This 10-year-old boy developed progressive scaling before his first birthday. Physical examination revealed symmetric non inflammatory, light brown polygonal discrete and confluent scales involving the extensor surfaces of the limbs, trunk, face, neck and ears. The antecubital, popliteal and groin areas were spared. Involvement of the neck and preauricular area was severe supporting a diagnosis of X-linked recessive ichthyosis rather than ichthyosis vulgaris. X-linked icthyosis (XLI) was first recognized as a distinct entity by Well and
Kerr in 1965. It is a genetic disorder of keratinization which is caused by
a steroid sulfatase (STS) deficiency resulting from abnormalities in its coding
gene. The STS gene has been mapped to the distal part of the short arm of
the X chromosome (band Xp22.3). Although, most affected individuals have
extensive deletions of the STS gene, point mutations producing complete STS
deficiency have also been reported in a number of patients.
A few female heterozygotes have been reported but males are overwhelmingly
affected. The XLI is usually present at birth or appears during neonatal
period. A dirty face appearance is characteristic due to adherent brown
scales that also involve the scalp, preauricular skin, and posterior neck in
early childhood. As the age advances the scaling becomes more generalized
but usually sparing the flexures and the palmoplantar skin. The scaling
becomes more prominent in winter and regresses in summer. Associated
findings may include corneal opacities, cryptorchidism, EEG changes and slow
delivery of the affected infant because of insufficient cervical dilation.
X-linked icthyosis can be diagnosed by biochemical and genetic analysis.
Topical keratolytics and emollients are the mainstay of treatment.
References: 1. Aviram-Goldring A, Goldman B, Netanelov-Shapira I, et al:
Deletion patterns of the STS gene and flanking sequences in Israeli X-
linked ichthyosis patients and carriers: analysis by polymerase chain
reaction and fluorescence in situ hybridization techniques. Int J Dermatol
2000 Mar; 39(3): 182-7
2. Cuevas-Covarrubias SA, Diaz-Zagoya JC, Rivera-Vega MR, et al: Higher
prevalence of X-linked ichthyosis vs. ichthyosis vulgaris in Mexico. Int J
Dermatol 1999 Jul; 38(7): 555-6
3. Shwayder T. Disorders of keratinization: diagnosis and management. Am J
Clin Dermatol. 2004;5(1):17-29.
diffuse symmetric non inflammatory hyperpigmented scale