CONCURRENT IRON OVERLOAD AND NEOPLASIA IN LESCHENAULT'S ROUSETTES (ROUSETTUS LESCHENAULTII): A CASE SERIES

This case series investigates a cluster of deaths in a captive colony of Leschenault's rousettes (Rousettus leschenaultii). Six of seven bats that died between March and September 2021 were diagnosed postmortem with both iron overload (IO) and neoplasia, neither of which have previously been reported in this species. Iron status was assessed via hepatic histopathological grading, hepatic iron concentration, and, in two cases, serum iron concentration. On histopathological grading, all cases had hemochromatosis except one, which had hemosiderosis. Hepatic iron concentrations did not correlate with histopathological grading. Neoplasms in these six bats included hepatocellular carcinoma (HCC; 4), bronchioloalveolar adenocarcinoma (1), pancreatic adenocarcinoma (1), and sarcoma of the spleen and stomach (1). One bat had two neoplasms (HCC and sarcoma of the spleen and stomach). One additional case of HCC in 2018 was identified on retrospective case review. Etiology was investigated to the extent possible in a clinical setting. Nutritional analysis and drinking water testing found oral iron intake within acceptable bounds; however, dietary vitamin C was potentially excessive and may have contributed to IO. Panhepadnavirus PCR testing of liver tissue was negative for all bats. A species-associated susceptibility to IO, as seen in Egyptian fruit bats (Rousettus aegyptiacus), is possible. The high incidence of HCC is suspected to be related to IO; other differentials include viral infection. Causes or contributing factors were not definitively identified for the other neoplasms seen but could include age, inherited risk (given a high level of inbreeding), or an oncogenic virus. Pending further research in this species, it is recommended that keepers of Leschenault's rousettes offer conservative amounts of vitamin C and iron (as for Egyptian fruit bats), submit for postmortem examination any euthanized or found dead, and share records of similar cases.

Hepatocellular carcinoma with lung metastasis showing hemochromatosis in an Egyptian fruit bat (Rousettus aegyptiacus)

After an Egyptian fruit bat (Rousettus aegyptiacus) in a zoo became emaciated and died, a necropsy revealed multiple nodules on the liver and lung surfaces. Microscopy revealed that the liver nodules consisted of neoplastic hepatocytes and showed metastasis in the lung lobes. Most of the neoplastic cells in the liver and lung showed positive labeling for HepPar-1, cytokeratin 19, glypican-3, and Ki-67. Hepatocellular degeneration and necrosis were diffuse in the liver parenchyma. Berlin blue staining revealed large amounts of iron in normal and neoplastic cells. Based on these pieces of evidence, this case was diagnosed as hepatocellular carcinoma with hemochromatosis. This is believed to be the first report of hepatocellular carcinoma in an Egyptian fruit bat that has been immunophenotypically examined in detail by pathological examination.

Skeletal Changes in Hemochromatosis of Salers Cattle

Hemochromatosis is an inherited defect in Salers cattle, characterized by increased iron absorption and wasting in young animals. Loss of teeth and soft bones has been reported. This study details bone changes in a prospective study of an affected Salers heifer and an age-matched, half-sibling control. The heifer fell 2 weeks before euthanasia, developed non-weight bearing lameness, and then became recumbent. At necropsy, the heifer was smaller than the control and had fractures of the humerus, femur, and ribs. Distinctive circumferential laminations in the outer third of the cortex were seen radiographically as layers of variably decreased density. In midshaft cross sections, the cortex was wider in some long bones, and fluorescent labeling revealed irregular and intermittent mineralization in the outer cortical layers. Mineral apposition rates in osteons of the inner cortex were decreased as compared with the control, and longitudinal bone formation at the growth plate was markedly decreased. Histologically, there were buried layers of osteopenic, poorly mineralized plexiform bone in outer circumferential lamellae. There was stainable iron in woven bone cores of the matrix. Iron was found in occasional osteoclasts as well. The mandible was severely affected, with loss of cortical bone as well as trabecular bone around the teeth and resorption of dental roots. Bone analysis revealed iron levels in the affected calf that were 30–50 times greater than the control and decreased percent ash in the outer cortex. These results indicate that periosteal dysplasia and osteopenia are responsible for pathologic fractures and tooth loss.

