ichthyosis vulgaris (ichthyosis simplex)

Etiology

• frequently associated with atopy
  • atopic dermatitis, allergic rhinitis, intrinsic asthma

Epidemiology

• no sex predilection

Pathology

• compact hyperkeratosis
  • epidermis proliferated normally, but keratin is retained with a resultant thickened stratum corneum
• reduced or absent granular layer
• germinal layer flattened
• electron microscopy:
  • small, poorly formed keratohyalin granules

Genetics

• autosomal dominant
• associated with defects in FLG

Clinical manifestations

• mild generalized hyperkeratosis with xerosis
• distribution
  • generally diffuse
  • most pronounced on lower legs (fish scale pattern)
  • generally sparing of axillae, antecubital & popliteal fossa
  • generally sparing of face, but cheeks & forehead may be involved
• keratosis pilaris
• age of onset 3-12 months of age
• ocular keratopathy is rare

Differential diagnosis

• xerosis
• acquired ichthyosis due to paraneoplastic syndrome
• drug-associated ichthyosis (triparanol)
• X-linked ichthyosis
• lamellar ichthyosis
• generalized dermatophytosis

Management

• prognosis:
  • may improve in summer, humid climates & in adulthood
  • lesions on cheeks during childhood generally improve as an adult
• emollients
• keratolytics
  • propylene glycol 44-60% qhs after bathing with plastic occulsion (plastic suit worn as pajamas) weekly
  • salicylic acid
  • urea 10-20%
  • alpha-hydroxy acids (glycolic acid, lactic acid)
• systemic retinoids
  • isotretinoin
  • acitretin
  • etretinate

Notes

• Support group: Foundation for Ichthyosis & Related Skin Types (FIRST)

More general terms

• ichthyosis; erythrokeratodermia variabilis

Additional terms

• 13-cis retinoic acid; isotretinoin (Accutane)
• acitretin (Soriatane)
• etretinate (Tegison)
• hyperkeratosis
• keratosis pilaris
• salicylic acid
• xerosis (dry skin)

Database

• OMIM: https://mirror.omim.org/entry/146700