Skin disorders in pregnancy

1) POLYMORPHIC ERUPTION OF PREGNANCY - 

- Typically begins in abdominal striae as erythematous oedematous papules. 
- Typically spares scalp, face, palms, soles and mucous membranes. 
- Bullae do not occur
- not an auto-immune disease and is not associated with adverse fetal outcome

2) PEMPHIGOID (Herpes) GESTATIONIS - 

- Specific inflammatory dermatosis of pregnancy. 

- Rare and associated with other auto-immune disorders. 

- Presents with clusters of vesicles and bullae and is associated with other auto-immune diseases and HLA-B8 and DR3. 

- Characterised by deposition of complement in cutaneous basement membrane on direct immunofluorescence.  

- Mean gestation at onset is 21 weeks. 
- 20% present post-partum. 
- Lesions first develop in the umbilicus and spread to the trunk and linbs

- Antihistamines can be safely used in pregnancy.

Pemphigus in pregnancy

- Presents with clusters of vesicles and bullae and is associated with other auto-immune diseases and HLA-B8 and DR3  
- Starts within umbilicus and spreads to involve limbs, palms and soles  
- May improve in later pregnancy but 50-75% experience exacerbation within 24-48 hours of delivery
- 5% of neonates may develop bullous lesions  
- Possible increased risk of adverse perinatal outcome - fetal growth and well-being should be monitored
- Treatment is with topical corticosteroids and oral anti-histamines or oral prednisolone in severe cases in pregnancy although methotrexate and azathioprine are used in non-pregnant.