Published on 18/03/2015 by admin
Filed under Dermatology
Last modified 18/03/2015
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Alex Milligan and Graham A. Johnston
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Pityriasis lichenoides chronica (PLC) typically consists of small erythematous papules, which may be purpuric. These develop a characteristic shiny mica-like scale attached to the center. They occur predominantly over the trunk and proximal limbs. As the name implies, PLC may persist for many years, though spontaneous resolution does occur. Patients should be warned that relapse is common and that recurrent courses of therapy may be required.
Anecdotally, PLC is said to run a more benign, self-limiting course in children, but more recently it has been shown that in children it is more likely to run an unremitting course, with greater lesional distribution, more dyspigmentation, and a poorer response to treatment. Some authors argue that there is an overlap with cutaneous lymphoma.
Crowson AN, Morrison C, Li J. Hum Pathol 2007; 38: 479–90.
A prospective study of 46 patients concluded that PLC is an indolent cutaneous T-cell dyscrasia with a limited propensity for progression to mycosis fungoides.
There are no controlled therapeutic trials for this condition, and case series are only small. In many therapeutic trials PLC has been grouped together with pityriasis lichenoides et varioliformis acuta (PLEVA) and management strategies are therefore often similar or interchangeable.
Topical corticosteroids are only reported as effective anecdotally in textbooks rather than in studies. They are often used with antihistamines to reduce pruritus, but they are not reported to affect the course of the disease.
The majority of reports describe benefits with UV therapy, and therefore either UV alone or with psoralen plus UVA (PUVA) therapy is recommended for all patients. The response appears to be unpredictable, however, and the total dose required is extremely variable.
Antibiotics appear to be more helpful in children, sometimes used in combination therapy.
For severe or refractory cases methotrexate, cyclosporine, and acitretin have all been described as effective in small numbers of patients.
For most treatment modalities, patients who have been described as improved have usually had fewer new lesions developing, a shortened disease course, and a greater time to relapse than untreated patients.
Consider skin biopsy
Although a skin biopsy is usually unnecessary in clinically obvious cases, it may be useful before commencing aggressive systemic therapy.
An infective etiology is often suggested, but no pathogen has yet been implicated, though an association with toxoplasmosis has been described. These reports tend to come from endemic areas, and so investigation for a triggering infection is unnecessary in cases without evidence of specific infection.
Nassef NE, Hamman MA. J Egypt Soc Parasitol 1997; 27: 93–9.
Twenty-two patients with PLC and 20 healthy controls were examined clinically and serologically for toxoplasmosis. Three (15%) of the controls had toxoplasmosis, compared to eight (36%) of the patients with PLC. Five of the latter had subsidence of skin lesions after pyrimethamine and sulfapyrimidine treatment.
Viral infection has been found in association.
Kim JE, Yun WJ, Mun SK, Yoon GS, Huh J,Choi JH, Chang S. J Cutan Pathol 2011; 38: 649–56.
Fifty-one patients with pityriasis lichenoides (not subdivided into PLEVA and PLC) were analyzed. Human herpes virus-8 (HHV-8) was found in 11 (21%) of affected patients but in none of the 25 controls.
Treatment of Skin Disease Comprehensive Therapeutic Strategies 4e
UVB
Combined UVA and UVB
PUVA
