Cutaneous soft tissue tumours in dogs: classification, differentiation, and histogenesis

Area of Science:

• Veterinary Pathology
• Canine Oncology
• Tumor Histopathology

Background:

• Routine morphological examination presents challenges in distinguishing between various canine soft tissue tumors.
• Specific tumors like fibrosarcoma (including myxosarcoma), haemangiopericytoma, and schwannoma are frequently misdiagnosed.
• Accurate histopathological classification is crucial for effective treatment and prognosis in veterinary oncology.

Purpose of the Study:

• To evaluate the diagnostic precision of routine morphological classification for canine soft tissue tumors.
• To investigate the utility of immunohistochemistry in differentiating between fibrosarcoma, haemangiopericytoma, and schwannoma in dogs.
• To propose a more accurate terminology for a group of canine spindle cell tumors.

Main Methods:

• Immunohistochemical examination of 74 canine soft tissue tumors.
• Tumors were initially classified using routine light microscopy.
• Comparative analysis of morphological and immunohistochemical findings.

Main Results:

• Routine morphological diagnosis of canine cutaneous fibrosarcoma, haemangiopericytoma, or schwannoma showed limited precision.
• Immunohistochemistry provided more detailed differentiation of tumor cell types.
• Significant overlap in morphological features was observed among these tumor types.

Conclusions:

• The term 'fibrosarcoma' (including myxosarcoma), 'haemangiopericytoma', and 'schwannoma' lack diagnostic precision for canine soft tissue tumors based on morphology alone.
• Immunohistochemistry is a valuable tool for improving the accuracy of canine soft tissue tumor classification.
• A unified diagnostic term, 'spindle cell tumor of canine soft tissue', is proposed to encompass this group of lesions, reflecting their shared characteristics and diagnostic challenges.