Ichthyosis: Classification

International experts settled on the following classification of ichthyoses in the fall of 2010:

Primary ichthyoses
Isolated common ichthyoses
  • Ichthyosis vulgaris
  • X-linked recessive ichthyosis
Isolated congenital ichthyoses
  • Lamellar ichthyoses:
    • Autosomal recessive lamellar ichthyosis.
    • Non-bullous congenital ichthyosiform erythroderma
    • Autosomal dominant lamellar ichthyosis
  • Epidermolytic (bullous) ichthyosis:
    • Bullous congenital ichthyosiform erythroderma (Brocq).
    • Ichthyosis hystrix (Curth-Macklin).
    • Ichthyosis bullosa (Siemens)
  • Specific ichthyoses:
    • Harlequin ichthyosis
    • Peeling skin syndrome
Common ichthyoses with associated symptoms.
  • X-linked associated steroid sulfatase deficiency.
  • Autosomal recessive multiple steroid sulfatase deficiency.
  • Refsum syndrome
Congenital ichthyosis with associated symptoms.
  • KID (keratitis-ichthyosis-deafness (deafness) syndrome; synonyms: hystrix-like ichthyosis with deafness; HID syndrome.
  • X-linked dominant – chondrodysplasia punctata type 2 (Happle syndrome; Conradi-Hünermann-Happle syndrome).
  • Ichthyosis linearis circumflexa (Comél-Netherton syndrome).
  • Trichothiodystrophy
  • Sjögren-Larsson syndrome
  • Ichthyosis follicularis with atrichia and photophobia (IFAP syndrome).
  • Chanarin-Dorfman syndrome
Secondary ichthyoses
Secondary ichthyosis as paraneoplasia
  • Malignant lymphoma
  • Visceral carcinomas
Secondary ichthyosis associated with infections
  • Leprosy
  • Syphilis
  • Tuberculosis
Secondary ichthyosis associated with vitamin deficiency
  • Vitamin A deficiency
  • Vitamin B6 deficiency
  • Nicotinic acid deficiency (vitamin B3) → pellagra
Drug-induced secondary ichthyosis

* was withdrawn from the market in 2013

Other secondary ichthyoses
  • Senile skin
  • Trisomy 21 (Down syndrome)
  • Hypothyroidism (hypothyroidism)
  • Long-term dialysis
  • Sarcoidosis

Another common classification of ichthyosis forms is as follows:

Designation (Known) altered proteins (known) gene mutation Inheritance
Vulgar ichthyoses – without other characteristics.
Ichthyosis vulgaris Filaggrin FLG autosomal semidominant
X-linked recessive ichthyosis vulgaris (XRI) Steroid sulfatase STS X-linked recessive
Vulgar ichthyoses – with additional features
Refsum Syndrome Phytanoyl-CoA hydroxylase, peroxin-7. PHYH, PEX7 autosomal recessive
Congenital ichthyoses – without other characteristics
Lamellar ichthyoses Transglutaminase-1 TGM1, ichthyin, CYP4F22, ABCA12 autosomal recessive
Congenital ichthyosiform erythroderma (CIE) Transglutaminase-1, 12R-lipoxygenase-3. TGM1, ALOX12B, ALOXE3, ABHD5, ichthyin. Autosomal recessive
Bullous congenital ichthyosiform erythroderma Brocq (epidermolytic hyperkeratosis (EHK)) Keratins KRT1, KRT10 autosomal dominant
Bullous ichthyosis Siemens Keratin-2e KRT2E autosomal dominant
Ichthyosis hystrix type Curth-Macklin Cytokeratin-1 KRT1 autosomal dominant
Harlequin ichthyosis (ichthyosis gravis) ABCA12 autosomal recessive
Congenital ichthyoses – with additional features
KID syndrome (engl. keratitis ichthyosis deafness); erythrokeratoderma of Burns. Connexin-26 GJB2 autosomal dominant
Comél-Netherton syndrome Serine protease inhibitor LEKTI SPINK5 autosomal recessive
Sjögren-Larsson syndrome Fatty acid aldehyde dehydrogenase ALD3H2 autosomal recessive
Tay syndrome TFIIH helicase XPB ERCC3 autosomal recessive