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Metastasis of a myxoid leiomyosarcoma via the renal and hepatic portal circulation in a sarus crane (Grus antigone)
J. Comp. Path. 1993 Vol. 108, 57-63
M e t a s t a s i s o f a M y x o i d L e i o m y o s a r c o m a via the R e n a l a n d H e p a t i c Portal C i r c u l a t i o n in a Sarus C r a n e (Grus antigone) K. S. Frazier, A. J. Herron, M. E. Hines II, C. L. Miller*, G. T. H e n s l e y and N. H. Altman Deparlment of Pathology, Division of Comparative Pathology, University of Miami School of Medicine, P.O. Box 016960, Miami, FL 33101 and *Department of VeterinarySciences, Miami Metrozoo, Miami, FL 33177, U.S.A.
Summary A 12-year-old female sarus crane (Grus antigone) developed a recurrent proliferative lesion in the subcutaneous tissue of the tarsometatarsus, which failed to respond to medical and surgical therapy. The crane was killed and microscopic exam/nation of the tissues taken at necropsy revealed a myxomatous, poorly-differentiated sarcoma with metastasis to the liver and kidney. Immunohistochemical staining for muscle actin, smooth muscle myosin and vimentin were positive, indicating that the primary and metastatic tumours were leiomyosarcomas. Location of the metastatic lesions in only the portal venous system of the liver and veins of the kidney indicated that the route of metastasis was the portal circulation via the ischiatic vein, caudal mesenteric vein and both the renal-portal shunt and hepatic portal vein. This is the first report of metastatic subcutaneous leiomyosarcoma in an avian species.
Introduction Metastatic disease has been well documented in the medical and veterinary literature. Preferential implantation sites for most types of neoplasms have been described for both human and domestic animal cancers. Although metastatic neoplastic disease in avian species has often been reported in the literature, routes of spread and the organs frequently associated with distant metastasis for particular types of spontaneous tumours have not been adequately elucidated. This may be due to a number of factors, including the a p p a r e n t infrequency of non-virally induced metastatic cancer in birds (Dillberger, Citino and Altman, 1987) or the preferential use of mammalian models in h u m a n cancer research, providing more core research with mammalian than with avian neoplasms. It may also be related to a higher rate of fatalities from primary neoplasia before the occurrence of metastasis in avian patients, although studies supporting this premise have not been carried out. It is k n o w n that avian lymph nodes lack the size and organization of mammalian lyrnph nodes (Olah and Glick, 1983) and lack the filtering capacity of their m a m m a l i a n equivalents (Berens von Rautenfeld and Budras, 1983). This has 0021-9975/931010057 + 07 $08.00/0
© 1993 Academic Press Limited
58
K.S. Frazier e t al.
resulted in infrequent identification of lymph nodes during necropsy and consequent difficulty in evaluation of the potential lymphatic spread of avian carcinomas. Spontaneous avian spindle cell sarcomas (fibrosarcomas, leiomyosarcomas, rhabdomyosarcomas, etc.) have been frequently reported in the literature, but reports of metastasis of these tumours are rare ( H u b b a r d , Schmidt and Fletcher, 1983; Sasipreeyajan, N e w m a n and Brown, 1988). The haematogenous avenue of metastasis of mesenchymal tumours makes it difficult for the pathologist to identify the route by which sarcomas arrive at a distant organ. For these reasons, detailed analyses of metastatic patterns of spontaneous avian sarcomas have not been presented in the literature. Studies of avian metastasis have been limited to chemically induced fibrosarcomas in adult chickens or heterologous tumour implantation in chicken embryos (Kieran and Longenecker, 1983). This report describes a case of leiomyosarcoma in a sarus crane (Grus anligone) in which the apparent route of metastasis is identified. M a t e r i a l s and M e t h o d s
An approximately 12-year-old f~male sarus crane (Grus anligone) developed a proliferative lesion on the foot which was diagnosed as bumblefoot and treated with antibiotics, surgical debridement and bandaging {'or 5 months. The lesion resolved, with the outcome bcing residual ankylosis of most of the tbot and toe joints. A second lesion developed on the same lbot approximately 6 cm fi'om the original site. The bird was severely lame and this new lesion did not respond to medical therapy. The bird was killed approximately 3 weeks later with intravenous barbiturate. A necropsy was pertbrmed and samples of multiple tissues were submitted Ibr histopathological examination. Tissue samples were fixed in 10 per cent neutral buffered [brmalin, embedded in paraffin wax and stained with haematoxylin and eosin (HE). Sections from the subcutaneous mass and liver were also stained with Masson's trichrorne. Additional 3 I-tm sections o1" liver and subcutis were stained by an avidin-biotin complex immunoperoxidase method Ibr S100 protein (Dako Corp., Santa Barbara, CA, U.S.A.), cytokeratin AE 1/3 (Boehringer Mannheim, Indianapolis, IN, U.S,A,), factor VIII (Dab), desmin (Dako), smooth muscle (Sigma, St. Louis, MO, U.S.A.) and muscle actin (Enzo Diagnostics, New York, NY, U.S.A.). These specimens were counterstained with Harris's haematoxylin. The immunohistochemical methods used in our laboratory have been previously described by Brunnert, Herron and Altman
(1990).
