Peritoneal effusion in a dog secondary to visceral mast cell tumor. A case report.
BACKGROUND
Mast cell tumor, one of the most common skin tumors in dogs, may also be found in visceral sites (mainly spleen and liver). When a visceral mast cell tumor is present, neoplastic mast cells may be found in any effusion secondary to the tumor. Therefore, the diagnosis may be made by cytologic analysis of the effusion.


METHODS
An 8-year-old, spayed, female Siberian husky presented with a peritoneal effusion secondary to a visceral mast cell tumor. Seven months earlier, the dog had presented with a cutaneous nodule diagnosed as a well-differentiated mast cell tumor. The peritoneal fluid was classified as a transudate. Numerous neoplastic mast cells were found in the effusion. Although the mast cell tumor presented with characteristics of the well-differentiated tumor, its biologic behavior was that of a malignant tumor.


CONCLUSIONS
Care should be taken to evaluate the prognosis of mast cell tumors in dogs since their biologic behavior is extremely variable.
de Souza
M L
ML
Departments of Clinics and of Animal Reproduction and Radiology, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil.
Torres
L F
LF
Rocha
N S
NS
Takahira
R K
RK
Mamprim
M J
MJ
Burini
C H
CH
Bandarra
E P
EP
Figueiredo
L M
LM
D000008:Abdominal Neoplasms / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D001202:Ascitic Fluid / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D012515:Mast-Cell Sarcoma / Q000473:pathology / Q000662:veterinary*