What is the updated protocol for diagnosis and management of Pruritic Urticarial Papules and Plaques (PUPP) of pregnancy?

Updated Protocol for Diagnosis and Management of PUPP (Polymorphic Eruption of Pregnancy)

PUPP is a benign, self-limited dermatosis of pregnancy that requires only symptomatic treatment with topical corticosteroids and emollients, with no risk to mother or fetus. 1, 2

Diagnosis

Clinical Presentation

• Onset: Typically third trimester (most common), though can occur earlier 2, 3
• Primary location: Erythematous urticarial papules and plaques beginning within abdominal striae, then spreading to proximal thighs, legs, back, buttocks, arms, and breasts 2, 3
• Key distinguishing feature: Periumbilical sparing is characteristic 2
• Pruritus pattern: Intense itching, unlike intrahepatic cholestasis which predominantly affects palms and soles and worsens at night 4
• Rash characteristics: Urticarial plaques, papules, and occasionally erythema multiforme-like target lesions; true bullae are NOT seen in PUPP 3, 5

Physical Examination Findings

• Look for symmetric eruption of papules and urticarial lesions on abdomen and proximal extremities 3
• Assess for excoriations from scratching (which can occur but are secondary) 4
• Critical distinction: Face, palms, and soles are usually spared (though rare cases with palmoplantar involvement exist) 5
• Absence of vesicles and bullae helps differentiate from pemphigoid gestationis 5

Differential Diagnosis to Exclude

The key is distinguishing PUPP from more serious conditions:

• Pemphigoid gestationis: Look for true bullae formation (not present in PUPP), requires skin biopsy with direct immunofluorescence showing linear C3 deposition at basement membrane 2, 5
• Intrahepatic cholestasis of pregnancy: Pruritus WITHOUT rash, predominantly palms/soles, worse at night, requires serum bile acid testing (>10 μmol/L diagnostic) 4
• Atopic eruption of pregnancy: Eczematous rash on face, neck, flexural areas rather than abdomen 4

Laboratory and Histologic Evaluation

• Routine labs NOT required for typical presentations 2, 3
• Skin biopsy indications: Atypical presentation, concern for pemphigoid gestationis, or diagnostic uncertainty 2, 5
• Expected histology if performed: Mild nonspecific lymphohistiocytic perivasculitis without specific diagnostic features 3
• Immunofluorescence: Negative (helps exclude pemphigoid gestationis) 2, 5

Management Protocol

First-Line Treatment (Start Immediately)

Apply moderate-potency topical corticosteroids twice daily to affected areas as primary therapy. 1, 6

• Specific agent: Fluticasone propionate 0.05% lotion (Class 5, low-medium potency) twice daily has demonstrated complete resolution within one week 6
• Alternative agents: Other moderate-potency topical corticosteroids are appropriate 1, 3
• Avoid: Very high-potency topical corticosteroids initially—moderate potency is sufficient and safer 1
• Duration: Continue until symptoms resolve, typically within 1-6 weeks postpartum 3

Adjunctive Measures (Implement Concurrently)

• Emollients: Apply regularly, especially after bathing, to maintain skin barrier function 1, 7
• Oral antihistamines: Diphenhydramine for pruritus control (safe in pregnancy) 3
• Clothing modifications: Loose, breathable clothing from natural fabrics to reduce friction 1, 7
• Skin care: Maintain dryness in affected areas 1, 7

Escalation for Refractory Cases (Rarely Needed)

If symptoms persist despite topical therapy, consider short course of oral prednisolone. 1

• Preferred systemic corticosteroid: Prednisolone (90% inactivated by placenta, making it safest option) 1
• Avoid: Betamethasone and dexamethasone (cross placenta more readily) 1
• Important caveat: Systemic corticosteroids are rarely necessary for PUPP 1, 3

Critical Safety Points

Maternal and Fetal Prognosis

• Maternal outcome: Completely benign, no long-term sequelae 2, 3
• Fetal outcome: No fetal wastage or adverse effects reported 2, 3
• Recurrence: Does NOT typically recur in subsequent pregnancies 2, 3
• Resolution timeline: Clears prior to delivery (33% of cases), within 1 week postpartum (60%), or by 6 weeks postpartum (remaining cases) 3

Common Pitfalls to Avoid

• Do not delay treatment waiting for spontaneous resolution—symptomatic relief improves quality of life significantly 2, 3
• Do not use systemic azole antifungals if fungal infection suspected (especially first trimester)—use topical nystatin instead 1
• Do not prescribe very potent topical corticosteroids for initial management 1
• Do not misdiagnose as pemphigoid gestationis—this leads to unnecessary anxiety and potentially harmful treatment, as pemphigoid gestationis has fetal implications 2, 5

When to Obtain Dermatology Consultation

• Atypical presentation (early onset, unusual distribution, presence of vesicles/bullae) 5
• Diagnostic uncertainty between PUPP and pemphigoid gestationis 2, 5
• Failure to respond to moderate-potency topical corticosteroids within 1-2 weeks 6