Results
At necropsy, the crane was found to be in fair to poor feather and nutritional condition, with minimal body fat stores and moderate generalized muscle atrophy. The left foot had chronic ankylosis with fibrosis and mineralization of the entire foot-pad region and most of the plantar aspects of all toes. There was a large, proliferative, cavitated ¢ by 5 cm mass along the caudal aspect of the foot, involving' the hallux and the most distal-caudal portion of the tarsometatarsus. This mass consisted of highly vascular, gelatinous tissue involving or originating from the main digital flexor tendon sheath. There was some fibrino-necrotic debris within the cavity of the mass in the subcntis, which was removed through several skin incisions. The liver was slightly enlarged and
Metastatic Myxoid Leiornyosarcoma
59
diffusely speckled with small pale tan and green loci. There was moderate multifocal accumulation of black pigment along the peripheral aspects of the lungs. Both ventricles of the heart contained small foci of mural endocardial fibrosis. There were numerous, yellow, mineralized intimal plaques along the aortic arch and its major tributaries. Light microscopic examination of the affected subcutaneous tissue in the tarso-metatarsal area revealed a large focus of atypical spindle cells forming whorls and bundles, and areas of discrete cells embedded in a dense myxomatous matrix (Figs 1 and 2). There were overlying areas of granulation tissue and a mild, multifocal mixed infiltrate, composed primarily of heterophils. Scattered large multinucleated cells were also present. The spindle cells had oval to fusiform nuclei with often prominent nucleoli and occasional mitoses. Cells with a similar appearance were found in a number of veins of the kidney (Fig. 3) and the portal circulation of the liver. Other histological findings included severe, diffuse arteriosclerosis, pulmonary oedema and congestion, moderate, multifocal enteritis and severe myofibrillar degeneration of the pectoral and costosternal muscle groups. The Masson's trichrome stain results did not suggest a predominantly fibrous matrix in areas of tumour. The immunohistochemical stains used on the subcutaneous mass, kidney and liver demonstrated positive staining for muscle actin, smooth muscle myosin (Fig. 4) and vimentin, and negative staining for SI00 protein, cytokeratin AE1/3, desmin and factor V I I I antigen. Based on these findings, a diagnosis ofmyxoid leiomyosarcoma was made (Brunnert el al., 1990). Discussion
The undifferentiated, myxomatous characteristics of this smooth muscle tumour could also have been consistent with fibrosarcoma, neurofibrosarcoma, myxosarcoma or haemangiosarcoma. The positive staining for smooth muscle myosin and a specific muscle actin substantiated the diagnosis of leiomyosarcoma. These antibodies are specific for tumours of smooth muscle origin (Brunnert el aL, 1990). Although staining for desmin was negative, previous reports have shown inconsistent reactivity with anti-desmin antibodies in leiomyosarcomas (Brunnert et al., 1990). The positive s raining in lesions of both the kidney and the liver also provided evidence that the metastatic tumours were derived from the subcutaneous leiomyosarcoma of the foot. The morphological appearance of these tumours was consistent with a myxomatous sarcoma; however, immunoperoxidase stains for S100 protein, cytokeratin AEI/3 and factor V I I I antigen could exclude less likely tumours such as melanoma, epithelial neoplasms or haemangiosarcoma, respectively, from the differential list. While neoplasia is common in domestic poultry and psittacine birds (Blackmore, 1965; Siegfried, 1983), tumours in the Order Gruiformes have rarely been reported. A renal adenocarcinoma in a sarus crane has been previously described (Decker and Hruska, 1978) and a case ofosteoma in a North Island rail has been reported (Effron, Griner and Benirschke, 1977). There has also been a case of a cholangiocarcinoma in a sandhill crane (Allen, Martin and
