Skin manifestations of the reticuloses.

The conception of the reticulo-endothelial system belongs to the realm of experimental pathology. The reticuloses, a group of disorders primarily affecting that system are, therefore, a concept of pathology and their clinical manifestations must be diverse. Indeed, even among pathologists, opinions are divided as to the criteria which govern admission to the group. It would be widely conceded that reticuloses are liable to involve cells of the reticulo-endothelial system in whatever part of the body they occur, and since the skin is a very readily observed organ in which reticulo-endothelial elements are numerous, it is not surprising that most reticuloses have dermatological manifestations-though some much more frequently than others. At the present time the reticulosis group is made up of a number of syndromes which in their dermatological manifestations are characterized by a massive infiltration of the dermis with cells of proved or presumed origin from the reticuloendothelial system. As Goldsmith (I944) pointed out, it would be absurd to make the condition that the cause must be unknown, i.e. that no infective or similar agent has been identified. At the same time, it is impossible entirely to escape the notion that the chronic granulomatous process of Hodgkin's disease is acceptable as a reticulosis, whereas to include the widespread chronic granulomatoses of the well-known infections would be to broaden the concept of reticulosis until it loses its meaning. With very few exceptions then, the causes of the reticuloses are unknown. To the clinician a purely pathological classification is not entirely satisfactory; a purely clinical classification is still more unsatisfactory since a single entity such as mycosis fungoides may produce clinical manifestations of great diversity. These manifestations may be grouped into three classes and it is from this purely clinical aspect that the reticuloses are now considered; such a clinical classification cuts across the pathological classification and is in no way a substitute for it. The three types of manifestation referred to are: (I) Generalized pruritus; (2) superficial eruptions; and (3) infiltrated or tumour-like lesions.