Page 813 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 34 Miscellaneous Tumors 791

alone or in combination with cyclophosphamide (CYC), vincris- tumor in infants and children. 468 Familial cardiac rhabdomyomas
tine (VCR), VCR/CYC, metronomic chemotherapy, ifosfamide, frequently occur in association with tuberous sclerosis complex,
an autosomal dominant disorder caused by mutations in pre-
458–461
dacarbazine, or toceranib phosphate (TOC).
The use of
VetBooks.ir Yunnan Baiyao and epsilon-aminocaproic acid has been evaluated dominantly the TSC2 gene and less frequently the TSC1 gene. 470
for dogs with right atrial masses and pericardial effusion; however,
Infants with cardiac rhabdomyoma often have multifocal lesions
patient outcomes were similar to pericardiocentesis alone. 462 Pre- that arise predominantly in the ventricles; surgical intervention
liminary evidence exists that TOC may mitigate clinical signs for is rarely required as the majority of these lesions will partially or
dogs with heart base tumors, and further investigation into this completely regress with time. 470,471
treatment option is warranted. 463 The role of TOC in the manage- Sarcomas are the most common malignant cardiac tumor, with
ment of heart base tumors in cats is unknown at this time. 341,342 approximately one-third of malignant tumors diagnosed as angio-
Chemotherapy protocols for cats with cardiac or pericardial lym- sarcoma, one-fifth as rhabdomyosarcoma, and with lymphoma
phoma have not been well described, but multiagent protocols being infrequent. 468 More recent reports based on Surveillance,
such as CHOP (combinations of cyclophosphamide [C], doxoru- Epidemiology, and End Results registry data suggest that angio-
bicin [H, hydroxydaunorubicin], vincristine [O, Oncovin], and sarcomas and non-Hodgkin lymphoma (NHL) currently have a
prednisone [P]) or COP (CHOP without the addition of doxoru- similar incidence rate of 0.108 and 0.107 per 10 person-years,
6
bicin) should be considered. 339,412 respectively, with the incidence of NHL steadily increasing over
The role of RT in the management of cardiac tumors has not the study time period (2000–2014). 472 Similar to those in dogs,
yet been well studied. Administration of a single 12 Gy fraction most sarcomas arise from the atria, with the right atrium being
to dogs with right atrial masses and concurrent pericardial effu- more commonly affected than the left. 468,473 Surgical resection is
sion appears to be safe and decreased the frequency of palliative commonly performed; however, the prognosis for primary cardiac
pericardiocentesis. 436 Full-course fractionated RT appears feasible sarcomas treated with surgery alone is poor, with in-hospital post-
and may be beneficial for dogs with heart base masses alone or operative mortality of 22% and MSTs ranging from 9.6 to 20
postoperatively; however, reports are limited to a few cases at this months. 473,474 The benefit of chemotherapy and RT is not well
time. 420,464,465 defined; however, a small study demonstrated that neoadjuvant
DOX/ifosfamide may improve survival of patients with right-
Prognosis sided sarcoma. 475,476
Secondary cardiac tumors predominate in humans, with inci-
The prognosis for cardiac HSA is poor. MSTs for dogs with car- dence rates ranging from 2.3% to 18.3% in autopsy studies. 477
diac HSA treated with surgical resection alone range from 16 days Pericardial metastases are most common, followed by epicardial
to 4 months. 330,332,448,454,457 The addition of DOX-based chemo- and myocardial metastases. Tumors with the highest rate of cardiac
therapy after surgical resection significantly improves survival for metastasis include mesothelioma, melanoma, pulmonary adeno-
dogs with cardiac HSA, with an MST of 175 days when treated carcinoma, undifferentiated carcinoma, and pulmonary squamous
with surgery and adjuvant chemotherapy compared with 42 days cell carcinoma, and breast carcinoma. 477 Tumors that have prefer-
when treated with surgery alone. 332 Dogs with presumptive car- ential cardiac metastasis compared with other sites include mela-
diac HSA treated with DOX-based protocols have a response rate noma, bronchoalveolar carcinoma, and renal carcinoma. 477
of 41%, progression-free survival time of 66 days, and MST of
116 to 140 days. 458,459 Although surgical resection is often not
feasible for dogs with ABT, the prognosis for dogs with ABT is SECTION F: HISTIOCYTIC DISEASES
improved when pericardiectomy is performed with MSTs ranging
from 661 to 730 days. 336,337 Dogs with ABT that do not undergo CRAIG A. CLIFFORD, KATHERINE A. SKORUPSKI
pericardiectomy have significantly worse outcomes, with reported
MSTs ranging from 42 to 129 days. 336,337 Outcomes for other pri- AND PETER F. MOORE
mary cardiac tumors in dogs have not been well studied; however, Background
a number of case reports suggest primary resection of the mass can
result in prolonged survival times. 351,354,364,365 Several well-defined histiocytic proliferative diseases have been
The prognosis for cats with primary cardiac tumors is generally recognized in dogs and cats (Table 34.4). 478 The clinical presenta-
poor. One study evaluating pericardial lymphoma in cats reported tion, behavior, and responsiveness to therapy vary tremendously
an MST of only 9 days; however, one cat treated with a CHOP- between the syndromes observed. The challenge in some instances
based chemotherapy protocol had a survival time of more than is to differentiate them from granulomatous or reactive inflamma-
750 days. 339 tory diseases, or from lymphoma, through examination of regular
paraffin sections. Fortunately, there has been considerable progress
Comparative Aspects in identifying markers that can be used to further characterize cell
lineages in complex leukocytic infiltrates.
Primary tumors of the heart and pericardium are rare in humans;
the majority of cardiac neoplasms are metastatic lesions. Reported Histiocytic Differentiation
incidence of primary cardiac tumors in people range from 0.02%
to 0.056%. 466,467 About 75% of cardiac tumors in humans are The development of canine specific markers for differentiation
benign with myxomas comprising about half of benign tumors in molecules of macrophages and dendritic cells (DCs) has enabled
adults; lipoma, papillary fibroelastoma, and hemangioma occur the identification of the cell lineages involved in canine histiocytic
less commonly. 468 Cardiac myxomas are generally solitary, arise diseases. 479–483 The majority of canine histiocytic diseases involve
from the left ventricle, and surgical resection is the treatment of proliferations of cells of various DC lineages. The term histiocyte
choice. 469 Rhabdomyoma is the most frequent primary cardiac has been used to generically describe cells of DC or macrophage