60
K. S. F r a z i e r e t al.
Metastatic
Myxoid Leiomyosarcoma
61
Crowley, 1985). Leiomyosarcomas of the spleen, oviduct, thoracic cavity and j e j u n u m have been reported in budgerigars (Blackmore, 1965; Steinberg, 1988). In these reports, the thoracic tumour was metastatic to the bone marrow, spleen and liver (Sasipreeyajan et al., 1988) and two of the primary splenic tumours had metastasized to the liver. Leiomyosarcomas of the oviduct, ovaries, gastrointestinal tract and trachea have been described in chickens (Campbell, 1969). Although some of the cases in chickens contained metastatic lesions, many of these neoplasms were associated with the avian leukosis/ sarcoma complex and may have represented multicentric disease. Subcutaneous leiomyosarcomas are rare in domestic animals (Brunnert el al., 1990) and have not previously been reported in avian species. Subcutaneous leiomyosarcomas in m a n and domestic mammals are frequently solitary lesions found at the extremities and are believed to originate from smooth muscle cells present in vessel walls (Brunnert et al., 1990). T h e y are capable of metastasizing, but tend to do so late in the course of the disease (Hulland, 1990). Although there are numerous accounts of metastatic, non-haemopoietic, avian neoplasms in the literature, the vast majority of these have been either carcinomas, melanomas or tumours associated with the avian leukosis/sarcoma complex (Hubbard el al., 1983; Dillberger el al., 1987; Sasipreeyajan et al., 1988). Aside from the leiomyosarcomas mentioned earlier in budgerigars, reports of metastatic sarcomas in non-domestic or exotic birds are extremely rare (Raphael and Nguyen, 1980). One review of avian necropsies placed the incidence of sarcomas at 9"9 per cent of all avian neoplasms (Effron el al., 1977). However, this and other reviews of exotic animal necropsies have reported no metastasis of these sarcomas in birds (Hubbard el at., 1983; Kaneene, Taylor, Sikarskie, Meyer and Richter, 1985). It is well established that sarcomas preferentially metastasize through the blood, even though they are also sometimes found in lymph nodes. Invasive fibrosarcomas in domestic poultry frequently metastasize to the liver, kidneys, heart, lungs, pancreas and intestine (Campbell, 1969). M a n y of these have been associated with oncogenie viral infection. Fibrosarcomas are often myxomatous in chickens, including the classically described Rous sarcoma. However, it is extremely unlikely that the subcutaneous leiomyosarcoma in this case was associated with retroviral infection, since this was a case from an old bird in a closed flock with no previous history or clinical signs attributable to retroviral disease. In addition there have been no other reports of avian leukosis/sarcoma from the zoo. Finally, although retroviral sarcoma-like disease has been reported in a
Fig. 1.
Subcutaneous tissue of foot, sarus crane. Myxoid leiomyosareoma. Poorly-differentiated spindle eelN are ernbedded in a myxomatous matrix. A large muhinucleatcd cell is present at arrow. HE. Bar = 50 gm.
Fig. 2.
Subcutaneous tissue of loot, sarus crane, Myxoid leiomyosarcoma. Low power view of neoplastic spindle cells. HE. Bar = 100 gin Kidney, sarus crane. Metastatic leiomyosarcoma. Tumour cells are present within vein (arrow). HE. Bar = 50 pro.
