejection.
Is psoriasis of the scalp chronic?
Psoriasis of the scalp requires long-term treatment. Lesions often become infected. This type of psoriasis is often associated with a fungus or seborrheic dermatitis and is typically characterised by thick scale, which needs to be removed with a keratolytic shampoo containing urea or salicylic acid. After scale has been removed, corticosteroids may be applied, sometimes in combination with a topical vitamin A treatment. Corticosteroids may also be combined with vitamin D derivatives.
In rare cases when repeated scratching is combined with infection, local hair loss may ensue.
How are the skin folds different from other areas?
The levels of moisture (with the resulting tendency for fungal infections to occur) and irritation are frequently significant in the skin folds. These factors exacerbate lesions and prevent them from healing. Skin folds are sometimes known as "flexures", so this type of psoriasis is called "flexural psoriasis". It is also known as "inverse psoriasis". Lesions may be infected by fungus or bacteria, especially in the anal region.
There are several basic rules for treating psoriasis in the skin folds. Patients should dry their skin with a hairdryer after washing and avoid tight clothing or clothing made from synthetic fabrics which increase perspiration. Flexural psoriasis is often treated with corticosteroids or vitamin D derivatives. In cases of severe flares, the dermatologist may prescribe sessions of UVB or B Clear Laser therapy.
Psoriasis of the genital mucous membranes is often associated with lesions in the skin folds (particularly the anus and the natal cleft).
Does facial skin flora make lesions more likely?
It is important to consider the role of pityrosporum (a form of yeast that causes seborrheic dermatitis) in relation to psoriasis and anti-mycotic treatment may be necessary. The best treatment for facial psoriasis remains narrow spectrum UVB therapy, conducted under close medical supervision as certain types of psoriasis may be photo-aggravated.
Maintenance therapy may include corticosteroids or vitamin D derivatives, although the latter are not always well tolerated on the face.
It is also important to keep the skin well moisturised to stop it drying out.
Lesions sometimes occur on the lips, a delicate area that often cracks.
Why are medications poorly absorbed by the skin on the hands and feet?
The skin on the hands and feet has a very thick horny layer in order to withstand friction and pressure. These areas often become cracked. The hands are frequently in contact with irritants, and lesions on the feet are aggravated by friction from shoes and perspiration. The first step in treatment is to remove built-up layers of skin with urea or salicylic vaseline, especially when lesions are very thick or cracked. The second step is to apply corticosteroids with occlusion in the evening, or vitamin D derivatives.
A contact allergy (eczema) sometimes appears on lesions on the hands. You should be careful to re-apply moisturising lotion to the hands and feet frequently. When local treatments are not effective, the dermatologist may sometimes prescribe UVB therapy or oral retinoids.
Why are local treatments for psoriasis of the nail often unsuccessful?
The nail is frequently subject to microtraumas (such as friction and impact) which may trigger a Koebner phenomenon[peodk1] . It is also sometimes vulnerable to candida, a fungal infection. Good results are not generally obtained by local treatments, although vitamin D derivatives can be useful as a long-term therapy. Injection of cortisone into the matrix of the nail is painful. When patients find nail lesions disabling because they are no longer able to grasp objects, or fear social rejection, systemic treatments (such as retinoids and methotrexate) may be prescribed, although account must be taken of their side effects.
Key points
- The first step in treating psoriasis of the scalp is to remove scale with keratolytic shampoos, before applying corticosteroids.
- The most effective treatment for facial psoriasis is narrow spectrum UVB therapy.
UVB or B Clear therapy may be prescribed where there are significant lesions in skin folds.
- In palmoplantar psoriasis, corticosteroids are applied under occlusion.
- In cases where nail lesions have a profound functional and/or psychological impact on the patient, oral therapy may be prescribed.
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