Porphyria cutanea tarda

Definition

• A defect in the heme synthesis pathway that causes cutaneous manifestations in adults
• Either type 1 (sporadic) or type 2 (familial)

Pathophysiology

• A defect in uroporphyrinogen decarboxylase, which normally converts uroporphyrinogen I and III to coproporphyrinogen I and III

Clinical Manifestations

• Blistering skin lesions on the back of the hands
  • They rupture and crust over, leaving atrophy and scarring
  • Scarring and calcification can look like sclerosis
• Lesions may appear on forearms, face, legs, and feet
• May have hyperpigmentation and hypertrichosis of the face
• No neurological manifestations
• Often have liver disease, and are higher risk for hepatocellular carcinoma

Investigations

• Porphyrins in liver, plasma, urine, or stool are elevated
  • Urinary porphyrins include uroporphyrins and heptacarboxylate porphyrin
• Urinary ALA level may be elevated
• PBG level is normal

Management

• Avoid alcohol
• Stop estrogen supplements, iron supplements, and any other drugs that may be exacerbating
• Repeated phlebotomy to reduce hepatic iron stores
  • Remove 1 unit every 1 to 2 weeks
  • Remission may require more than six phlebotomies
  • Follow the serum porphyrin levels every 6 to 12 months; they should decrease
• Hydroxychloroquine is second-line
• Liver imaging to screen for hepatocellular carcinoma