Differential Diagnosis for Pemphigoid Gestationis vs Pustular Psoriasis of Pregnancy

• Single most likely diagnosis:
  • Pemphigoid gestationis: This is the most likely diagnosis due to its strong association with pregnancy, typically presenting in the second or third trimester with intense itching and blistering of the skin.
• Other Likely diagnoses:
  • Pustular psoriasis of pregnancy: Although less common, pustular psoriasis can occur during pregnancy and presents with widespread pustules on the skin, often accompanied by systemic symptoms such as fever.
  • Polymorphic eruption of pregnancy (PEP): Previously known as pruritic urticarial papules and plaques of pregnancy (PUPPP), PEP is a common skin condition in pregnancy characterized by itchy, papular lesions, typically starting in the abdominal striae.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • HELLP syndrome: A serious condition that can occur during pregnancy, characterized by hemolysis, elevated liver enzymes, and low platelet count. It can present with skin manifestations and is crucial to diagnose early due to its potential for severe maternal and fetal complications.
  • Acute fatty liver of pregnancy: A rare but potentially life-threatening condition that can cause skin manifestations among other systemic symptoms. Early diagnosis is critical for managing the condition and preventing severe outcomes.
• Rare diagnoses:
  • Prurigo of pregnancy: A rare condition characterized by extremely itchy nodules on the skin. While not typically dangerous, it can significantly affect the quality of life and may be confused with other conditions.
  • Intrahepatic cholestasis of pregnancy (ICP): Although primarily known for causing severe itching without a rash, in rare cases, it might be considered in the differential due to its potential to cause skin manifestations in some patients.