Parapsoriasis

Parapsoriasis is also known as ‘chronic superficial scaly dermatitis’, or ‘digitate dermatosis’. It is an uncommon chronic skin condition characterised by round or oval red, slightly scaly patches on limbs and trunk. Parapsoriasis mostly affects adults especially men. The cause is unknown.

Clinical Features

Parapsoriasis begins insidiously with one or more red, slightly scaly patches. The commonest site is on the lower limbs, but the trunk and upper limbs are often affected. It is seldom seen on the face, palms or soles.

The patches are generally round or oval, but finger-like processes are also common especially on the abdomen, and this accounts for the alternative name digitate or finger-like dermatosis. The patches are usually about 2.5 cm across, although much larger areas form at times, especially on the lower limbs. The colour is pink, brown or slightly yellow. The individual patches are often slightly wrinkled and appear like cigarette paper.

Symptoms are usually minimal, but some itching may occur. The patches are more prominent in winter than in summer. If they clear with treatment, they tend to recur in the same, or adjacent, areas when it is stopped.

After extending for a time most cases then remain static and with minor fluctuations persist throughout life. In a few patients the condition clears permanently.

Investigations

A skin biopsy is usually necessary to distinguish parapsoriasis from other skin conditions, particularly cutaneous T-cell lymphoma. Under the microscope parapsoriasis resembles mild eczema.

Follow up

Although parapsoriasis is thought to be completely benign, occasionally patches originally diagnosed as parapsoriasis prove later to be cutaneous T-cell lymphoma. It is important to see your dermatologist if any change develops in the patches. This might be a change in colour, thickening, increased scaling, and crusting or skin thinning.

Treatment

Not all patients need treatment, as parapsoriasis is harmless but unfortunately difficult to clear up. The following may be useful:

Simple emollients to relieve dryness and scaling
Topical steroids to reduce itching
Phototherapy can clear the patches at least temporarily.

Follow-up and contact details

You will be offered follow up in the long term in the CTCL clinic in Newcastle upon Tyne. If you are concerned or your condition changes between appointments then please contact us for an earlier appointment by contacting the consultant dermatology secretaries on 0191 2824340 or specialist nurse team on 0191 2824110.