Page 1289 - Small Animal Internal Medicine, 6th Edition

CHAPTER 74 Cytology 1261

VetBooks.ir

FIG 74.4 FIG 74.6
Photomicrograph of pleural fluid from an older female Photomicrograph of a fine-needle aspirate of a firm,
Irish Setter showing a cluster of deeply basophilic cells, lobulated, subcutaneous mass in an older dog. The cells are
with vacuolated cytoplasm, anisocytosis, anisokaryosis, spindle-shaped, have “tails,” and do not associate with
and prominent nucleoli. The cytologic diagnosis was other cells. The nuclei appear to be protruding from the
carcinomatosis (i.e., metastatic adenocarcinoma of unknown cytoplasm (×1000). The cytologic diagnosis is spindle cell
origin) (×1000). sarcoma. Histopathologic findings were diagnostic for
fibrosarcoma.

FIG 74.7
Photomicrograph of one of several purple cutaneous nodules
in a dog with a primary splenic hemangiosarcoma. The
FIG 74.5 polygonal to spindle-shaped cells with blue-gray cytoplasm
Photomicrograph of a fine-needle aspirate of a firm, and vacuoles are characteristic of hemangiosarcoma (the
lobulated, subcutaneous mass in an older dog. The cells lesions were metastases from the primary tumor) (×1000).
appear to be in clusters, but closer inspection reveals that it (Courtesy Dr. S. M. Nguyen.)
is an aggregate of spindle cells consistent with spindle cell
sarcoma. The clinical diagnosis was hemangiopericytoma
(×500). and minimal discomfort to the patient. Multinucleated giant
cells are common in some sarcomas in cats.
As discussed earlier, because sarcoma cells usually do not
cells in most sarcomas tend to form “tails,” and the nuclei exfoliate well, aspirates may yield false-negative results.
protrude from the cytoplasm (Fig. 74.6). The presence of Therefore, if a mass is clinically suspected to be a sarcoma
spindle-shaped or polygonal cells with a vacuolated blue-gray and FNA findings are negative, a core biopsy specimen of the
cytoplasm is highly suggestive of hemangiosarcoma (Fig. mass should be obtained because it is likely to be a sarcoma.
74.7). Intercellular matrix (e.g., osteoid, chondroid) is found
occasionally in osteosarcomas (OSAs) and chondrosarcomas Round (Discrete) Cell Tumors
(CSAs), respectively; in these two tumor types the cells are Tumors composed of a homogeneous population of round
usually round or ovoid. The preferred approach to lytic bone (or discrete) cells are referred to as round (or discrete) cell
lesions in our clinics is to perform an FNA (see Chapter 81); tumors (RCTs). These tumors are common in dogs and cats
the probability of obtaining a definitive diagnosis is higher and include lymphoma (LSA), histiocytoma (HCT), MCT,
than when doing a bone biopsy, with significantly lower cost, transmissible venereal tumor (TVT), plasma cell tumor