Granular cell tumour in an endangered Puerto Rican Amazon parrot (Amazon vittata )

Area of Science:

• Veterinary Pathology
• Avian Medicine
• Comparative Oncology

Background:

• Granular cell tumors (GCTs) are rare neoplasms typically found in mammals.
• GCTs are characterized by cells containing abundant eosinophilic granules.
• The histogenesis of GCTs remains incompletely understood, with various cell types proposed as their origin.

Purpose of the Study:

• To report and characterize a rare case of granular cell tumor in a bird.
• To investigate the ultrastructural features of the avian GCT.
• To contribute to the understanding of GCTs in non-mammalian species.

Main Methods:

• Gross examination and light microscopy of a metacarpal mass.
• Histochemical staining, including Periodic Acid-Schiff (PAS) and diastase digestion.
• Transmission electron microscopy (TEM) for ultrastructural analysis.

Main Results:

• A 3 cm diameter mass was diagnosed as a granular cell tumor.
• Cytoplasmic granules were PAS positive and diastase resistant.
• Ultrastructural analysis revealed convoluted nuclei and numerous cytoplasmic tertiary lysosomes.

Conclusions:

• This represents only the second reported case of a granular cell tumor in a bird.
• The findings support the hypothesis that GCTs may arise from cells involved in degradative processes.
• Further research is needed to elucidate the uniform histogenesis of granular cell tumors across species.