Page 384 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

362 PART IV Specific Malignancies in the Small Animal Patient

(8%), MCT (7%), giant cell tumor of bone, malignant fibrous Limb function is very good to excellent in most dogs after either
histiocytoma, sarcoma, and melanoma; nonneoplastic masses procedure, regardless of the digit(s) amputated. 172 The roles of RT
Tho-
and chemotherapy remain to be elucidated for the treatment of
167,168
included inflammatory masses, hemangioma, and BCT.
VetBooks.ir racic limb digits may be more commonly affected than pelvic limb malignant digital tumors in the dog and cat. The high metastatic
digits. Multiple digit involvement has been reported in cats with
rate of digital malignant melanoma in dogs clearly suggests that
fibrosarcoma, adenocarcinoma, and SCC. 167,169 Acrometastasis, or adjuvant treatment should be considered.
lung-digit syndrome, is common in cats with primary pulmonary For SCC of the digit treated with surgery alone, 1- and
carcinomas. In a series of 64 cats with digital carcinomas, 88% of 2-year survival rates range from 50% to 83% and 18% to
cats had acrometastasis from primary lung tumors, whereas only 62%, respectively. 161–163 When the tumors are categorized by
13% of cats had primary SCC of the digit. 169 Primary digital SCC the site of origin, dogs with SCC arising from the subungual
and metastatic pulmonary carcinoma were differentiated based on epithelium had a significantly improved survival compared
histopathologic staining characteristics and cell morphology. In with dogs with SCC from other sites on the digit. Dogs with
this series the MSTs of cats with acrometastasis and primary digital a subungual SCC had 1- and 2-year survival rates of 95% and
SCC were 4.9 weeks and 29.5 weeks, respectively. 169 74%, respectively, whereas dogs with SCC at other digital sites
The most common clinical signs in dogs and cats with digital had 60% and 40% 1- and 2-year survival rates, respectively. 161
tumors are the presence of a mass and/or lameness. Digital tumors MSTs for cats with digital SCC ranged from 73 days to 29.5
can metastasize, so appropriate clinical staging is recommended weeks. 167,169
before definitive therapy, including regional LN evaluation and Dogs with digital malignant melanoma have 1- and 2-year
three-view thoracic radiographs or thoracic CT. 161–163,170 Regional survival of 42% to 57% and 13% to 36%, respectively, after
radiographs are recommended to assess for bone involvement treatment with surgery alone. 161–163,170,171 A more recent ret-
because this may have prognostic significance, especially for dogs rospective study that evaluated the effect of carboplatin che-
with digital melanoma. 176 Bone lysis was noted in 80% of dogs motherapy on the survival of dogs with digital melanomas
with digital SCC and in 5% to 100% of dogs with digital mela- treated with surgery found no difference with the inclusion of
noma. 161,163,171 In dogs with digital SCC, 6% to 13% had evidence chemotherapy; these dogs had 1- and 2-year survival rates of
of metastasis at the time of presentation, and an additional 9% to 89% and 67%, respectively, and an MST of 1350 days. 173 In a
17% subsequently developed metastasis. 161,163 A subungual loca- study of 58 dogs treated with an adjuvant xenogenic (murine)
tion may carry a better prognosis than other sites in the digit with tyrosinase vaccine, 174 57 dogs were treated with digital ampu-
digital SCC. 161 In dogs with digital malignant melanoma, 32% to tation, two dogs were treated with RT, and three dogs had
40% had either regional LN or distant metastasis at the time of diag- received adjuvant chemotherapy. Sixteen dogs (28%) had
nosis, and an additional 10% to 26% developed metastatic disease either regional LN or distant metastasis at the time of pre-
after definitive treatment. 161,163 Little information is available on sentation. The overall MST from the time of digital amputa-
cats with primary digital tumors. For cats with digital SCC, three of tion was 476 days, with 1- and 2-year survival rates of 63%
six cats had evidence of bone invasion, one of eight had regional LN and 32%, respectively. Metastatic disease was identified as
metastasis, and none of three had pulmonary metastasis. 169 Among a negative prognostic factor, and distant metastatic disease
cats with digital malignant melanoma, four of five developed metas- was associated with a worse prognosis than metastasis to the
tasis to the regional LN, lung, bone, and/or vertebrae. 168 regional LNs. For five cats diagnosed with digital malignant
The recommended treatment for most cats and dogs with melanoma, survival times ranged from 0 to >577 days, with
digital tumors is digital or partial foot amputation (Fig. 19.6). 163 four cats developing metastatic disease. 168

• Fig. 19.6 Digital melanoma on a dog before digit amputation.