DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages

Translate

Pityriasis lichenoides

Authors: Vanessa Ngan, Staff Writer, 1998. Updated: Dr Nisal Punchihewa, Junior Medical Officer, Monash Medical Centre, Melbourne, Victoria, Australia; Dr Martin Keefe, Dermatologist and Assistant Editor. Copy edited by Gus Mitchell. February 2022


Pityriasis lichenoides — codes and concepts
open

What is pityriasis lichenoides?

Pityriasis lichenoides (PL) is an uncommon cutaneous rash of uncertain aetiology.  The acute form, pityriasis lichenoides et varioliformis acuta (PLEVA), and the chronic form, pityriasis lichenoides chronica (PLC), sit at either end of a disease spectrum with many patients showing overlapping features.

The eponym Mucha–Habermann disease is sometimes applied to the entire spectrum of PL but is often reserved for the particularly severe ulcero-necrotic variant of PLEVA.

Pityriasis lichenoides chronica images

Click for more images of pityriasis lichenoides

Who gets pityriasis lichenoides?

The incidence of PL is unknown, but the disease is rare. It is most common in children and young adults under age 30 but can present at any age. There is a slight male predominance. All races are affected.

What causes pityriasis lichenoides?

The cause of PL is unknown. The main hypotheses are that it may be:

What are the clinical features of pityriasis lichenoides?

PLEVA presents abruptly with a rapidly progressive rash:

  • 10-50 reddish brown, erythematous, ovoid papules, 5-15mm in diameter
  • Mainly on the trunk and proximal extremities
  • Evolution into vesicles, pustules, haemorrhagic crusts, and ulcers
  • Pruritus or burning sensation
  • Most cutaneous lesions heal with transient or persistent hyper- or hypo-pigmentation.
  • Constitutional symptoms are usually mild (see complications below).

PLC presents more slowly over several days with:

  • Larger numbers of small erythematous papules with a brown hue visible on diascopy
  • Mica-like scale on more established lesions
  • Lesions at various stages of evolution
  • Patients often experience periods of relapse and exacerbation.

Patients often show features of both PLEVA and PLC, and PLEVA may evolve into PLC. Mucosal lesions have been reported.

Pityriasis lichenoides acuta
 

How do clinical features vary in differing types of skin?

Dark-skinned patients, particularly children, may present with widespread hypopigmentation and prominent facial involvement. The definitive signs of pityriasis lichenoides may be very subtle.

What are the complications of pityriasis lichenoides?

  • Ulceronecrotic lesions may heal with varioliform scarring.
  • A rare severe form of PLEVA (Febrile Ulceronecrotic Mucha–Habermann Disease) has systemic features of malaise, fever, lymphadenopathy, arthritis, and/or bacteraemia. There may be mucosal, gastrointestinal, and pulmonary involvement. Mortality up to 25% is reported.
  • The psychological impact should not be overlooked, particularly when skin lesions appear on more easily visible areas such as the face and upper arms.

How is pityriasis lichenoides diagnosed?

The diagnosis can often be made on clinical grounds but is usually confirmed with a skin biopsy, which helps to exclude other important differential diagnoses.

Histological features of PLEVA include:

  • A wedge-shaped deep dermal and superficial lymphohistiocytic infiltrate
  • Parakeratotic scale and crust, with thinning of the granular layer
  • Interface dermatitis with basal cell necrosis and vacuolation
  • Epidermal spongiosis and necrosis in more developed lesions
  • Extravasated erythrocytes.

In PLC there is usually:

  • A superficial dermal infiltrate
  • Focal parakeratosis
  • Preservation of the granular layer
  • Focal loss of the dermo-epidermal interface.

Dermoscopy may be useful, particularly to distinguish PLC from guttate psoriasis or pityriasis rosea.

Other tests, such as screening for viral, bacterial, and toxoplasma infection may be considered, depending on the severity of the presentation.

What is the differential diagnosis for pityriasis lichenoides?

What is the treatment for pityriasis lichenoides?

It is important to recognise that there have been no randomised controlled trials regarding treatment, and the natural history of pityriasis lichenoides makes interpretation of anecdotal reports difficult.

What is the outcome for pityriasis lichenoides?

Pityriasis lichenoides et varioliformis acuta typically resolves within a few weeks. However, this can be variable and PLEVA may evolve into PLC or a scar. Pityriasis lichenoides chronica typically lasts several months, but some cases can wax and wane for several years.

Click for images of pityriasis lichenoides

 

References

  • Ankad BS, Beergouder SL. Pityriasis lichenoides et varioliformis acuta in skin of color: new observations by dermoscopy. Dermatol Pract Concept. 2017;7(1):27–34. Published 2017 Jan 31. doi:10.5826/dpc.0701a05. Journal
  • Bellinato F, Maurelli M, Gisondi P, Girolomoni G. A systematic review of treatments for pityriasis lichenoides. J Eur Acad Dermatol Venereol. 2019;33(11):2039–49. doi:10.1111/jdv.15813. Journal
  • Bowers S, Warshaw EM. Pityriasis lichenoides and its subtypes. J Am Acad Dermatol. 2006;55(4):557–76. doi:10.1016/j.jaad.2005.07.058. Journal
  • Jowkar F, Namazi MR, Bahmani M, Monabati A. Triggering of pityriasis lichenoides et varioliformis acuta by radiocontrast iodide. J Dermatolog Treat. 2008;19(4):249–50. doi:10.1080/09546630701713493. Journal
  • Jung F, Sibbald C, Bohdanowicz M, Ingram JR, Piguet V. Systematic review of the efficacies and adverse effects of treatments for pityriasis lichenoides. Br J Dermatol. 2020;183(6):1026–32. doi:10.1111/bjd.18977. Journal
  • Khachemoune A, Blyumin ML. Pityriasis lichenoides: pathophysiology, classification, and treatment. Am J Clin Dermatol. 2007;8(1):29–36. doi:10.2165/00128071-200708010-00004. Journal
  • Lane TN, Parker SS. Pityriasis lichenoides chronica in black patients. Cutis. 2010;85(3):125–9. Journal
  • Magro C, Guo R, Nguyen GH, Tsang H, Momtahen S. Pityriasis lichenoides-like drug reaction: A clinical histopathologic study of 10 cases. Dermatol Online J. 2017;23(11):13030/qt7xd8j71z. Published 2017 Nov 15. Journal

On DermNet NZ

Other websites

Books about skin diseases

 

Related information

Sign up to the newsletter