Feasibility Study of NMR Based Serum Metabolomic Profiling to Animal Health Monitoring: A Case Study on Iron Storage Disease in Captive Sumatran Rhinoceros (Dicerorhinus sumatrensis)

A variety of wildlife species maintained in captivity are susceptible to iron storage disease (ISD), or hemochromatosis, a disease resulting from the deposition of excess iron into insoluble iron clusters in soft tissue. Sumatran rhinoceros (Dicerorhinus sumatrensis) is one of the rhinoceros species that has evolutionarily adapted to a low-iron diet and is susceptible to iron overload. Hemosiderosis is reported at necropsy in many African black and Sumatran rhinoceroses but only a small number of animals reportedly die from hemochromatosis. The underlying cause and reasons for differences in susceptibility to hemochromatosis within the taxon remains unclear. Although serum ferritin concentrations have been useful in monitoring the progression of ISD in many species, there is some question regarding their value in diagnosing hemochromatosis in the Sumatran rhino. To investigate the metabolic changes during the development of hemochromatosis and possibly increase our understanding of its progression and individual susceptibility differences, the serum metabolome from a Sumatran rhinoceros was investigated by nuclear magnetic resonance (NMR)-based metabolomics. The study involved samples from female rhinoceros at the Cincinnati Zoo (n = 3), including two animals that died from liver failure caused by ISD, and the Sungai Dusun Rhinoceros Conservation Centre in Peninsular Malaysia (n = 4). Principal component analysis was performed to visually and statistically compare the metabolic profiles of the healthy animals. The results indicated that significant differences were present between the animals at the zoo and the animals in the conservation center. A comparison of the 43 serum metabolomes of three zoo rhinoceros showed two distinct groupings, healthy (n = 30) and unhealthy (n = 13). A total of eighteen altered metabolites were identified in healthy versus unhealthy samples. Results strongly suggest that NMR-based metabolomics is a valuable tool for animal health monitoring and may provide insight into the progression of this and other insidious diseases.

Epistasis in iron metabolism: complex interactions between Cp, Mon1a, and Slc40a1 loci and tissue iron in mice

Disorders of iron metabolism are among the most common acquired and constitutive diseases. Hemochromatosis has a solid genetic basis and in Northern European populations it is usually associated with homozygosity for the C282Y mutation in the HFE protein. However, the penetrance of this mutation is incomplete and the clinical presentation is highly variable. The rare and common variants identified so far as genetic modifiers of HFE-related hemochromatosis are unable to account for the phenotypic heterogeneity of this disorder. There are wide variations in the basal iron status of common inbred mouse strains, and this diversity may reflect the genetic background of the phenotypic diversity under pathological conditions. We therefore examined the genetic basis of iron homeostasis using quantitative trait loci mapping applied to the HcB-15 recombinant congenic strains for tissue and serum iron indices. Two highly significant QTL containing either the N374S Mon1a mutation or the Ferroportin locus were found to be major determinants in spleen and liver iron loading. Interestingly, when considering possible epistatic interactions, the effects of Mon1a on macrophage iron export are conditioned by the genotype at the Slc40a1 locus. Only mice that are C57BL/10ScSnA homozygous at both loci display a lower spleen iron burden. Furthermore, the liver-iron lowering effect of the N374S Mon1a mutation is observed only in mice that display a nonsense mutation in the Ceruloplasmin (Cp) gene. This study highlights the existence of genetic interactions between Cp, Mon1a, and the Slc40a1 locus in iron metabolism, suggesting that epistasis may be a crucial determinant of the variable biological and clinical presentations in iron disorders.

Iron indices in bottlenose dolphins (Tursiops truncatus)

