Pityriasis lichenoides chronica L41.1

Author: Prof. Dr. med. Peter Altmeyer

Our authors

Last updated on: 29.10.2020

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guttate parapsoriasis; Parapsoriasis en gouttes; PLC

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Juliusberg, 1899

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Harmless, probably infection-triggered, erythematosquamous, self-limited chronic dermatitis, which is classified as a chronic form of pityriasis lichenoides. The disease can develop de novo or develop further from the acute form of pityriasis lichenoides (et varioliformis) acuta.

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Occurring worldwide, the incidence for the PLC is given as 1: 2,000.

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Unknown, probably dermatitis caused by an infection allergy.

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  • especially in adolescents and young adults, often after infections.
  • m>w.

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Mainly occurring on the trunk, arms, legs (proximal extremities), typically symmetrical and arranged in the cleft lines of the skin.

Clinical features
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Initial 0,3 to 0,6 cm in size, calotte-shaped, red or grey-red, rough, superficially blunt or reflecting papules with or without scales

Alignment along the tension lines of the skin.

In the course of a few weeks the papules fade or turn brown, forming a compact, covering, centrally adhering scaly cover. By gently scratching the surface, the scale cover can be lifted off compactly, but remains mutually adherent(casket lid phenomenon, a typical diagnostic tool for this disease).

Typical is a phase-like course over months; therefore polymorphic picture with different stages of development of the individual florESCENCES.

The disease does not cause any symptoms except for a slight to moderate itching.

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Rather discrete interface dermatitis with low acuteity. In contrast to pityriasis lichenoides acuta, relatively sparse, perivascular and interstitial epidermotropic infiltrate in the upper dermis consisting of lymphocytes and histiocytes. Focal vacuole degeneration at the dermo-epidermal junction with necrotic keratinocytes. Broad parakeratotic keratinization (histological counterpart of clinically detectable wafer scaling).

Direct Immunofluorescence
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Immune complexes in basement membrane zone and vessel walls.

Differential diagnosis
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  • Clinical differential diagnosis:
    • Psoriasis guttata: Mostly acutely occurring 0.1-1.5 cm large, red or pale red papules or plaques with distinct scaling. No alignment of cleavage lines. Often Koebner phenomenon detectable! The Koebner phenomenon can always be triggered and is an important differential diagnostic sign. Ask about psoriatic family burden!
    • Pityriasis rosea: Clinical course with relapsing-like, 1-2 weeks lasting, trunk-related exanthema attacks similar to those of pityriasis rosea. The efflorescences are very typically aligned in cleft lines. Suction. Search for primary medallion! The compact, covering, centrally adherent cover scales of Pityriasis lichenoides chronica are always missing.
    • Varicella: Clinical morphology can be very similar. Different pattern of infection with involvement of the oral mucosa and capillitium. In the PLC vesicles were mostly missing! Pay attention to signs of infection!
    • Lichenoid viral exanthema: Mostly surface smooth efflorescences. Exanthematic course. Clarify signs of infection. Pay attention to AZ!
    • Lichen planus (exanthematicus): Papular, usually rather monomorphic, flexion-sided, extremity accentuated exanthema with surface smooth (the typical lid scale is always missing!) red, firm papules about 0.1-0.5 cm in size which may aggregate to larger plaques. Itching varies in intensity. Typical are striped arrangements of efflorescences in scratch or rub marks (see Köbner phenomenon below). Almost always mucous membrane infestation! Histology is conclusive!
    • Drug exanthema, maculo-papular: The skin symptoms usually appear between the 7th and 12th day after the start of therapy, but also after several weeks or after discontinuation of the drug. Generalized, truncal and extremity exanthema of varying density, usually combined with itching (itching can also be completely absent).
    • Syphilide, papulosquamous: Syphilides are usually accompanied by LK swelling, the appearance rather monomorphic; no itching! Frequent infestation of palms and face. Serology is proving! Histology is groundbreaking (plasmacellular dermatitis).
    • Tuberculide, papulonecrotic: chronicity, evidence of active tuberculosis. Histology is indicative (epithelial cell dermatitis).
  • Histological differential diagnoses:
    • Acute and subacute eczema: spongiosis, extensive parakeratosis, no keratinocyte necrosis. No interface dermatitis in atopic eczema. Possible eosinophilia.
    • Fixed drug reaction: apoptotic keratinocytes, vacuolated junctional zone, satellite necrosis, perivascular lymphocytic infiltrate.
    • Guttate psoriasis: acanthosis, hyper- and parakeratosis with neutrophil inclusions, no keratinocyte necroses; diffuse, also perivascularly compressed lymphocytic infiltrate with neutrophil granulocytes, no erythrocyte extravasations, usually strong epidermotropism.
    • Pityriasis rosea: edema of the papillary body, focal spongiosis, no apoptotic keratinocytes, superficial perivascular lymphocyte infiltrate. No interface dermatitis.
    • Lichen planus: Classical interface dermatitis. Parakeratosis is always absent!
    • Early syphilis: interface dermatitis with psoriasiform epidermal reaction. Dense, band-shaped infiltrate in the upper and middle dermis (lymphocytes, histiocytes and plasma cells; also epitheloid cell component). Plasma cells are absent in the PLC.

