Skin-nontumor / Clinical dermatology
Other dermatoses
Polymorphous light eruption

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 20 July 2016, last major update August 2011

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Polymorphous light eruption

Cite this page: Polymorphous light eruption. website. Accessed October 21st, 2016.
Definition / General
  • The most common photodermatosis
  • Presents in young adults as recurrent erythematosus papules, vesicles or plaques on face, chest, upper back and extremities
  • Onset of lesions 18 - 24 hours after light exposure, usually in spring / summer
  • Associated with thyroid disease or lupus in some patients
  • Juvenile spring eruption appears to be either a form of polymorphous light eruption or a closely related disorder
  • Use photo testing to establish diagnosis
Clinical Images

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Polymorphic light eruption on arm

Micro Description
  • Perivascular lymphohistiocytic infiltrate in superficial and sometimes deep dermis
  • Papillary dermal edema; epidermal acanthosis, spongiosis, occasional dyskeratotic cells and lymphocytic exocytosis
  • Basal cell vacuolation is mild
  • Periadnexal involvement may be seen; variable increase in eosinophils and neutrophils
Micro Images

Images hosted on other servers:

Polymorphous light eruption

Positive Stains
  • Direct immunofluorescence shows C3, IgM and IgG at basal layer of dermoepidermal junction
Differential Diagnosis
  • Actinic reticuloid: dense cellular and interstitial infiltrate of papillary and reticular dermis that may extend to subcutaneous fat; composed of variable lymphocytes, histiocytes, eosinophils and plasma cells; multinucleated giant cells are conspicuous; also large atypical hyperchromatic cerebriform lymphoid cells and blast forms
  • Gyrate erythema such as lymphocytic infiltration of Jessner
  • Reticulae erythematous mucinosis: has dermal mucin, not present in polymorphic light eruption
  • SLE
Additional References