In the period 1993-1998, digital carcinomas in 64 cats were examined. In al
l animals primary complaints were painful digit(s), Eight cats had a primar
y squamous cell carcinoma which involved one digit or two adjacent digits o
f one leg. Fifty-six cats had metastases of a pulmonary carcinoma in the di
gits, and in general multiple digits of different legs were involved. In ma
ny of these cats metastases also occurred in other organs, including the sk
in and muscles. No primary sweat gland carcinomas of the digits were seen.
Primary squamous cell carcinomas of the digits were characterized by cornif
ication and the absence of PAS-positive cells, PAS-positive secretory mater
ial. Immunohistochemically, these neoplasms stained negative with the monoc
lonal antibody CAM 5.2 directed against Keratin 8 (K 8), The metastases of
pulmonary carcinomas to the digits showed one or more of the following hist
ological features: goblet cells, ciliated epithelial cells, PAS-positive ce
lls or lakes, and/or a PAS-positive lining of luminal membranes and no corn
ification. Immunohistochemically, they showed positive staining for CAM 5.2
(K8),
Thoracic radiographs from three cats with a primary squamous cell carcinoma
showed no abnormalities, whereas all cases of metastases from a pulmonary
carcinoma to the digits available for follow-up showed evidence of a primar
y pulmonary carcinoma on radiography and/or postmortem examination (25 out
of 56),
The conclusion of this study was that most carcinomas in the digits of cats
were metastases of a primary pulmonary carcinoma (87.5%), Primary squamous
cell carcinomas occurred infrequently. The prognosis of metastases of a pu
lmonary carcinoma in the digits is poor with an average survival time of 4.
9 weeks, in contrast to 29.5 weeks in cats with a squamous cell carcinoma.
These data stress the importance of taking thoracic radiographs of cats wit
h digital tumours before surgical intervention.