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Updated: Sep 26, 2026
Multiplexed Fluorescent Immunohistochemical Staining, Imaging, and Analysis in Histological Samples of Lymphoma
Published on: January 9, 2019
Cytology of canine malignant histiocytosis
Diane E. Brown1, Mary Anna Thrall, David M. Getzy
1Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado Sate University, Fort Collins, CO 80523.
Insights
Lysozyme immunohistochemistry aids in diagnosing canine malignant histiocytosis. This diagnostic tool identifies neoplastic cells in cytology and tissue samples, crucial for this aggressive cancer.
Area of Science:
- Veterinary Pathology
- Canine Oncology
- Cytopathology
Background:
- Malignant histiocytosis is an aggressive neoplastic disease in dogs.
- Accurate diagnosis is essential for prognosis and treatment.
Purpose of the Study:
- To describe the cytologic features of malignant histiocytosis in dogs.
- To evaluate the utility of lysozyme immunohistochemistry for diagnosis.
Main Methods:
- Review of seven canine cases with malignant histiocytosis.
- Analysis of bone marrow, tissue, and abdominal fluid cytology.
- Histopathology, hematology, serum biochemistry, and immunohistochemistry.
Main Results:
- Neoplastic cells showed positive immunoreactivity to lysozyme.
- Cytologic findings included pleomorphic mononuclear cells, anisocytosis, anisokaryosis, and prominent nucleoli.
- Hematologic abnormalities included anemia and thrombocytopenia; hypercalcemia was also observed.
Conclusions:
- Lysozyme immunohistochemistry is a reliable method for diagnosing canine malignant histiocytosis.
- Cytologic features are characteristic and aid in diagnosis.
- Early and accurate diagnosis is critical for affected dogs.
Abstract:
Cytologic features of bone marrow, tissue, and abdominal fluid in seven cases of malignant histiocytosis in dogs are described, and histopathology, hematology, and serum biochemistry of the cases are reviewed. Diagnosis of malignant histiocytosis was confirmed by tissue morphology and immunohistochemistry; neoplastic cells in all cases had positive immunoreactivity to lysozyme. This stain can be used to definitively establish the diagnosis of malignant histiocytosis on cytology specimens as well as tissue sections. Cytologic findings included numerous pleomorphic, large, discrete mononuclear cells with abundant, lightly basophilic, vacuolated, granular cytoplasm. Nuclei were round to oval to reniform with marked anisocytosis and anisokaryosis; nucleoli were prominent. Mitotic figures, often bizarre, were occasionally seen. Multinucleated giant cells and phagocytosis of erythrocytes and leukocytes were prominent features in cytologic preparations in four cases. Four dogs were anemic, five dogs were thrombocytopenic, and three dogs were hypercalcemic. Breeds affected included Doberman Pinscher (1), Golden Retriever (2), Flat Coated Retriever (3), and mixed-breed dog (1).
