History of Seborrheic Dermatitis: Conceptual and Clinico-Pathologic Evolution.

Seborrheic dermatitis is an inflammatory and chronic disease with a high incidence and prevalence (1% to 3% in the general population, 3% to 5% in young adults, and 40% to 80% in HIV-positive individuals). Although the condition was first described in 1887, its clinical aspects and clinical forms have still not been well individualized, nor has its etiopathogenesis been fully elucidated. The disease, despite having clinical features similar to dermatitis, does not have the same histopathologic features or the same progressive clinical behavior. This contribution reviews the history of seborrheic dermatitis.

Acne pathogenesis: history of concepts.

From the first reliable descriptions of acne in the early 19th century, dermatologists recognized it as a disease of the pilosebaceous follicle. Until the middle of the 20th century, they hypothesized that seborrhoea, follicular keratosis and microorganisms could be individually responsible for the acne lesions. Inflammation was only regarded as the final and inescapable step of the acne process. Although the importance of these factors has been reevaluated, recent works still regarded them as mandatory. In the 1970s, the onset of isotretinoin dramatically improved acne management. It also provided great opportunities for a better understanding of the pathogenic factors of acne. This study analyzes their genesis and development from the seminal contributions until recent advances.

Keratosis lichenoides chronica: proposal of a concept.

It has been a subject of controversy whether keratosis lichenoides chronica (KLC) is a distinctive inflammatory disease of the skin or whether it represents a manifestation of another well-known disease, such as lichen planus, lupus erythematosus, or lichen simplex chronicus. In search of clear criteria for diagnosis of KLC the entire literature pertinent to the subject was studied and findings clinical and histopathologic as they were telegraphed in them were compared with a patient of my own experience. Review of the literature reveals more than 60 patients in whom the diagnosis of KLC was made. Three categories emerge based on whether the findings presented in a particular article (1) do not permit any diagnosis to be rendered; (2) do allow a diagnosis specific to be made, such as of lichen simplex, lichen planus, or lupus erythematosus; or (3) do not correspond to any disease well defined, such as lichen simplex, lichen planus, lupus erythematosus, but seem to show attributes morphologic, clinically and histopathologically, that are repeatable. Patients diagnosed as having KLC obviously represent a potpourri of different diseases, the most common of them being lichen simplex chronicus, lichen planus, and lupus erythematosus. Fewer than 25 patients reported on, however, presented themselves with lesions very similar to one another clinically, namely, an eruption that involved the face in a manner reminiscent of seborrheic dermatitis and with tiny papules on the trunk and extremities, which assumed linear and reticulate shapes by way of confluence of lesions. Individual papules were infundibulocentric and acrosyringocentric. Findings histopathologic were those of a lichenoid interface dermatitis affiliated with numerous necrotic keratocytes and covered by parakeratosis housing neutrophils in staggered fashion. These patients seem to have an authentic and distinctive condition that is exceedingly rare. In conclusion, the diagnosis of KLC should be made only for patients who present themselves with features clinical and findings histopathologic that resemble closely those of what is summarized in this article under category 3.