Cutaneous Reactive Histiocytosis in Golden Retrievers: An Immunohistochemical Approach.

Combined Iba1 and macrophage antibodies reliably differentiate CRH from granulomatous diseases.

Canine cutaneous reactive histiocytosis (CRH) is a proliferative histiocytic disease characterized by dendritic cell accumulation that is difficult to distinguish from other granulomatous or histiocyte-rich diseases using histology alone. This study evaluated 11 golden retrievers with CRH using immunohistochemical markers to characterize the predominant histiocytic population. Researchers employed Iba1 (ionised calcium-binding adapter molecule 1), a broad histiocytic marker, and a validated macrophage antibody cocktail targeting CD11b, CD68, CD163, CD14, and CD16. All cases demonstrated positive Iba1 immunostaining across most histiocytoid cells, but only scattered cells stained positive with the macrophage antibody cocktail. The strong Iba1 positivity combined with minimal macrophage marker expression supports a dendritic cell phenotype, confirming CRH diagnosis. This immunohistochemical approach effectively differentiates CRH from macrophage-rich granulomatous diseases in paraffin-embedded skin tissue samples, providing veterinary dermatologists with a practical diagnostic tool for accurate disease classification and differentiation.

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