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Below is a cache of http://www.avianmedicine.net/ampa/25.pdf. It's a snapshot of the page taken as our search engine crawled the Web.
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content. Avian Medicine: Princilpes and Application eoplasia is an abnormal, uncontrolled, pro-
gressive proliferation of cells in any tissue
or organ. Classification of neoplasms is
based upon general tissue origin (epithelial vs. mesenchymal), specific cell lineage and whether
the neoplasm is benign (-oma) or malignant (sarcoma
or carcinoma). Classification of some neoplasms as
benign or malignant may require knowledge of the
biological behavior of the neoplasm. The majority of the veterinary medical literature has
reported the incidence, gross appearance and micro-
scopic characteristics of neoplasms of domesticated
birds, especially poultry. 20,22,23,101,109 Furthermore, the study of retroviral-induced neoplasia in poultry has
advanced medical knowledge of retroviral molecular
biology, as well as that of neoplasm development,
growth and metastasis. 91,101 Similar information con- cerning neoplasms of captive and free-ranging birds
is almost nonexistent. One ultrastructural survey of
various budgerigar neoplasms failed to disclose
retroviral particles, but sampling errors are a known
complication of such studies. 52 More recently, papil- lomaviruses have been demonstrated as the etiologic
agents of cutaneous papillomas in African Grey Par-
rots, Chaffinches and Bramblings. 73,87,94,96 Reports of neoplasia are extant for captive as op-
posed to free-ranging birds, 5,6,7,12,15,49,51,83,102,108 espe- cially budgerigars, where the overall incidence of
neoplasia ranges from 16.8% to 24.2%. 12,15,51 In a veterinary diagnostic laboratory with a diverse avian
caseload, budgerigars accounted for 69.7% of all psit-
tacine neoplasms and 41% of all avian neoplasms
recorded. The overall incidence of neoplasia approxi-
mated 3.8% in all avian submissions. 108 Compared to free-ranging birds, neoplasia is re-
ported more frequently in companion and aviary
birds because such birds are observed closely for
abnormalities, have a longer life span and may have
a genetic predisposition to neoplasia through in-
breeding. Little is known, however, concerning the
etiology, predisposing factors, development, biologi-
cal behavior or treatment of neoplasms in companion
and aviary birds. As more cases of avian neoplasia
are studied and reported, our clinicopathologic
knowledge will increase and treatment regimens will
improve. N C H A P T E R 25 O NCOLOGY Kenneth S. Latimer This chapter is written to provide a systems ap-
proach to avian neoplasia, with an emphasis on neo-
plasms of companion, aviary and free-ranging birds.
Information is presented to assist the clinician in
understanding the complexities and treatment of
avian neoplasms (see Table 25.1). Lesions that mimic
neoplasia also are discussed briefly. Lastly, the cy-
tologic and histologic features of various neoplasms
are presented to assist veterinary pathologists in the
diagnosis of these neoplasms (see Table 25.2). Integumentary System Neoplasms of the integumentary system are common
and account for 12% to 70% of all avian neo-
plasms. 6,12,15,108 Of the various neoplasms reported, lipomas and fibrosarcomas are observed most fre-
quently. Adipose Neoplasms and Masses Neoplasms associated with fatty tissue and lipid
deposition in companion birds include lipoma,
myelolipoma, liposarcoma and hibernoma. Lesions
that mimic these neoplasms include xanthomas and
lipogranulomas. Definitive diagnosis of each of these
neoplasms or masses requires histopathologic exami-
nation of surgical biopsy specimens (Figure 25.1). Lipoma: Lipomas are benign proliferations of well differentiated adipocytes (lipocytes) that may exhibit
slow-to-rapid, progressive growth over time. Lipomas
are the most frequently observed neoplasm of com-
panion birds, with a reported incidence of 10% to 40%
in budgerigars. 143 Besides budgerigars, lipomas may be observed frequently in Rose-breasted Cockatoos
(galahs) and Amazon parrots. 98,143 Obesity, advancing age, species of bird and high-energy diets appear to
be predisposing factors for tumor development.
Based upon clinical observations, a genetic predispo-
sition to lipoma development may exist in budgeri-
gars. Lipomas usually arise in the subcutis of the sternal
or abdominal skin, but may also be observed on the
wings, back, neck, legs or near the uropygial
gland. 6,12,15,30,49,51,69,72,86,102,108,127 In addition, lipomas may occur in the thoracoabdominal cavity (arising
from thoracic or mesenteric fat, ovary, ventriculus
and liver) or in association with skeletal mus- cle. 12,40,102,108,127 Tumor size typically ranges from 0.3 to 4.0 cm in diameter (Color 25.2). Lipomas occur as single or multiple masses. Affected
birds may be presented for diagnosis of a visible skin
or subcutaneous mass or abdominal distention.
