J. de Weert

Alopecia areata: A Clinical Study

100 cases of alopecia areata are examined and the possible relationship with the presumed etiological factors (atopy, autoimmunity and psychosomatics) are looked for. When atopy or autoantibodies are present alopecia areata always runs a serve course. It is, however, impossible to establish a definite etiological relation between atopy or autoimmunity and alopecia areata.

Le syndrome de Lyell

In Lyell’s disease different clinical patterns can be observed: (a) an acute scarlatiniform erythema, on which more or less extended bullae rapidly appear; (b) a morbilliform erythema, with bullae; (c

Keratosis lichenoides chronica

Description of a case of keratosis lichenoides chronica with presence of blisters. Histologically, the initial lesion seems to be localized at the dermo-epidermal junction. The vessels of the upper de

Morphological changes in the proximal area of the rat's hair follicle during early catagen

SummaryThis electron-microscopic study of the catagen phase shows that the first alteration of regression of the follicle is localized in the papilla, where the cells withdraw their offshoots and break the contact with the basal lamina. Both at the level of the papilla and of the bulb structures appear that increase the cell cohesion. Under the influence of the outer root sheath an upward migration occurs. This is followed by plication and thickening of the basal lamina. The alterations in the connective tissue sheath occur in a further stage. The first signs of autolysis occur in the center of the epithelial column. At the end of the catagen stage macrophages take care of the clearing-up.

Embryogenesis of the hair follicle and hair cycle

Formation of hair follicles starts in utero along with the first anagen stage of the first hair cycle. After the first wave of growth during the postnatal period, in human beings, each follicle has its own growth cycle that behaves independently of its neighbors, so that there is a mosaic pattern of hair replacement. Some synchronization of human hair growth occurs, however, in certain pathological conditions. After a period of continuous growth, involution of the lower part of the follicle occurs. During catagen the follicle passes in an upward migration to the telogen location. The papilla is likewise pulled upward at the end of the catagen stage. Another characteristic feature in catagen is the phenomenon of cell death by apoptosis and, after catagen, the follicle enters in telogen. This stage is only seemingly quiescent, since the germ of the new follicle is already being formed at its base. The first sign of a new anagen phase is mitotic division of the cells in the lower part of the telogen follicle. The active base of the follicle is transformed to a bulb and the entire development of a new hair with its epithelial component and connective tissue envelopes begins again in the same way as in utero, except for two factors: the new follicle does not originate from an epidermal bulge into the dermis, and the old dermal papilla can resume its activity.

Nosology of the Sézary Syndrome

The nosological place of Sezary’s syndrome is studied apropos of two cases. The authors rely on histological, histochemical, electron microscopical and cytogenetical data. This syndrome can be considered as a T-lymphocyte leukaemia.