Hepatic B-Cell Lymphoma in a Common Mynah (Acridotheres tristis): A Case Report.

Abstract

Background: Hepatic lymphoma is rarely characterized in mynah birds, and severe hepatomegaly in this group is often interpreted in relation to iron storage disease or other metabolic hepatopathies.

Case description: This report describes hepatic B-cell lymphoma in a 14-year-old common mynah (Acridotheres tristis) presented with lethargy, altered vocalization, poor body condition, ascites, dyspnea, chronic ataxia, and left-leg lameness. Radiography revealed a large soft-tissue opacity in the middle coelomic cavity, with caudodorsal displacement of the intestinal loops and compression of the thoracoabdominal air sacs. Ultrasonography identified a very large hepatic mass with granular and mixed echogenicity occupying most of the coelomic cavity. The bird was euthanized at the owner's request because of the severity of the lesion and poor clinical condition. At necropsy, the liver was markedly enlarged, dark red to reddish-brown, mottled and occupied most of the coelomic cavity. Histologically, the hepatic parenchyma was extensively replaced by densely packed mononuclear neoplastic cells, with effacement of hepatic cords and hepatocellular necrosis. No neoplastic infiltration was identified in the examined tissues, including spleen, kidney, intestine, lung, and heart; therefore, the liver was the only confirmed site of lymphoma among the examined tissues in this case. An immunohistochemical and histochemical panel including CD3, CD79α/MB-1, CD20, lysozyme, CD68, alpha-1-antitrypsin, toluidine blue, and Giemsa staining was applied to characterize the tumor lineage and exclude other round-cell neoplasms. Neoplastic cells showed diffuse cytoplasmic immunoreactivity for CD79α/MB-1 and lacked evidence of T-cell, monocyte/macrophage, or mast cell differentiation, supporting a diagnosis of hepatic B-cell lymphoma.

Conclusion: This case highlights the need for tissue-based diagnosis in mynah birds with marked hepatomegaly and demonstrates the value of integrating diagnostic imaging, histopathology, immunohistochemistry, and molecular testing in avian hepatic round-cell tumors.