CONGENITAL ICHTHYOSIS (HARLEQUIN FETUS)

 

Congenital ichthyosis is a lethal disorder characterized by massive overgrowth of the keratin layer of the fetal skin. The skin has a parchment-like appearance with deformities of the mouth, ears and eyes (ectropion-like condition).

  • Mode of inheritance is thought to be autosomal recessive (1).
  • In its most severe form infants only live hours to a few days (2).
  • Pathology: the skin condition is thought to be caused by an inborn error of epidermal keratinization or possibly a defect in lipid metabolism.

There is massive increase in the epidermal skin layer (3). Prenatal diagnosis by skin biopsy has been reported (4-6). In the normal fetus skin keratinization does not begin until 22-24 weeks gestation (7). The fetal palms, soles, face and scalp show keratinization earlier than the trunk and limbs (7). Skin biopsy demonstrates early onset hyperkeratinization. A single case of a negative skin biopsy has been reported (8).
 

 

 

ULTRASOUND
  • Ultrasound may be normal in the second trimester.
  • IUGR.
  • Mouth is fixed in an abnormally wide-open position.
  • The ears are absent or rudimentary and there is marked eclabium.
  • Ectropion¾cystic mass anterior to the orbit.
  • Fixed flexion of the hands. The fetus has difficulty in opening and closing the hands and mouth because of the tight wrapping of the skin.
  • Intra-amniotic debris has been described (9).
  • Thick discontinuous membrane floating in the amniotic fluid (10).The membrane appeared to be fixed to or arise from the fetal thorax and lower abdominal wall. This membrane was found to be sloughed abnormally thickened fetal skin.
  • The "snowflake sign" may be present (reflecting skin particles in the amniotic fluid) (11).
  • Suresh and co-workers (13) suggest that an abnormal femur foot length may be the first sonographic sign of this condition. The femur has a normal length, however the foot is shortened because of the severe restrictive dermopathy. The phalanges, metacarpals and metatarsal are underossified because of the tight wrapping of the skin, leading to a decreased foot length. Short foot length may be evident as early as 22-24 weeks of gestation when the development of the skin is complete.

 

PROGNOSIS

Most infants are stillborn. Live-born do not generally survive more than a few days because of severe restriction of the chest and abdomen resulting in feeding and respiratory problems. Death may also result from sepsis and extensive bacterial infection of the ichthyosis (12).
 

 

REFERENCES
  1. Edmonds HW, Dolan WD. Ichthyosis congenita fetalis, severe type (Harlequin fetus). Bull Int Assoc Med Mus 1951;32:1.
  2. Watson WJ, Mabee LM. Prenatal diagnosis of severe congenital ichthyosis (Harlequin Fetus) by ultrasonography. J Ultrasound Med 1995;14:241-243.
  3. Anton-Lamprecht I. Electron microscopy in the early diagnosis of genetic disorders of the skin. Dermatologica 1978;157:65.
  4. Suzumori K, Kanzaki T. Prenatal diagnosis of harlequin ichthyosis by fetal skin biopsy: report of two cases. Prenat Diagn 1991;11:451.
  5. Elias S, Mazur M, Sabbagha R et.al. Prenatal diagnosis of harlequin ichthyosis. Clin Genet 1980;17:275.
  6. Blanchet-Bardon C, Dumez Y, Labbe F et.al. Prenatal diagnosis of harlequin fetus. Lancet 1983;1:132.
  7. Holbrook KA. Structure and biochemical organogenesis of skin and cutaneous appendages in the fetus and neonate. In: Polin R, Fox WW (eds): Fetal and neonatal physiology Vol I. WB Saunders 1992:527.
  8. Arnold ML, Anton-Lamprecht I. Problems in prenatal diagnosis of the ichthyosis congenita group. Hum Genet 1985;71:301-311.
  9. Montague I, Fox R, Mann R. Intra-amniotic debris identified at ultrasound: a feature of congenital ichthyosis. Ultrasound Obstet Gynecol 1997;9:350-351.
  10. Mihalko M, Lindfors KK, Grix AW et.al. Prenatal sonographic diagnosis of harlequin icthyosis. AJR1989;153:827-828.
  11. Shively CL. Sonographic evaluation of harlequin ichthyosis. JDMS 1999;15:246-248.
  12. Avery GB, Fletcher MA, MacDonald MG. Neonatology, Pathophysiology and management of the newborn. 4th ed. Philadelphia, JB Lippincott 1994, pg425.
  13. Suresh S, Vijayayalakshmi R, Indrani S, Lata M. Short foot length. A diagnosic pointer for Harlequin Ichthyosis. J Ultrasound Med 2004;23:1653-1657.