One patient with lamellar ichthyosis and one patient with ichthyosis vulgaris, both with multiple clear-cell acanthomas on the lower extremities, were studied. Histologic examination showed the typical findings of clear-cell acanthoma, plus intraepidermal nests composed of cell debris and inflammatory cells. Histochemical studies revealed increased dendritic cells with intense nucleotide triphosphatase and acid phosphatase activities. The dendritic cells also contained neutral lipids, well demonstrated by oil red O stain. Electron microscopic examination revealed, in addition to glycogen-containing epidermal cells, dendritic cells and processes in the intercellular spaces. Although indeterminate dendritic cells were found, many contained Langerhans granules and lysosomes. Leukocytes and products of cell degradation were seen in the intercellular spaces, often in relation to the leukocyte nests. Mast cells were observed in the epidermis.
Landry M, Winkelmann RK. Multiple Clear-Cell Acanthoma and Ichthyosis. Arch Dermatol. 1972;105(3):371-383. doi:10.1001/archderm.1972.01620060013003