chapter 25 Histiocytic Proliferative Disorders...........................
DEFINITION/OVERVIEW
Disorders resulting from proliferation of cells from the monocyte/macrophage lin-
eage, Langerhans cells of the skin and dendritic cells (“antigen-presenting cells” of
the lymph nodes, thymus, and spleen).Histiocytic proliferative disorders include both neoplastic and nonneoplastic (reactive
inflammatory granulomatous disorders secondary to dysregulation of proliferation)
disorders.Includes cutaneous histiocytoma, reactive histiocytosis (reactive cutaneous histi-
ocytosis, reactive systemic histiocytosis), histiocytic sarcoma (localized histiocytic
sarcoma, disseminated histiocytic sarcoma, malignant histiocytosis), and malignant
fibrous histiocytoma.Organ systems affected include skin, hemic/lymphatic, nervous, ophthalmic, and
respiratory.
Reactive histiocytoses occur in dogs; feline progressive histiocytosis is reported.
ETIOLOGY/PATHOPHYSIOLOGY
Cutaneous histiocytoma:
Common benign neoplasm of the dog
Considered reactive hyperplasia rather than true neoplasm
Langerhans cell is the proliferating cell
Categorized as an epidermotropic Langerhans cell histiocytosis.
Reactive cutaneous histiocytosis:
Dysregulation of dendritic “antigen-presenting” cells producing a benign reac-
tive perivascular proliferation
Single or multiple nodules
Infiltration of skin and subcutaneous tissue
May wax and wane over years.Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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