Skin nontumor

Lichenoid and interface reaction patterns

Pityriasis lichenoides chronica



Last author update: 14 March 2022
Last staff update: 24 June 2022

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PubMed Search: Pityriasis lichenoides chronica [title]

Gülçin (Güler) Şimşek, M.D.
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Cite this page: Şimşek G. Pityriasis lichenoides chronica. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorPLC.html. Accessed August 10th, 2022.
Definition / general
Essential features
  • Asymptomatic red-brown and small sized papulosquamous lesions arise in crops and usually involve trunk, upper extremities and buttocks
  • Parakeratosis, spongiosis, intraepidermal lymphocytes and erythrocytes, superficial perivascular or lichenoid lymphocytic infiltrate, focal interface change, melanophages and extravasated erythrocytes
Terminology
  • Guttate parapsoriasis, chronic lichenoid pityriasis, parapsoriasis lichenoides chronica
ICD coding
  • ICD-10: L41.1 - pityriasis lichenoides chronica
Epidemiology
Sites
  • Trunk, proximal extremities and buttocks
Pathophysiology
  • Not exactly understood; infectious and drug related hypersensitivity reactions and premycotic lymphoproliferative disorder are the main hypotheses
Etiology
  • Associated with genetic and environmental factors (viral infections, autoimmune diseases, drug and vaccine induced, etc.); there is some evidence of association with lymphoproliferative disorder
Clinical features
  • Acute form: erythematous, vesiculopustular and necrotic lesions with the symptoms of itching and burning
  • Chronic form: reddish brown papules, postinflammatory hypo and hyperpigmentation can be seen
  • Upper limbs and flexor surfaces are more frequently involved than lower limbs and extensor surfaces; central, diffuse and peripheral forms can occur and atypical presentation may appear (Dermatol Pract Concept 2013;3:7, J Drugs Dermatol 2019;18:690)
Diagnosis
Laboratory
  • Some patients have elevated serum immune complexes
Prognostic factors
  • Relapsing and remitting course persists for months or a few years
  • Treatment may or may not relieve symptoms
Case reports
Treatment
  • Topical steroids
  • Topical immunomodulators (tacrolimus, pimecrolimus)
  • Oral antibiotics (erythromycin, tetracycline such as doxycycline)
  • Phototherapy
  • Systemic steroids
  • Reference: Am J Clin Dermatol 2007;8:29
Clinical images

Contributed by Mark R. Wick, M.D.

Arms

Breast skin



Images hosted on other servers:

Oval red-brown papulosquamous lesion

Flattened scaly brown papules

Microscopic (histologic) description
  • Parakeratosis, mild to moderate acanthosis, mild spongiosis, sparse necrotic keratinocytes, minimal vacuolar degeneration of the basal layer, focal exocytosis of small numbers of lymphocytes and intraepidermal erythrocytes
  • Mild superficial perivascular and lichenoid lymphocytic infiltrate, focal interface change, melanophages and extravasated erythrocytes without (occasionally focal) fibrinoid necrosis of vessels; neither eosinophils nor plasma cells present
  • Dilatation and congestion of superficial vessels, papillary dermal edema and pigment incontinence
  • Pityriasis lichenoides et varioliformis acuta (PLEVA, acute form of the disease) is similar to PLC but with more pronounced histologic features: more interface damage, more inflammation, more erythrocytes in dermis and epidermis
    • Acute and chronic refer to the characteristics of the lesions
  • Also shares clinical and some immune histologic features with lymphomatoid papulosis (Am J Surg Pathol 2012;36:1021)
  • CD4:CD8 ratio > 1; monoclonal T cell population may mimic MF (Indian J Dermatol 2012;57:424)
  • Some cases reported as a form of MF and T cell dyscrasias arising in association with pitryiasis lichenoides in children and adults (J Turk Acad Dermatol 2014;8:1483c3, Australas J Dermatol 2021 Nov 9 [Epub ahead of print])
  • Adnexotropism was described (Am J Dermatopathol 2020;42:1)
Microscopic (histologic) images

Contributed by Gülçin (Güler) Şimşek, M.D. and Mark R. Wick, M.D.

Parakeratosis and exocytosis of lymphocytes

Parakeratosis, spongiosis and exocytosis of lymphocytes

Perivascular and lichenoid lymphocytic infiltrate

Lichenoid interface dermatitis with melanophages

Extravasated erythrocytes, fibrinoid necrosis


Intraepidermal erythrocytes and lymphocytes

Exocytosis of lymphocytes / extravasated erythrocytes

Breast skin

Immunofluorescence description
  • IgM and C3 in the walls of the superficial dermal blood vessels and along the dermoepidermal junction in some patients
Sample pathology report
  • Trunk, papulosquamous lesion, punch biopsy:
    • Lichenoid / perivascular interface dermatitis (given the history, compatible with pitryiasis lichenoides chronica) (see comment)
    • Comment: Parakeratosis, mild superficial perivascular and lichenoid lymphocytic infiltrate, focal interface change, exocytosis of small numbers of lymphocytes and extravasated dermal and intraepidermal erythrocytes. The histologic features are consistent with pitryiasis lichenoides chronica. Clinicopathologic correlation is recommended.
Differential diagnosis
Board review style question #1


An 11 year old boy presented with depigmented papulosquamous lesions on the anterior part of the trunk and upper extremities. Clinical picture and biopsy reveal the findings shown in the images above. What is the most likely diagnosis?

  1. Lichen planus
  2. Lichenoid drug eruption
  3. Mycosis fungoides
  4. Pityriasis lichenoides chronica
  5. Pityriasis lichenoides et varioliformis acuta
Board review style answer #1
D. Pityriasis lichenoides chronica

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Reference: Pityriasis lichenoides chronica
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