The histology of autosomal dominant ichthyosis vulgaris and X-linked ichthyosis was studied using biopsy material from the arm and leg. Their characteristic histology is best demonstrated in the thick scales of the leg. Biopsy specimens from the arm, especially from the delicate scales of autosomal dominant ichthyosis vulgaris, may be similar microscopically to normal skin. Autosomal dominant ichthyosis vulgaris and X-linked ichthyosis are most readily distinguished histologically when specimens are obtained from regions of maximal scaling.
Feinstein A, Ackerman AB, Ziprkowski L. Histology of Autosomal Dominant Ichthyosis Vulgaris and X-linked Ichthyosis. Arch Dermatol. 1970;101(5):524–527. doi:10.1001/archderm.1970.04000050028004