Primary cardiac histiocytic sarcoma in a dog

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Primary cardiac histiocytic sarcoma (n=1). Intervention: Immunohistochemistry with Iba1, HLA-DR, CD204, CD3, and CD20 antibodies and necropsy examination. Primary outcome: Histopathological and immunohistochemical characterization of cardiac nodules and pulmonary metastasis.

Q: What does this research mean for the field?

Histiocytic sarcoma can arise primarily in the canine heart with diffuse immunoreactivity for Iba1 and HLA-DR and early microscopic pulmonary metastasis. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

N. V. Giang; Nguyen Thi Trang; Naoyuki Fuke; Takuya Hirai; Ryoji Yamaguchi

doi:10.1292/jvms.26-0228

January 1, 2026Journal of Veterinary Medical ScienceOpen Access

Primary cardiac histiocytic sarcoma in a dog

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Key result

Canine primary cardiac histiocytic sarcoma demonstrates diffuse Iba1 and HLA-DR immunoreactivity with pulmonary metastasis.

n=1

Key Points

To describe the clinical, pathological, and immunohistochemical features of a rare primary cardiac histiocytic sarcoma with pulmonary metastasis in a dog.
A 14-year-old intact male mixed-breed dog presented with anorexia and depression underwent ultrasound, tomography, echocardiography, and postmortem examination.
Tissue samples from cardiac masses (n=12) and the lungs (n=3) were fixed in 10% neutral buffered formalin and stained with hematoxylin and eosin.
Immunohistochemical analysis was performed on paraffin-embedded cardiac and lung sections using antibodies against HLA-DR, Iba1, CD204, CD3, and CD20.
Necropsy revealed multiple yellow-to-whitish nodules ranging from a few millimeters to 1.5 cm in diameter in the heart muscle, with no gross lesions detected in other organs.
Microscopic analysis of the heart identified pleomorphic round-to-oval and multinucleated cells that stained diffusely positive for Iba1 and HLA-DR, but negative for CD204.
Histological and immunohistochemical examination of lung tissue identified metastatic Iba1- and HLA-DR-positive neoplastic cells inside and around blood vessels, despite normal macroscopic lung appearance.

Study Design

Type

Case Report (n=1)

Multicenter

No

Structured PICO

P

Population

A 14-year-old intact male mixed-breed dog (10.4 kg) with primary cardiac histiocytic sarcoma presenting with anorexia and depression, followed for 1 week until death from cardiac arrest.

E

Exposure

Supportive treatment with vitamins and dopamine prior to death; post-mortem necropsy, routine hematoxylin and eosin (HE) histological examination, and immunohistochemistry (HLA-DR, Iba1, CD204, CD3, CD20) on cardiac (n=12) and lung (n=3) tissue samples.

O

Outcome

Histological and immunophenotypic characterization of primary cardiac histiocytic sarcoma.

This case report documents a rare pathological presentation of primary cardiac histiocytic sarcoma predominantly involving the myocardium with microscopic pulmonary metastasis in a dog, expanding the anatomical and immunohistochemical spectrum of canine histiocytic sarcoma.

Limitations

Single case report (n=1)
Available histological sections did not allow determination of whether multinodular cardiac lesions represented intramyocardial extension/satellite formation from a single primary focus or multifocal lesions within the myocardium
Available histological sections did not allow determination of whether the multinodular cardiac lesions represented intramyocardial extension or satellite formation from a single primary focus, or multifocal lesions within the myocardium.

Implication

May aid differential diagnosis of canine myocardial masses; extends the documented IHC profile and occult metastatic behavior of histiocytic sarcoma.

Abstract

An intact male mixed-breed dog was presented with anorexia and depression. Ultrasonographic examination did not reveal any nodules in the thoracic or abdominal organs. However, several nodules of different sizes were identified in the heart at necropsy, with no gross lesions detected in other organs. Histological examination of the cardiac tissues revealed an accumulation of pleomorphic, round-to-oval phagocytic cells, suggestive of histiocytic origin, which was subsequently confirmed by immunohistochemistry with specific histiocytic antibodies (Iba1 and HLA-DR). Although no gross nodules were observed in the lungs, histologic examination revealed scattered neoplastic cells, indicating metastasis from the primary cardiac lesion. This case represents a rare pathological presentation of primary cardiac histiocytic sarcoma in a dog, expanding the documented anatomical and pathological spectrum of canine histiocytic sarcoma.

Discussion

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Cite This Study

Giang et al. (2026) conducted a case report in Primary cardiac histiocytic sarcoma (n=1). Immunohistochemistry with Iba1, HLA-DR, CD204, CD3, and CD20 antibodies and necropsy examination was evaluated on Histopathological and immunohistochemical characterization of cardiac nodules and pulmonary metastasis. Primary cardiac histiocytic sarcoma in a 14-year-old dog demonstrated diffuse immunoreactivity for Iba1 and HLA-DR, negativity for CD204, and microscopic pulmonary metastasis at necropsy.

synapsesocial.com/papers/6ae224a51d5c3b3dd394b08d https://doi.org/10.1292/jvms.26-0228

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Primary cardiac histiocytic sarcoma in a dog

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Primary cardiac histiocytic sarcoma in a dog

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

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