General therapy
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An effective therapy is not yet known. A small part of pityriasis lichenoides chronica diseases is of infectious-allergic origin. Therefore, focus search e.g. on chronic tonsillitis or dental granulomas and if necessary, rehabilitation of the foci.

External therapy
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  • Blande care products are indicated, e.g. Eucerinum O/W or W/O, Ash Base Cream, Linola Milk.
  • Alternatively: Tacrolimus, locally and temporarily limited.
  • Good results are also achieved with dermatological climate therapy for chronic forms that persist for years.

Radiation therapy
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If there is no evidence of infection or the antibiotic therapy is unsuccessful, radiation therapy with UV radiation is indicated for adults.

E.g. UVB in the usual dosage, UVB-311 nm (narrowband) or PUVA bath or systemic PUVA therapy.

A UV therapy should be carried out carefully in order not to provoke a relapse!

Internal therapy
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  • In case of itching try with non-sedating antihistamine such as Desloratadine (e.g. Aerius) 1 tbl/day.
  • Oral tetracyclines or cephalosporins.
  • The use of immunosuppressive therapies such as methotrexate 2.5-5.0 mg/week p.o. can only be discussed in severe forms of the disease and in cases of absolute resistance to external therapy approaches and radiation therapy.

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Chronic, week-long to possibly year-long course. Average duration in larger collectives at 20 months (3-132 months). Transition to pityriasis lichenoides et varioliformis acuta possible (rare); tendency to spontaneous regression. In larger groups a transition to T-cell lymphoma of the mycosis fungoides type is observed after 3-11 years in about 5% of cases (Zaaroura H et al. 2017).

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  1. Aydogan K et al (2008) Narrowband UVB (311 nm) phototherapy for pityriasis lichenoides. Photodermatology 24: 128-133
  2. Ersoy-Evans S et al (2007) Pityriasis lichenoides in childhood: a retrospective review of 124 patients. J Am Acad Dermatol 56:205-210
  3. Geller L et al (2015) Pityriasis Lichenoides in Childhood: Review of Clinical Presentation and Treatment Options.pediatric dermatol 32:579-592
  4. Hofmann C et al (1979) Pityriasis lichenoides chronica - a new indication for PUVA therapy? Dermatologica 159: 451-460
  5. Juliusberg F (1899) About pityriasis lichenoides chronica (psoriasiform-lichenoides exanthema) Arch Dermatol Syph 50: 359-374
  6. Klein PA et al (2003) Infectious causes of pityriasis lichenoides: a case of fulminant infectious mononucleosis. J Am Acad Dermatol 49: S151-153
  7. Machan M et al (2012) Pityriasis lichenoides et varioliformis acuta associated with subcutaneous immunoglobulin administration. J Am Acad Dermatol 67:e151-152
  8. Mallipeddi R et al (2003) Refractory pityriasis lichenoides chronica successfully treated with topical tacrolimus. Clin Exp Dermatol 28: 456-458
  9. Markus JR et al (2013) The relevance of recognizing clinical and morphologic features of pityriasis lichenoides: clinicopathological study of 29 cases. Dermatol Pract Concept 31:7-10
  10. Vineyard JM (2003) The clonal nature of pityriasis lichenoides. Arch Dermatol 138: 1063-1067
  11. Zaaroura H et al (2017) Relationship Between Pityriasis Lichenoides and Mycosis Fungoides:
    AClinicopathological, Immunohistochemical, and Molecular Study. Am J Dermatopathol doi: 10.1097/DAD.000000000000001057.


Please ask your physician for a reliable diagnosis. This website is only meant as a reference.


Last updated on: 29.10.2020