Fig. 3, Fig. q,
Subcutaneous tissue of' [hot, sarus crane. Avidin-biofin complex immunoperoxidase stain for smooth muscle myosin Note positive staining at arrows, Bar = 50 pm
62
K . S . F r a z i e r e t al.
few rare cases in exotic avian species, this disease has never been reported in the Order Gruiformes. The renal-portal shunt is a unique anatomical circulatory feature present in birds, but absent in post-embryonic mammals. In avian species, the kidney is supplied by afferent venous blood via the renal-portal system, allowing the tubules a dual blood supply (Ringer, 1986). The ischiadie vein, which arises from veins in the distal extremities of the legs, joins the iliac vein, but first branches to form a connection with the caudal mesenteric vein. The caudal mesenteric vein terminates in both the hepatic portal vein and the renal-portal system. Usually, blood in the caudal mesenteric vein flows toward the kidney, but it can reverse its flow toward the liver (Ringer, 1986). This shunt is regulated by a portal valve at the junction of the external iliac vein and the renal vein. The valve is under the control of acetylcholine and epinephrine. The importance of this architectural arrangement is that blood from the hindlimbs as well as from the intestine and oviduct may pass through capillary beds in the liver and kidney before continuing on to the cardiopulmonary circulation. Since the location of the primary tumour was in the metatarsal area, metastatic neoplastic cells had access to the ischiadic vein and, therefore, the hepatic and renal portal circulation via the caudal mesenteric vein. According to the emboli-trapping model of metastasis, tumour cells often implant in the first capillary bed encountered (Kieran and Longenecker, 1983). This avenue of metastasis can further be supported by the fact that neoplastic cells were present in vessels at the primary site and the metastatic lesions in the liver were limited to the portal tributaries. The renal metastases were likewise present only in and around veins. The only plausible metastatic route to these areas is through the isehiadic vein, caudal mesenteric vein and then either the hepatic portal vein or renal-portal system. This is the first report ofleiomyosarcoma in the Order Gruiformes and is one of the few published cases of spontaneous metastatic sarcomas in avian species. The potential for metastasis through the portal systems is important for clinicians to realize when treating malignant sarcomas of the hindlimbs in birds, since it suggests the need for diagnostic procedures to determine the presence of hepatic and renal metastasis. It is also important for pathologists to realize that multiple sections of the liver and kidney may be necessary when performing a post-mortem examination of a bird with malignant sarcomas of the caudal extremities. Finally, it should be noted that the diagnosis in this case required the use ofimmunoperoxidase stains. Without immunohistochemistry, an imprecise diagnosis of myxosarcoma, fibrosarcoma, haemangiosarcoma or synovial cell sarcoma could have been ascribed to this case.
Acknowledgments This work was partially supported by NIH grants IP40RR04326-01 and 3-440-RR05088-051. We appreciate the assistance of Dr M. Nadji in performing the immunohistochemical stains.
Metastatic Myxoid Leiomyosareoma
63
References
Allen, J. L., Martin, H. D. and Crowley, A. M. (1985). Metastatic cholangiocarcinoma in Florida sandhill crane. Journal of the American Veterinary Medical Association, 187, 1215. Berens von Rautenfeld, D. and Budras, K.-D. (1983). Topography, ultrastructure and phagocytic capacity of avian lymph nodes. Cell and Tissue Research, 228, 389-403. Blackmore, D. K. (1965). The pathology and incidence of neoplasia in cage birds. Journal of Small Animal Practice, 6, 15-20. Brunnert, S. R., Herron, A. J. and Altman, N. H. (1990). Subcutaneous leiomyosarcoma in a Peruvian squirrel monkey. Veterinary Pathology, 27, 126-128. Campbell, J. G. (1969). Tumours of mesenchymal tissues. In: Tumours of the Fowl, Heinemann Medical Books, London, pp. 23-31, 41--47. Decker, R. A. and Hruska, J. C. (1978). Renal adenocarcinoma in a sarus crane. Journal of Zoo Animal Medicine, 9, 15-16. Dillberger, J. E., Citino, S. B. and Altman, N. H. (1987). Four cases of neoplasia in captive wild birds. Avian Diseases, 31,206-213. Effron, M., Griner, L. and Benirschke, K. (1977). Nature