Cutaneous Reactive Histiocytosis in Golden Retrievers: An Immunohistochemical Approach

BACKGROUND: Canine cutaneous reactive histiocytosis (CRH) is a proliferative histiocytic disease characterised by the accumulation of dendritic cells (DCs). Differentiating CRH from other infectious or non-infectious granulomatous or histiocyte-rich diseases is challenging on histological evidence alone. HYPOTHESIS/OBJECTIVES: This study aims to characterise the predominant histiocytic population in 11 golden retrievers with histological features compatible with CRH, using ionised calcium-binding adapter molecule 1 (Iba1) and a validated macrophage antibodies cocktail for canine skin diseases. ANIMALS: Eleven golden retriever dogs were enrolled with a clinical and histological diagnosis of CRH. MATERIALS AND METHODS: Paraffin-embedded skin biopsy samples from cases with a confirmed diagnosis of CRH were evaluated to identify the histiocytic cell type. Two antibody reagents were used: (1) anti-Iba1 (goat polyclonal), a broad histiocytic marker and (2) a cocktail of rabbit recombinant monoclonal antibodies against CD11b, CD68, CD163, CD14 and CD16 to phenotype cutaneous macrophages. RESULTS: All cases showed positive immunostaining with both antibodies. Although Iba1 immunostaining was diffuse in most of the histiocytoid cell population, only a few scattered histiocytoid cells stained with the anti-macrophage antibody cocktail. CONCLUSION AND CLINICAL RELEVANCE: Strong Iba1 positivity in the histiocytoid cells, together with their lack of staining for macrophage markers, supports a dendritic cell phenotype and is consistent with a diagnosis of CRH. In conclusion, using a macrophage marker in combination with a broad histiocytic marker may help to distinguish CRH from granulomatous, macrophage-rich diseases in paraffin-embedded skin tissue.

Authors: F. Albanese, G. Lazzarini, M. Orlandi, A. Pirone, V. Miragliotta, E. Mazzoni, L. Pazzini, M. Massaro, L. Aresu and F. Abramo Title: Cutaneous Reactive Histiocytosis in Golden Retrievers: An Immunohistochemical Approach Full source: Vet Dermatol, 2026,Vol Document type: Journal Article
Résumé, analyse et commentaires
Aucun.
Photo
Aucune.
Analysis
None.
Abstract	Source
BACKGROUND: Canine cutaneous reactive histiocytosis (CRH) is a proliferative histiocytic disease characterised by the accumulation of dendritic cells (DCs). Differentiating CRH from other infectious or non-infectious granulomatous or histiocyte-rich diseases is challenging on histological evidence alone. HYPOTHESIS/OBJECTIVES: This study aims to characterise the predominant histiocytic population in 11 golden retrievers with histological features compatible with CRH, using ionised calcium-binding adapter molecule 1 (Iba1) and a validated macrophage antibodies cocktail for canine skin diseases. ANIMALS: Eleven golden retriever dogs were enrolled with a clinical and histological diagnosis of CRH. MATERIALS AND METHODS: Paraffin-embedded skin biopsy samples from cases with a confirmed diagnosis of CRH were evaluated to identify the histiocytic cell type. Two antibody reagents were used: (1) anti-Iba1 (goat polyclonal), a broad histiocytic marker and (2) a cocktail of rabbit recombinant monoclonal antibodies against CD11b, CD68, CD163, CD14 and CD16 to phenotype cutaneous macrophages. RESULTS: All cases showed positive immunostaining with both antibodies. Although Iba1 immunostaining was diffuse in most of the histiocytoid cell population, only a few scattered histiocytoid cells stained with the anti-macrophage antibody cocktail. CONCLUSION AND CLINICAL RELEVANCE: Strong Iba1 positivity in the histiocytoid cells, together with their lack of staining for macrophage markers, supports a dendritic cell phenotype and is consistent with a diagnosis of CRH. In conclusion, using a macrophage marker in combination with a broad histiocytic marker may help to distinguish CRH from granulomatous, macrophage-rich diseases in paraffin-embedded skin tissue.