Pathology

The pathology of the skin presents no essential differences from the pathology of other parts of the body—that is, the same morbid processes that are met with elsewhere also find expression in the dermal tissues. For instance, congestion, inflammation, hypertrophy, atrophy, oedemas, infiltrations, degenerations, neoplasms, pseudoplasms, ner­vous derangements, etc., are the processes which result in the production of the various lesions that constitute the essential visible characteristics of cutaneous disease. In addition we have certain parasitic invasions, of both animal and vegetable origin. The complex structure of the skin, and of the special organs contained in it, together with the anatomical pecularities of the appendages, give rise to an almost infinite variety of changes.