Prurigo, Pruriginous Eczema, and Lichenification
Authors: M. Morris
Journal: BMJ (1912)

HEBRA was not the first to describe the prurigo wllich is specially associated with his name.It had already been described, though not clearly discriminated, by Willan under the name of lichen agrius, and by Cazenave, Devergie, and other French writers under the designation of lichen agrius.But Willan's prurigos included all affections in whiclh itching is associated witlh a special eruption and othler phenoniiena; thus lhe recognized general prurigos and a number of local prurigos prurigo of the arnus, of the prepuce, of the scrotum, of the urethra, of the vulva, of the pubes; and he ranked them with strophulus and the so-called lichens of the day in the Order of the Papules.To Erasmus Wilson prurigo was ,simiply "a pruritus associated witlh an organic change in tlle tissues of the skiii," and its pathognomonic charac- teristic was the pruritus-" a pruritus without obvious or apparent cause."In Wilson's day, therefore, the dis- tinction between prurigo and pruritus had not emerged, and dermatology is perhaps indebted to Hebra at least as i11uch for hiis insistence upoll this distinction as for his classic description of the severe form of prurigo known by his nanme.In limiting the term "prurigo," however, to a single type of the aSfection, Hebra fell short of the truthl.To Ilim prurigo was an incurable and ultimately fatal affection, beginning in infancy as an urticaria, which is soon followed by characteristic papules that give rise to intense itching.Enlargement of the lymplhatic glands follows, and later the skin undergoes the changes now known as lichenification.Kaposi saw that hlis master had described only the grave form of a disease whiclh sonietinies manifests itself in a nilder form, _prurigo mitis, not naecessarily incurable, and A;howing no tendency to develop into the severer type.French dermatologists were quick to seize upon the same error, and also to question another of the Vienna nmaster's statenients-namely, that the papules precede tll itching.On these points they have long been virtually agreed, but there have been and still are very considerable differences among themselves.Thus VidalI preferred to style the prurigo of Hebra a lichen, maintained that from the anatomico-pathiological point of view prurigo is only a large papule of lichen, or lichen only a small papule of prurigo, and declared that it is not rarely cured.Besnier2 included among the prurigos many other itching condi- tions which he had separated from the eczema group, qualifying them all as diathetic prurigos because he regarded them as associated with individual conditions of tissues and of organs, provoked or maintained by an abnormal mode of nutrition.To him prurigo was nothing more than an itching dermatosis acconipanied by a visible eruption-a position not very dissimilar from Willan's.Brocqi differs from both Vidal and Besnier.In his view there are three forms of prurigo: (1) Prurigo simplex, with no eezematization or lichenification-the urticaria papulosa or strophulus of many otller writers; (2) prurigo of Hebra, which may be either severe or mild, and of wvhich the milder forms may begin much later in infancy and may die away, sometimes within a few months; and(3) pr-rigo ferox, in whichl the papules are larger and harder, the itclhing is friglhtful, and the gland enlargement considerable, but in which the lichenification is less exten- sive than in the prurigo of Hebra.Darier4 also recognizes three forms of prurigo, which, however, do not tally com- pletely with Brocq's.The first, like Brocq's, is prurigo simnplex, or strophulus (urticaria papulosa).The second he styles prurigo of Hebra, but lhe regards it as including not only (a) the type of Hebra-Kaposi, but also (b) a mild French type, and (c) prurigo ferox.Ifis second prurigo, therefore, includes Brocq's second and third types.Darier's third prurigo is styled prurigo vulgaris, which may be either (a) diffused, or (b) circumscribed.This corresponds