and rate of neoplasia found in captive wild mammals, birds, and reptiles at necropsy. Journal of the National Cancer Institute, 59, 185-194. Hubbard, G. B., Schmidt, R. E. and Fletcher, K. C. (1983). Neoplasia in zoo animals. Journal of Zoo Animal Medicine, 14, 33-40. Hulland, T . J . (1990). Tumours of the muscle. In: Turnouts in Domestic Animals, 3rd Edit. J. E. Moulton, Ed. Academic Press, Orlando, FL, p. 91. Kaneene, B., Taylor, R. F., Sikarskie, J. G., Meyer, M. and Richter, N. A. (1985). Disease patterns in the Detroit zoo: a study of the avian population from 1973 through 1983. Journal of the American Veterinary Medical Association, 187, 1129-1131. Kieran, M. W. and Longeneeker, B. M. (1983). Organ specific meeastasis with special reference to avian systems. Cancer Metastasb Review, 2, 165-182. Olah, I. and Glick, B. (1983). Avian lymph node: light and electron microscopic study. The Anatomical Record, 205, 287-299. Raphael, B. L. and Nguyen, H. T. (1980). Metastasizing rhabdomyosarcoma in a budgerigar. Journal oJ" the American Velerinary ivIedical Association, 177, 925-926. Ringer, R. K. (1986). Selected physiology [br the avian practitioner. In Clinical Avian Medicine and Surgery. G. Harrison and L. Harrison Eds, W. B. Saunders, Philadelphia, pp. 73-74, 58-65. Sasipreeyajan J., Newman, J. A. and Brown, P. A. (1988). Leiomyosareoma in a budgerigar (A/Ielopsittacus undulatus). Avian Diseases, 32, 163-165. Siegfried, L. M. (1983). Neoplasms identified in free-flying birds. Avian Diseases, 27, 86-99. Steinberg, H. (I 988). Leiomyosarcoma of the jejunum in a budgerigar. Avian Diseases, 32, 166-168.
I
Received, July 3rd, 1992 ] Accepted, October 151h, 1992]
M e t a s t a s i s o f a M y x o i d L e i o m y o s a r c o m a via the R e n a l a n d H e p a t i c Portal C i r c u l a t i o n in a Sarus C r a n e (Grus antigone) K. S. Frazier, A. J. Herron, M. E. Hines II, C. L. Miller*, G. T. H e n s l e y and N. H. Altman Deparlment of Pathology, Division of Comparative Pathology, University of Miami School of Medicine, P.O. Box 016960, Miami, FL 33101 and *Department of VeterinarySciences, Miami Metrozoo, Miami, FL 33177, U.S.A.
Summary A 12-year-old female sarus crane (Grus antigone) developed a recurrent proliferative lesion in the subcutaneous tissue of the tarsometatarsus, which failed to respond to medical and surgical therapy. The crane was killed and microscopic exam/nation of the tissues taken at necropsy revealed a myxomatous, poorly-differentiated sarcoma with metastasis to the liver and kidney. Immunohistochemical staining for muscle actin, smooth muscle myosin and vimentin were positive, indicating that the primary and metastatic tumours were leiomyosarcomas. Location of the metastatic lesions in only the portal venous system of the liver and veins of the kidney indicated that the route of metastasis was the portal circulation via the ischiatic vein, caudal mesenteric vein and both the renal-portal shunt and hepatic portal vein. This is the first report of metastatic subcutaneous leiomyosarcoma in an avian species.
Introduction Metastatic disease has been well documented in the medical and veterinary literature. Preferential implantation sites for most types of neoplasms have been described for both human and domestic animal cancers. Although metastatic neoplastic disease in avian species has often been reported in the literature, routes of spread and the organs frequently associated with distant metastasis for particular types of spontaneous tumours have not been adequately elucidated. This may be due to a number of factors, including the a p p a r e n t infrequency of non-virally induced metastatic cancer in birds (Dillberger, Citino and Altman, 1987) or the preferential use of mammalian models in h u m a n cancer research, providing more core research with mammalian than with avian neoplasms. It may also be related to a higher rate of fatalities from primary neoplasia before the occurrence of metastasis in avian patients, although studies supporting this premise have not been carried out. It is k n o w n that avian lymph nodes lack the size and organization of mammalian lyrnph nodes (Olah and Glick, 1983) and lack the filtering capacity of their m a m m a l i a n equivalents (Berens von Rautenfeld and Budras, 1983). This has 0021-9975/931010057 + 07 $08.00/0
© 1993 Academic Press Limited
58
K.S. Frazier e t al.
