Can polymorphic light eruption (PMLE) present with a bullous or papulovesicular variant in fair-skinned individuals?

Polymorphic Light Eruption: Bullous and Papulovesicular Variants

Yes, polymorphic light eruption can present with papulovesicular variants, but true bullous variants are not characteristic of PMLE and should prompt consideration of alternative diagnoses.

Clinical Variants of PMLE

PMLE is characterized by multiple morphological presentations, as its name suggests:

• Papulovesicular variant is well-recognized and presents as small papules with vesicles on sun-exposed skin, typically developing 30 minutes to several hours after sun exposure 1
• The papulovesicular lesions are pruritic, erythematous, and occur on photo-exposed areas, healing without scarring 1
• A pinpoint papular variant has been specifically documented, where acute presentations show pinpoint papules and vesicles with erythematous bases 2
• Histologically, the acute papulovesicular variant demonstrates focal vesicle formation, spongiosis, edema, and superficial/deep perivascular lymphocytic infiltrate 2

Important Distinction: True Bullae Are NOT Typical

True bullous (large blister) formation is not a recognized variant of PMLE and should raise concern for other diagnoses:

• The various clinical patterns of PMLE range from small papules and papulovesicular lesions to large papules that coalesce into plaques, but bullae are not described 3
• Multiple comprehensive reviews of PMLE morphology consistently describe papules, vesicles, and plaques, but not bullous lesions 1, 4

Critical Differential Diagnoses When Bullae Are Present

If a patient presents with bullous lesions in sun-exposed areas, consider:

• Bullous pemphigoid - particularly in elderly patients, requires direct immunofluorescence showing linear IgG/C3 deposits at the basement membrane zone 5
• Pseudoporphyria or porphyria cutanea tarda - presents with blisters on sun-exposed areas
• Phototoxic drug reactions - can cause bullous eruptions
• Epidermolysis bullosa acquisita - may be photodistributed

Clinical Pitfalls to Avoid

• Do not diagnose PMLE if true bullae (large, tense blisters) are present - this morphology warrants skin biopsy with direct immunofluorescence to exclude immunobullous disorders 5
• Small vesicles (papulovesicular variant) are acceptable for PMLE diagnosis, but large bullae are not 1, 2
• PMLE can be provoked during PUVA therapy, but this typically manifests as the patient's usual morphology (papules/vesicles), not new bullous lesions 6

Diagnostic Approach for Vesicular vs Bullous Lesions

For small vesicles on papules (papulovesicular variant):

• Consistent with PMLE if history shows recurrent pruritic eruption after sun exposure, healing without scarring 1
• Phototesting may reproduce lesions with UVB or UVA wavelengths 3
• Biopsy shows superficial and deep perivascular lymphocytic infiltrate with focal vesicle formation 2

For true bullae (large blisters):

• Obtain skin biopsy for routine histology AND direct immunofluorescence from perilesional skin 5
• Consider serum for anti-BP180/BP230 antibodies if bullous pemphigoid suspected 5
• Review medication history for phototoxic drugs 5