Bottlenose dolphins can have iron overload (that is, hemochromatosis), and managed populations of dolphins may be more susceptible to this disease than are wild dolphins. Serum iron, total iron-binding capacity (TIBC), transferrin saturation, and ferritin were measured in 181 samples from 141 dolphins in 2 managed collections and 2 free-ranging populations. Although no iron indices increased with age among free-ranging dolphins, ferritin increased with age in managed collections. Dolphins from managed collections had higher iron, ferritin, and transferrin saturation values than did free-ranging dolphins. Dolphins with high serum iron (exceeding 300 μg/dL) were more likely to have elevated ferritin but not ceruloplasmin or haptoglobin, demonstrating that high serum levels of iron are due to a true increase in total body iron. A time-series study of 4 dolphins with hemochromatosis that were treated with phlebotomy demonstrated significant decreases in serum ferritin, iron, and TIBC between pre- and posttreatment samples; transferrin saturation initially fell but returned to prephlebotomy levels by 6 mo after treatment. Compared with those in managed collections, wild dolphins were 15 times more likely to have low serum iron (100 μg/dL or less), and this measure was associated with lower haptoglobin. In conclusion, bottlenose dolphins in managed collections are more likely to have greater iron stores than are free-ranging dolphins. Determining why this situation occurs among some dolphin populations and not others may improve the treatment of hemochromatosis in dolphins and provide clues to causes of nonhereditary hemochromatosis in humans.

Erythrocytic pyruvate kinase mutations causing hemolytic anemia, osteosclerosis, and secondary hemochromatosis in dogs

BACKGROUND

Erythrocytic pyruvate kinase (PK) deficiency, first documented in Basenjis, is the most common inherited erythroenzymopathy in dogs.

OBJECTIVES

To report 3 new breed-specific PK-LR gene mutations and a retrospective survey of PK mutations in as mall and selected group of Beagles and West Highland White Terriers (WHWT).

ANIMALS

Labrador Retrievers (2 siblings, 5 unrelated), Pugs (2 siblings, 1 unrelated), Beagles (39 anemic, 29 other),WHWTs (22 anemic, 226 nonanemic), Cairn Terrier (n = 1).

METHODS

Exons of the PK-LR gene were sequenced from genomic DNA of young dogs (<2 years) with persistent highly regenerative hemolytic anemia.

RESULTS

A nonsense mutation (c.799C>T) resulting in a premature stop codon was identified in anemic Labrador Retriever siblings that had osteosclerosis, high serum ferritin concentrations, and severe hepatic secondary hemochromatosis. Anemic Pug and Beagle revealed 2 different missense mutations (c.848T>C, c.994G>A, respectively) resulting in intolerable amino acid changes to protein structure and enzyme function. Breed-specific mutation tests were developed. Among the biased group of 248 WHWTs, 9% and 35% were homozygous (affected) and heterozygous, respectively, for the previously described mutation (mutant allele frequency 0.26). A PK-deficient Cairn Terrier had the same insertion mutation as the affected WHWTs. Of the selected group of 68 Beagles, 35% were PK-deficient and 3% were carriers (0.37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Erythrocytic PK deficiency is caused by different mutations in different dog breeds and causes chronic severe hemolytic anemia, hemosiderosis, and secondary hemochromatosis because of chronic hemolysis and, an as yet unexplained osteosclerosis. The newly developed breed-specific mutation assays simplify the diagnosis of PK deficiency.

Survey and clinical application of serum iron, total iron binding capacity, transferrin saturation, and serum ferritin in captive black and white ruffed lemurs (Varecia variegata variegata)

Serum samples from 63 clinically normal captive black and white ruffed lemurs (Varecia variegata variegata) were analyzed to survey serum iron, total iron binding capacity, transferrin saturation, and serum ferritin levels. Data analysis showed no differences in these analytes attributable to sex, but significantly higher levels of serum iron, transferrin saturation, and serum ferritin in older animals. The survey data were examined in light of two black and white ruffed lemurs that were treated for iron overload with serial phlebotomies. Prior to therapy, both phlebotomized lemurs had excess hepatic iron deposition, but had serum iron, transferrin saturation, and serum ferritin below the upper limits observed in the survey animals, suggesting that some clinically normal animals included in the survey may have accumulated excess systemic iron. Serial phlebotomy therapy reduced serum iron, transferrin saturation, and serum ferritin in both animals. Three years after the conclusion of therapy in the one remaining case, serum iron and transferrin saturation have risen substantially, whereas serum ferritin has risen slightly. Serum iron, transferrin saturation, and serum ferritin may be useful predictors of systemic iron stores in this species, though the correlation between these parameters and systemic iron stores needs to be determined.

