Cutaneous Reactive Histiocytosis in Golden Retrievers: An Immunohistochemical Approach

Area of Science:

• Veterinary Dermatology
• Immunohistochemistry
• Canine Pathology

Background:

• Canine cutaneous reactive histiocytosis (CRH) is a proliferative disease involving dendritic cells (DCs).
• Histological differentiation of CRH from other histiocyte-rich skin conditions can be challenging.
• Accurate diagnosis is crucial for effective treatment of canine skin diseases.

Purpose of the Study:

• To characterize the predominant histiocytic cell population in canine CRH cases.
• To utilize ionised calcium-binding adapter molecule 1 (Iba1) and macrophage antibodies for phenotyping.
• To improve diagnostic accuracy for CRH in canine skin biopsies.

Main Methods:

• Eleven Golden Retrievers with clinical and histological CRH diagnoses were studied.
• Skin biopsy samples were analyzed using immunohistochemistry.
• Antibodies used included anti-Iba1 (broad histiocytic marker) and a macrophage cocktail (CD11b, CD68, CD163, CD14, CD16).

Main Results:

• All CRH cases showed positive Iba1 immunostaining in histiocytoid cells.
• A few scattered cells stained positive for the macrophage antibody cocktail.
• Iba1 staining was diffuse, while macrophage marker staining was limited.

Conclusions:

• Strong Iba1 positivity and lack of macrophage marker staining support a dendritic cell phenotype in CRH.
• This immunophenotype is consistent with a diagnosis of canine cutaneous reactive histiocytosis.
• Combining broad histiocytic and macrophage markers aids in distinguishing CRH from other granulomatous skin diseases.