Skin nontumor
Dermal perivascular and vasculopathic reaction patterns
Polymorphous light eruption
Last author update: 1 August 2011
Last staff update: 18 January 2021
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PubMed Search: Polymorphous light eruption
Table of Contents
Definition / general | Clinical images | Microscopic (histologic) description | Positive stains | Differential diagnosis | Additional referencesCite this page: Hamodat M. Polymorphous light eruption. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorpolymorphouslighteruption.html. Accessed April 25th, 2024.
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
Microscopic (histologic) 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
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
