Abstract
An ultrastructural and histological study was performed to determine the degree of differentiation of the neoplastic cells. The histological study revealed neoplastic cells with pleomorphism, oval nuclei, prominent nucleoli, irregularly distributed chromatin, atypical mitotic figures and moderate amount of cytoplasm containing spherical eosinophilic granulations, typical features of the myeloid lineage. Ultrastructurally, there were cells with an electron-dense, oval and voluminous nucleus, with predominant euchromatin and cytoplasm containing many spherical, electron-dense and homogeneous granules, indicative of myelocytes with differentiation to eosinophils. Type-C viral particles were also seen in the intercellular space of renal tubules and inside the intracytoplasmic vesicles of immature myelocytes in the bone marrow and ovary. PCR was positive to ALV-J.
Highlights
Myeloid leukosis is a neoplastic disease caused by the avian leukosis virus, subgroup J (ALV-J)
There is an exuberant proliferation of immature myelocytes with voluminous nuclei, evident nucleolus and cytoplasm filled with eosinophilic granules and numerous mitoses (Payne and Fadly, 1997)
The cytoplasm contained few to many spherical eosinophilic granules (Fig. 1B)
Summary
Myeloid leukosis is a neoplastic disease caused by the avian leukosis virus, subgroup J (ALV-J). Since ALV-J was firstly reported in the United Kingdom, in 1989 (Payne et al, 1991), there are important studies on the molecular aspects of this virus (Venugopal, 1999; Silva et al, 2000), the pathogenesis of this disease (Stedman et al, 2001), diagnostic methods (Fadly, 2000; Qin et al, 2001) and mode of transmission of viruses (Witter and Fadly, 2001). ALV-J has a tropism for chicken bone marrow cells and induces their neoplastic transformation (Payne, 1992). Myeloid neoplasia arises from primordial haematopoietic cells that originate myeloid lineage cells (erythrocytes, granulated leukocytes, monocytes and thrombocytes). The common aspect in the heterogeneous group of myeloid tumors is the origin from a progenitor cell that normally produces terminal differentiation cells of the myeloid series (Aster and Kumar, 1999)
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