resulted in infrequent identification of lymph nodes during necropsy and consequent difficulty in evaluation of the potential lymphatic spread of avian carcinomas. Spontaneous avian spindle cell sarcomas (fibrosarcomas, leiomyosarcomas, rhabdomyosarcomas, etc.) have been frequently reported in the literature, but reports of metastasis of these tumours are rare ( H u b b a r d , Schmidt and Fletcher, 1983; Sasipreeyajan, N e w m a n and Brown, 1988). The haematogenous avenue of metastasis of mesenchymal tumours makes it difficult for the pathologist to identify the route by which sarcomas arrive at a distant organ. For these reasons, detailed analyses of metastatic patterns of spontaneous avian sarcomas have not been presented in the literature. Studies of avian metastasis have been limited to chemically induced fibrosarcomas in adult chickens or heterologous tumour implantation in chicken embryos (Kieran and Longenecker, 1983). This report describes a case of leiomyosarcoma in a sarus crane (Grus anligone) in which the apparent route of metastasis is identified. M a t e r i a l s and M e t h o d s
An approximately 12-year-old f~male sarus crane (Grus anligone) developed a proliferative lesion on the foot which was diagnosed as bumblefoot and treated with antibiotics, surgical debridement and bandaging {'or 5 months. The lesion resolved, with the outcome bcing residual ankylosis of most of the tbot and toe joints. A second lesion developed on the same lbot approximately 6 cm fi'om the original site. The bird was severely lame and this new lesion did not respond to medical therapy. The bird was killed approximately 3 weeks later with intravenous barbiturate. A necropsy was pertbrmed and samples of multiple tissues were submitted Ibr histopathological examination. Tissue samples were fixed in 10 per cent neutral buffered [brmalin, embedded in paraffin wax and stained with haematoxylin and eosin (HE). Sections from the subcutaneous mass and liver were also stained with Masson's trichrorne. Additional 3 I-tm sections o1" liver and subcutis were stained by an avidin-biotin complex immunoperoxidase method Ibr S100 protein (Dako Corp., Santa Barbara, CA, U.S.A.), cytokeratin AE 1/3 (Boehringer Mannheim, Indianapolis, IN, U.S,A,), factor VIII (Dab), desmin (Dako), smooth muscle (Sigma, St. Louis, MO, U.S.A.) and muscle actin (Enzo Diagnostics, New York, NY, U.S.A.). These specimens were counterstained with Harris's haematoxylin. The immunohistochemical methods used in our laboratory have been previously described by Brunnert, Herron and Altman
(1990).
Results
At necropsy, the crane was found to be in fair to poor feather and nutritional condition, with minimal body fat stores and moderate generalized muscle atrophy. The left foot had chronic ankylosis with fibrosis and mineralization of the entire foot-pad region and most of the plantar aspects of all toes. There was a large, proliferative, cavitated ¢ by 5 cm mass along the caudal aspect of the foot, involving' the hallux and the most distal-caudal portion of the tarsometatarsus. This mass consisted of highly vascular, gelatinous tissue involving or originating from the main digital flexor tendon sheath. There was some fibrino-necrotic debris within the cavity of the mass in the subcntis, which was removed through several skin incisions. The liver was slightly enlarged and
Metastatic Myxoid Leiornyosarcoma
59
diffusely speckled with small pale tan and green loci. There was moderate multifocal accumulation of black pigment along the peripheral aspects of the lungs. Both ventricles of the heart contained small foci of mural endocardial fibrosis. There were numerous, yellow, mineralized intimal plaques along the aortic arch and its major tributaries. Light microscopic examination of the affected subcutaneous tissue in the tarso-metatarsal area revealed a large focus of atypical spindle cells forming whorls and bundles, and areas of discrete cells embedded in a dense myxomatous matrix (Figs 1 and 2). There were overlying areas of granulation tissue and a mild, multifocal mixed infiltrate, composed primarily of heterophils. Scattered large multinucleated cells were also present. The spindle cells had oval to fusiform nuclei with often prominent nucleoli and occasional mitoses. Cells with a similar appearance were found in a number of veins of the kidney (Fig. 3) and the portal circulation of the liver. Other histological findings included severe, diffuse arteriosclerosis, pulmonary oedema and congestion, moderate, multifocal enteritis and severe myofibrillar degeneration of the pectoral and costosternal muscle groups. The Masson's trichrome stain results did not suggest a predominantly fibrous matrix in areas of tumour. The immunohistochemical stains used on the subcutaneous mass, kidney and liver demonstrated positive staining for muscle actin, smooth muscle myosin (Fig. 4) and vimentin, and negative staining for SI00 protein, cytokeratin AE1/3, desmin and factor V I I I antigen. Based on these findings, a diagnosis ofmyxoid leiomyosarcoma was made (Brunnert el al., 1990). Discussion
