17.2 Porphyria Cutanea Tarda (1)

 

Definition

 
 
 Chronic disturbance in hepatic porphyrin synthesis, 40-70 years of age, < 1 % of population, 1/3 of all porphyrias, M:F = 2:1.
 
 

Aetiology & Pathogenesis

 
 
 Genetic (autosomal dominant) or acquired: deficiency in uroporphyrinogen-III decarboxylase.
  • Triggers -> Alcohol! Medications (antimycotics, analgesics, barbiturates, estrogens, chloroquine), poisoning (lead, arsenic, wheat treated with hexachlorbenzole). Liver infections: HIV+HCV! 

 
 
 

Symptoms

 
 

 
  • Blistering in light-exposed areas and with minimal trauma (face, backs of hands)
  • Heal with milia and atrophy
  • Hypertrichosis on cheeks and temples
  • Pseudoscleroderma (rare)
  • Discolored urine
 
 

Laboratory

 
 
 Blood: Elevated Re levels, liver enzymes increased
Urine: Increased levels of uroporphyrins (I > III)
Stool: Increased levels of porphyrins
 
 

Histology

 
 
 Subepidermal blister, thickened basement membrane, thickened vessels.
 
 

Differential Diagnosis

 
 
 Other blistering disorders.
 
 

Therapy

 
 
 
  • Topical: sunscreens (SPF/LSF > 30).
  • Systemic: avoidance of triggers (Alcohol, hepatotoxic medications), phlebotomy to reduce iron stores, chloroquine in very low dosages.