CORNEOCYTES IN SCALY PARAKERATOTIC DISEASES

Background and Objectives. The stratum corneum of some of the scaly (p arakeratotic) diseases was examined with light and scanning electron m icroscopy (SEM) With the purpose to reveal the importance of this laye r in the diagnosis of some of the diseases associated with the formati on of scales. Materials and Methods, Two biopsies of the skin surface were taken: one, obtained from 80 patients with various parakeratotic scaly diseases and from 25 control subjects, was processed for light m icroscopy; the other biopsy for SEM was taken from 10 control subjects and 25 patients. The diagnoses of these patients were: psoriasis (5 p atients), erythrodermic psoriasis (2 subjects), parapsoriasis (5 patie nts), pityriasis rubra pilaris (5 subjects), pityriasis rosea (3 subje cts), and seborrheic dermatitis (5 subjects). Results, The light micro scopic studies showed that normal corneocytes are of polygonal shape w ith their largest diameter measuring 42 mu m; these cells lacked nucle i. All parakeratotic cells appeared bizarre in shape, smaller than nor mal, and the cells contained a nucleus. With SEM, normal cells appeare d relatively regular in size and shape, trabeculated, and had a flat s urface. Cells examined in all the diseases revealed various sizes, out lines, and trabeculae. Specific surface patterns (print) of diseased c ells were: ''fish-scale'' in psoriasis; ''marbled'' in parapsoriasis, ''rocky stone'' in pityriasis rubra pilaris; ''heart-shaped'' in sebor rheic dermatitis, and semi-crystalloid in pityriasis rosea. Conclusion s. Parakeratosis is characterized not only by the retention of the nuc leus in keratinocytes, but is also characterized by a cell of smaller size. The specific print of a disease helps in the diagnosis. The prin t will change with different stages of a disease.