The undifferentiated, myxomatous characteristics of this smooth muscle tumour could also have been consistent with fibrosarcoma, neurofibrosarcoma, myxosarcoma or haemangiosarcoma. The positive staining for smooth muscle myosin and a specific muscle actin substantiated the diagnosis of leiomyosarcoma. These antibodies are specific for tumours of smooth muscle origin (Brunnert el aL, 1990). Although staining for desmin was negative, previous reports have shown inconsistent reactivity with anti-desmin antibodies in leiomyosarcomas (Brunnert et al., 1990). The positive s raining in lesions of both the kidney and the liver also provided evidence that the metastatic tumours were derived from the subcutaneous leiomyosarcoma of the foot. The morphological appearance of these tumours was consistent with a myxomatous sarcoma; however, immunoperoxidase stains for S100 protein, cytokeratin AEI/3 and factor V I I I antigen could exclude less likely tumours such as melanoma, epithelial neoplasms or haemangiosarcoma, respectively, from the differential list. While neoplasia is common in domestic poultry and psittacine birds (Blackmore, 1965; Siegfried, 1983), tumours in the Order Gruiformes have rarely been reported. A renal adenocarcinoma in a sarus crane has been previously described (Decker and Hruska, 1978) and a case ofosteoma in a North Island rail has been reported (Effron, Griner and Benirschke, 1977). There has also been a case of a cholangiocarcinoma in a sandhill crane (Allen, Martin and
60
K. S. F r a z i e r e t al.
Metastatic
Myxoid Leiomyosarcoma
61
Crowley, 1985). Leiomyosarcomas of the spleen, oviduct, thoracic cavity and j e j u n u m have been reported in budgerigars (Blackmore, 1965; Steinberg, 1988). In these reports, the thoracic tumour was metastatic to the bone marrow, spleen and liver (Sasipreeyajan et al., 1988) and two of the primary splenic tumours had metastasized to the liver. Leiomyosarcomas of the oviduct, ovaries, gastrointestinal tract and trachea have been described in chickens (Campbell, 1969). Although some of the cases in chickens contained metastatic lesions, many of these neoplasms were associated with the avian leukosis/ sarcoma complex and may have represented multicentric disease. Subcutaneous leiomyosarcomas are rare in domestic animals (Brunnert el al., 1990) and have not previously been reported in avian species. Subcutaneous leiomyosarcomas in m a n and domestic mammals are frequently solitary lesions found at the extremities and are believed to originate from smooth muscle cells present in vessel walls (Brunnert et al., 1990). T h e y are capable of metastasizing, but tend to do so late in the course of the disease (Hulland, 1990). Although there are numerous accounts of metastatic, non-haemopoietic, avian neoplasms in the literature, the vast majority of these have been either carcinomas, melanomas or tumours associated with the avian leukosis/sarcoma complex (Hubbard el al., 1983; Dillberger el al., 1987; Sasipreeyajan et al., 1988). Aside from the leiomyosarcomas mentioned earlier in budgerigars, reports of metastatic sarcomas in non-domestic or exotic birds are extremely rare (Raphael and Nguyen, 1980). One review of avian necropsies placed the incidence of sarcomas at 9"9 per cent of all avian neoplasms (Effron el al., 1977). However, this and other reviews of exotic animal necropsies have reported no metastasis of these sarcomas in birds (Hubbard el at., 1983; Kaneene, Taylor, Sikarskie, Meyer and Richter, 1985). It is well established that sarcomas preferentially metastasize through the blood, even though they are also sometimes found in lymph nodes. Invasive fibrosarcomas in domestic poultry frequently metastasize to the liver, kidneys, heart, lungs, pancreas and intestine (Campbell, 1969). M a n y of these have been associated with oncogenie viral infection. Fibrosarcomas are often myxomatous in chickens, including the classically described Rous sarcoma. However, it is extremely unlikely that the subcutaneous leiomyosarcoma in this case was associated with retroviral infection, since this was a case from an old bird in a closed flock with no previous history or clinical signs attributable to retroviral disease. In addition there have been no other reports of avian leukosis/sarcoma from the zoo. Finally, although retroviral sarcoma-like disease has been reported in a
Fig. 1.