IRON STORAGE DISEASE IN CAPTIVE EGYPTIAN FRUIT BATS (ROUSETTUS AEGYPTIACUS): RELATIONSHIP OF BLOOD IRON PARAMETERS TO HEPATIC IRON CONCENTRATIONS AND HEPATIC HISTOPATHOLOGY

This study evaluated the relationship between blood iron parameters and hepatic iron concentrations, and correlation of histologic findings with hepatic iron concentrations in a captive population of Egyptian fruit bats (Rousettus aegyptiacus) and island flying foxes (Pteropus hypomelanus). Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron concentrations, total iron-binding capacity, whole-blood lead concentrations, and plasma ferritin assays. Liver samples obtained by laparotomy were divided, with one half processed for histologic examination and the other half frozen and submitted for tissue mineral analysis. The histologic sections were scored by two blinded observers for iron deposition, necrosis, and fibrosis. The Egyptian fruit bats had significantly higher liver iron (mean = 3,669 +/- 1,823 ppm) and lead (mean = 8.9 +/- 5.8 ppm) concentrations than the island flying foxes (mean [Fe] = 174 +/- 173 ppm, mean [Pb] = 1.9 +/- 0.5 ppm). Hepatic iron concentrations significantly correlated with tissue lead concentrations, histologic grading for iron and necrosis, serum iron, transferrin saturation, and plasma ferritin (P < 0.001). Blood lead concentrations negatively correlated with tissue lead concentrations (P < 0.001). When the product of transferrin saturation and serum iron was greater than 51, an individual animal had a high probability of having iron overload. When the product of these two variables was greater than 90, there was a high probability that the animal had hemochromatosis. On the basis of this study, it appears that evaluation of serum iron, transferrin saturation, and plasma ferritin are useful and noninvasive methods for diagnosis of hemochromatosis in Egyptian fruit bats.

Foci of altered hepatocytes in a fox squirrel (Sciurus niger) with haemochromatosis

Numerous minute milky white foci were distributed throughout the dark brown liver in an adult male fox squirrel. Histologically, the hepatic focal lesions were composed of large eosinophilic granular hepatocytes, which were mostly positive for glutathione S-transferase mu antigen and proliferating cell nuclear antigen. Electron microscopy demonstrated an increased number of mitochondria. These features corresponded to those in the eosinophilic type of foci of altered hepatocytes. Berlin blue stain showed severe haemosiderin deposition in hepatocytes, except in the focal lesions. Since the fox squirrel is known to be liable to develop congenital porphyria, it is suggested that the hepatic anomalies described may be closely associated with the development of porphyria.

Use of desferoxamine and S-adenosylmethionine to treat hemochromatosis in a red ruffed lemur (Varecia variegata ruber)

Hemochromatosis was diagnosed in a 14-year-old, male, red ruffed lemur (Varecia variegata ruber) on the basis of abnormal results of serum biochemical analysis, including high serum ferritin and transferrin saturation values, and of liver biopsy. Therapy included chelation, using desferoxamine to remove excess iron and S-adenosylmethionine to improve liver function, and monthly peripheral blood removal by phlebotomy to reduce total body iron content. Response to treatment was assessed by changes in the lemur's attitude and appetite, as well as variations in serum biochemical and iron panel values. Initial improvement was associated with the onset of therapy. After 56 days of treatment, results of serum biochemical analysis indicated a decrease in iron panel values. Treatment was temporarily discontinued from days 56 to 65, and the lemur's condition worsened, so therapy was re-instituted. However, the lemur died of hepatocellular carcinoma on day 110 of treatment.

First cases of animal diseases published since 2000. 1. Dogs

In this first article of a series of papers listing first case reports of animal diseases published since 2000, the following 19 cases of dog diseases are discussed: Blastomycotic granuloma involving the cranial vena cava. Congenital myocardial hamartoma. Discospondylitis: three cases caused respectively by Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus epidermidis. Dystrophin deficient muscular dystrophy in a Labrador Retriever. Emphysematous prostatitis. Erythema multiforme major caused by a Parvovirus infection of keratinocytes. Hemochromatosis due to repeated blood transfusions. Intraspinal synovial cyst. Juvenile nephropathy in the Collie and the Irish Wolfhound. Primary cerebellar cortical degeneration (abiotrophy) in a Scottish terrier. Primary pulmonary artery chondrosarcoma. Renal dysplasia in a Bull Mastiff. Rhabdomyosarcoma (botryoid sarcoma) of the urinary bladder in a Maltese. Spinal mast cell tumor. Spongiform degeneration of the white matter in the central nervous system of Australian Cattle dog. Systemic pasteurellosis caused by Pasteurella canis. Thymic hemorrhage caused by dicumarol intoxication. Undimerized biclonal gammopathy with a single heavy chain class IgA in a dog with multiple myeloma. After a short introduction, the bibliographical data and the abstract of the author(s) and mostly some additional information derived from the article are given. The article will be regularly updated adding overlooked as well as new first reports.

