Pityriasis rubra pilaris manifests in various ways. Patients may have plaques that are erythematous, scaly, or follicular. Sometimes, it may manifest as erythroderma with an “island of sparing,” which is normal-looking skin in the affected areas.
How to make the diagnosis
Psoriasis can be diagnosed by physical examination. A skin biopsy is not usually necessary but can be helpful for complex cases.
There are no laboratory or genetic tests to confirm the diagnosis of psoriasis. Depending on the case, routine bloodwork (eg, complete blood count and metabolic panel) and infectious disease tests (eg, HIV, hepatitis panel, and rapid plasma reagin for syphilis) can be helpful to rule out other etiologies of skin rash.
Treatment is based on patient factors and disease severity
Starting with a low- to medium-potency steroid, such as betamethasone valerate 0.1% cream twice per day or triamcinolone acetonide 0.1% cream twice per day for 2 weeks, provides high safety and efficacy for localized disease.9 An appropriate-potency steroid should be chosen based on the disease severity, location, and patient’s preference and age. Topical vitamin D analogues often are used in conjunction with topical steroids to treat psoriasis.9
Depending on the severity, patient age, comorbidities, and availability of treatment, other treatment options for psoriasis include oral methotrexate (2.5 mg to 25 mg weekly, starting with a low dose), acitretin (10 mg to 50 mg daily), apremilast (10 mg daily, gradually increasing to 30 mg twice per day in a divided dose), biologics, and narrowband ultraviolet light.
In this case, betamethasone dipropionate 0.05% cream twice daily for 2 weeks was not sufficiently effective due to the extent of the psoriasis. Following consultation with a dermatologist, clobetasol propionate 0.05% cream twice per day and oral apremilast (10 mg once per day on the first day and 10 mg twice per day afterward) were prescribed for 2 weeks. The patient’s psoriasis improved somewhat after 2 weeks of the treatment, but many plaques remained. Therefore, apremilast was stopped and subcutaneous adalimumab was started (initial loading dose, 80 mg, then 40 mg every other week). The psoriasis lesions cleared over the next 2 to 3 months. The patient was maintained on the adalimumab to avoid a recurrence of lesions.