Subcutaneous tissue of foot, sarus crane. Myxoid leiomyosareoma. Poorly-differentiated spindle eelN are ernbedded in a myxomatous matrix. A large muhinucleatcd cell is present at arrow. HE. Bar = 50 gm.
Fig. 2.
Subcutaneous tissue of loot, sarus crane, Myxoid leiomyosarcoma. Low power view of neoplastic spindle cells. HE. Bar = 100 gin Kidney, sarus crane. Metastatic leiomyosarcoma. Tumour cells are present within vein (arrow). HE. Bar = 50 pro.
Fig. 3, Fig. q,
Subcutaneous tissue of' [hot, sarus crane. Avidin-biofin complex immunoperoxidase stain for smooth muscle myosin Note positive staining at arrows, Bar = 50 pm
62
K . S . F r a z i e r e t al.
few rare cases in exotic avian species, this disease has never been reported in the Order Gruiformes. The renal-portal shunt is a unique anatomical circulatory feature present in birds, but absent in post-embryonic mammals. In avian species, the kidney is supplied by afferent venous blood via the renal-portal system, allowing the tubules a dual blood supply (Ringer, 1986). The ischiadie vein, which arises from veins in the distal extremities of the legs, joins the iliac vein, but first branches to form a connection with the caudal mesenteric vein. The caudal mesenteric vein terminates in both the hepatic portal vein and the renal-portal system. Usually, blood in the caudal mesenteric vein flows toward the kidney, but it can reverse its flow toward the liver (Ringer, 1986). This shunt is regulated by a portal valve at the junction of the external iliac vein and the renal vein. The valve is under the control of acetylcholine and epinephrine. The importance of this architectural arrangement is that blood from the hindlimbs as well as from the intestine and oviduct may pass through capillary beds in the liver and kidney before continuing on to the cardiopulmonary circulation. Since the location of the primary tumour was in the metatarsal area, metastatic neoplastic cells had access to the ischiadic vein and, therefore, the hepatic and renal portal circulation via the caudal mesenteric vein. According to the emboli-trapping model of metastasis, tumour cells often implant in the first capillary bed encountered (Kieran and Longenecker, 1983). This avenue of metastasis can further be supported by the fact that neoplastic cells were present in vessels at the primary site and the metastatic lesions in the liver were limited to the portal tributaries. The renal metastases were likewise present only in and around veins. The only plausible metastatic route to these areas is through the isehiadic vein, caudal mesenteric vein and then either the hepatic portal vein or renal-portal system. This is the first report ofleiomyosarcoma in the Order Gruiformes and is one of the few published cases of spontaneous metastatic sarcomas in avian species. The potential for metastasis through the portal systems is important for clinicians to realize when treating malignant sarcomas of the hindlimbs in birds, since it suggests the need for diagnostic procedures to determine the presence of hepatic and renal metastasis. It is also important for pathologists to realize that multiple sections of the liver and kidney may be necessary when performing a post-mortem examination of a bird with malignant sarcomas of the caudal extremities. Finally, it should be noted that the diagnosis in this case required the use ofimmunoperoxidase stains. Without immunohistochemistry, an imprecise diagnosis of myxosarcoma, fibrosarcoma, haemangiosarcoma or synovial cell sarcoma could have been ascribed to this case.
Acknowledgments This work was partially supported by NIH grants IP40RR04326-01 and 3-440-RR05088-051. We appreciate the assistance of Dr M. Nadji in performing the immunohistochemical stains.
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References
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Received, July 3rd, 1992 ] Accepted, October 151h, 1992]