Histiocytic Skin Diseases in Dogs and Cats

This group of diseases encompasses several conditions that involve abnormal proliferation of Langerhans cells (LC) or dermal (or other interstitial tissues) dendritic cells (DC). Diagnosis is based on clinical presentation, histopathology, and cell markers. The latter is covered extensively on the above website and thus will not be discussed here. Canine cutaneous histiocytoma, which exhibits evidence of Langerhans cell (LC) differentiation, usually occurs as a solitary lesion in young dogs and spontaneously regresses. Cutaneous Langerhans cell histiocytosis (LCH) covers a spectrum of disease, in which multiple cutaneous lesions are consistently observed. In some cases, lymph node and systemic metastasis is also observed. Individual skin lesions otherwise resemble those in histiocytoma. Hence these 2 diseases could be considered part of a larger spectrum of disease with diverse biological behavior. [...]