Page 166 - Differential Diagnosis in Small Animal Cytology, The Skin and Subcutis

Mesenchymal Tumours and Other Neoplasms
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• Alveolar rhabdomyosarcoma:
• Uncommon form, mostly observed in young dogs.
VetBooks.ir • It presents as mass lesion in various sites.
Cells may be individualized or forming poorly cohesive groups.
•
• Aspirates exfoliate variable numbers of round to oval cells with a high N:C ratio and variably
defined margins. The cytoplasm is scant to moderate and can contain small clear punctate
vacuoles.
• Occasionally, the individual cell morphology may resemble large lymphoid cells.
• Anisokaryosis and anisocytosis are moderate.
• Mitotic figures can be frequent.
• Pleomorphic rhabdomyosarcoma:
• Very uncommon form, only rarely reported in dogs and cats and mostly in the larger
muscles of the limbs.
• In practice, it can be difficult to differentiate pleomorphic rhabdomyosarcoma from embry-
onal and alveolar types, as they may look similar. Cells often shown marked features of atypia.

Differential diagnoses
• Soft tissue sarcoma of other origin
• Histiocytic sarcoma
• Round cell tumour:
• Extramedullary plasmacytoma
• Lymphoma

Fig. 9.21. Dog. Embryonal rhabdomyosarcoma. Wright-Giemsa. (Courtesy of Giancarlo Avallone, University of
Bologna, Italy.)