Large tumors may interfere with leg movement,
perching or flight. On palpation, lipomas are usually
well defined and soft; the overlying skin is freely
mobile. 143 Grossly, excised lipomas appear soft, round-to-mul-
tilobulated and pale yellow. On cut surface, they are
thinly encapsulated and fatty. Histologically, lipomas
appear as thinly encapsulated masses composed of
lobules of well differentiated adipocytes. Scattered FIG 25.1 A 15-year-old Amazon parrot was referred for evaluation
of a tumor. A previous veterinarian had advised euthanasia. A
large, pendulated, ulcerative mass was present on physical exami-
nation. The bird was in overall good condition, and abnormal
clinicopathologic findings were limited to a mild heterophilia
(18,000/
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content. Avian Medicine: Princilpes and Application eoplasia is an abnormal, uncontrolled, pro-
gressive proliferation of cells in any tissue
or organ. Classification of neoplasms is
based upon general tissue origin (epithelial vs. mesenchymal), specific cell lineage and whether
the neoplasm is benign (-oma) or malignant (sarcoma
or carcinoma). Classification of some neoplasms as
benign or malignant may require knowledge of the
biological behavior of the neoplasm. The majority of the veterinary medical literature has
reported the incidence, gross appearance and micro-
scopic characteristics of neoplasms of domesticated
birds, especially poultry. 20,22,23,101,109 Furthermore, the study of retroviral-induced neoplasia in poultry has
advanced medical knowledge of retroviral molecular
biology, as well as that of neoplasm development,
growth and metastasis. 91,101 Similar information con- cerning neoplasms of captive and free-ranging birds
is almost nonexistent. One ultrastructural survey of
various budgerigar neoplasms failed to disclose
retroviral particles, but sampling errors are a known
complication of such studies. 52 More recently, papil- lomaviruses have been demonstrated as the etiologic
agents of cutaneous papillomas in African Grey Par-
rots, Chaffinches and Bramblings. 73,87,94,96 Reports of neoplasia are extant for captive as op-
posed to free-ranging birds, 5,6,7,12,15,49,51,83,102,108 espe- cially budgerigars, where the overall incidence of
neoplasia ranges from 16.8% to 24.2%. 12,15,51 In a veterinary diagnostic laboratory with a diverse avian
caseload, budgerigars accounted for 69.7% of all psit-
tacine neoplasms and 41% of all avian neoplasms
recorded. The overall incidence of neoplasia approxi-
mated 3.8% in all avian submissions. 108 Compared to free-ranging birds, neoplasia is re-
ported more frequently in companion and aviary
birds because such birds are observed closely for
abnormalities, have a longer life span and may have
a genetic predisposition to neoplasia through in-
breeding. Little is known, however, concerning the
etiology, predisposing factors, development, biologi-
cal behavior or treatment of neoplasms in companion
and aviary birds. As more cases of avian neoplasia
are studied and reported, our clinicopathologic
knowledge will increase and treatment regimens will
improve. N C H A P T E R 25 O NCOLOGY Kenneth S. Latimer This chapter is written to provide a systems ap-
proach to avian neoplasia, with an emphasis on neo-
plasms of companion, aviary and free-ranging birds.
Information is presented to assist the clinician in
understanding the complexities and treatment of
avian neoplasms (see Table 25.1). Lesions that mimic
neoplasia also are discussed briefly. Lastly, the cy-
tologic and histologic features of various neoplasms
are presented to assist veterinary pathologists in the
diagnosis of these neoplasms (see Table 25.2). Integumentary System Neoplasms of the integumentary system are common
and account for 12% to 70% of all avian neo-
plasms. 6,12,15,108 Of the various neoplasms reported, lipomas and fibrosarcomas are observed most fre-
quently. Adipose Neoplasms and Masses Neoplasms associated with fatty tissue and lipid
deposition in companion birds include lipoma,
myelolipoma, liposarcoma and hibernoma. Lesions
that mimic these neoplasms include xanthomas and
lipogranulomas. Definitive diagnosis of each of these
neoplasms or masses requires histopathologic exami-
nation of surgical biopsy specimens (Figure 25.1). Lipoma: Lipomas are benign proliferations of well differentiated adipocytes (lipocytes) that may exhibit
slow-to-rapid, progressive growth over time. Lipomas
are the most frequently observed neoplasm of com-
panion birds, with a reported incidence of 10% to 40%
in budgerigars. 143 Besides budgerigars, lipomas may be observed frequently in Rose-breasted Cockatoos
(galahs) and Amazon parrots. 98,143 Obesity, advancing age, species of bird and high-energy diets appear to
be predisposing factors for tumor development.
Based upon clinical observations, a genetic predispo-
sition to lipoma development may exist in budgeri-
gars. Lipomas usually arise in the subcutis of the sternal
or abdominal skin, but may also be observed on the
wings, back, neck, legs or near the uropygial
gland. 6,12,15,30,49,51,69,72,86,102,108,127 In addition, lipomas may occur in the thoracoabdominal cavity (arising
from thoracic or mesenteric fat, ovary, ventriculus
and liver) or in association with skeletal mus- cle. 12,40,102,108,127 Tumor size typically ranges from 0.3 to 4.0 cm in diameter (Color 25.2). Lipomas occur as single or multiple masses. Affected
birds may be presented for diagnosis of a visible skin
or subcutaneous mass or abdominal distention.
Large tumors may interfere with leg movement,
perching or flight. On palpation, lipomas are usually
well defined and soft; the overlying skin is freely
mobile. 143 Grossly, excised lipomas appear soft, round-to-mul-
tilobulated and pale yellow. On cut surface, they are
thinly encapsulated and fatty. Histologically, lipomas
appear as thinly encapsulated masses composed of
lobules of well differentiated adipocytes. Scattered FIG 25.1 A 15-year-old Amazon parrot was referred for evaluation
of a tumor. A previous veterinarian had advised euthanasia. A
large, pendulated, ulcerative mass was present on physical exami-
nation. The bird was in overall good condition, and abnormal
clinicopathologic findings were limited to a mild heterophilia
(18,000/
