• Characterised by the accumulation of 'fish-like' scales due to abnormal epidermal cell kinetics
  1. Autosomal dominant Icthyosis
  2. Icthyosis vulgaris – most common type
  3. X-linked icthyosis (seen in boys only)
  • Autosomal recessive Icthyosis – more severe than the dominant form
  1. Lamellar icthyosis
  2. Icthyosiform erythroderma
Icthyosis vulgaris
  • Begins in the first year of life
  • Dry, scaly skin over the extensor aspects of the arms and legs
  • The scales are larger over the lower extremities
  • Mild keratoderma or (thickening of the skin over the palms and soles)
  • The dryness becomes worse during winters and improves in summers and humid weather
  • Histologically, the only abnormality detectable is a much diminished granular cell layer.
X-linked ichthyosis
  • Deficiency of steroid sulphatase
  • The scales are dirty brown in colour and affect both the extensor and flexural surfaces of the extremities with prominent involvement of the neck and trunk • These male children are often the products of postmature pregnancies and difficult labours.
  • Associated disorders: cryptorchidism, ectropion
Acquired icthyosis:
  • The most important cause underlying malignant disease – particularly lymphoma –such as Hodgkin's disease
Exam Question
  • Pigmentation and icthyosis are side effects of Clofazimine.
  • Icthyosis may be associated with Hodgkin's disease,AIDS,Hypothyroidism.
  • A male child with cryptorchidism presents with large black scales on body flexures. Skin biopsy showed hyper granulosis & steroid sulfatase deficiency. Probable diagnosis is X- linked icthyosis nigra.
Don't Forget to Solve all the previous Year Question asked on Icthyosis