Interpretive Discussion
The hemogram reveals a monocytosis and an elevated
plasma protein (normal plasma protein values
using the biuret method for most snakes is less than 8
g/dL). This suggests an inflammatory response; however,
a monocytosis without a coexisting leukocytosis
and heterophilia is unusual. The monocytosis is likely associated with mobilization of monocytes because of
peripheral demand for macrophages. Perhaps other cells
were misidentified as monocytes because of their unusual
morphology, such as toxic heterophils, if present.
A blood film in this case, however, was not available for
review.
Figures 76.2a–76.2c show mesenchymal cells, with
basophilic cytoplasm often containing fine eosinophilic
granules. These cells are embedded in an eosinophilic
background material. The nuclei are frequently positioned
at one edge of the cell and have coarsely
granular chromatin with occasional prominent nucleoli.
The cells exhibit moderate anisocytosis and variable
nucleus–cytoplasm ratios. The cytologic examination
indicates a mesenchymal cell neoplasm that is
producing either chondroid or osteoid, therefore, likely
has its origins in cartilage or bone. A chondroma or chondrosarcoma is more likely than an osteogenic sarcoma,
owing to the lack of cells having the typical appearance
of osteoblasts.
Summary
The snake died before it could be prepared for surgical
removal of the tracheal mass. The plan was to
remove the mass by transection of the involved section of the trachea followed by anastomosis of the healthy
tracheal ends.
The gross necropsy revealed a 1 cm white glistening
intratracheal mass occluding the lumen. Histopathologic
findings revealed an increased number of normalappearing
chondrocytes within lacunae in a disorganized
chondroid matrix. Mitotic figures were rare. The mass
was focally continuous with the mineralized cartilaginous
ring indicating that it arose from the tracheal ring.
The diagnosis was a benign chondroma of the trachea.