Hemochromatosis secondary to repeated blood transfusions in a dog

Hemochromatosis was presumptively diagnosed using cytologic examination of liver tissue from an aged male Miniature Schnauzer. The dog was presented after receiving whole blood transfusion every 6-8 weeks for 3 years to treat pure red cell aplasia. The cytologic specimen contained clusters of hepatocytes with abundant intracytoplasmic gold-yellow pigment granules and clumps of extracellular, green-black, globular pigment, both interpreted to be hemosiderin. Histologic sections of liver revealed hepatocellular degeneration with bridging portal fibrosis, lobular atrophy, biliary hyperplasia, and diffuse, severe hemosiderin accumulation. Serum iron and ferritin levels, and dry-weight iron concentrations of liver, heart, and kidneys were markedly increased. Hemosiderin accumulation was confirmed in hepatocytes of cytologic and histologic specimens using Perl's Prussian blue staining. This report is the first description of transfusional hemochromatosis in a dog and is the first to describe its cytologic appearance in a veterinary patient.

[Composition of commercial feeds for mynah birds with particular attention to the iron content]

The composition of 12 commercial feeds for mynah birds was analysed, with special attention being paid to the iron content. To prevent iron overload, the iron content of such diets should be maximally 5 mg/MJ, which is equivalent to 100 mg iron/kg if the commercial diet is the sole food source. Only three of the 12 feeds met this requirement. In all feeds the iron content was minimally three times higher than the recently suggested iron requirement of 25 mg/kg. In general, the total iron intake is not reduced sufficiently by providing cooked rice or fruit together with commercial feeds.

Hepatic failure and hemochromatosis of Salers and Salers-cross cattle

Hemochromatosis is rare in domestic mammals. Five clinical cases and one preclinical case of hemochromatosis were diagnosed in Salers and Salers-cross cattle. Clinical disease developed between 9 and 22 months of age. Animals were healthy until weaning but then lost weight, developed rough hair coats, and lost incisor teeth. In two animals, hemochromatosis was identified by liver biopsy, biochemical evidence of hepatic injury, and/or elevated transferrin saturation values. At necropsy, carcasses were thin, with firm dark brown livers and lymph nodes, soft bones, and brown-colored small bowel. The principal histologic changes were hepatocellular siderosis and periportal, bridging, and perivenular fibrosis. Siderocalcinosis involved collagen, elastin, reticulin, and basement membrane components in liver, lymph nodes, spleen, duodenum, and kidney. Hepatic iron concentrations in clinically affected cattle were 1,500-10,500 microg/g wet weight (reference range for cattle = <300 microg/ g). Ultrastructurally, the heaviest intrahepatic deposition was in hepatocytes, which contained large intracytoplasmic siderosomes. Iron deposition in bone was associated with osteopenia. Genetic analysis indicated a common ancestral bull in the pedigrees of five of six affected cattle; no pedigree was available for the remaining animal. Four dams of five affected animals were phenotypically normal and had histologically normal livers. Test mating of four cows to the ancestral bull resulted in a female calf that developed clinicopathologic and histologic evidence of preclinical hemochromatosis by 40 days of age. It was not possible to establish the pattern of inheritance because of the small number of pedigrees from affected cattle.

Quantitative image analysis as an alternative to chemical analysis for follow-up of liver biopsies from a toucan with hemochromatosis. A technique with potential value for the follow-up of hemochromatosis in humans

OBJECTIVE

To compare the reliability of quantitative image analysis of histologic sections versus chemical analysis for determination of the iron content of serial liver biopsies taken at regular intervals after the onset of treatment, in a case of hemochromatosis in a channel-billed toucan treated with deferoxaminemesilate in combination with a low-iron diet.

STUDY DESIGN

Two different image analysis systems were used, one developed for working with black-and-white pictures and another capable of processing colored images. Using Pearson's correlation test, the results with both quantitative image analysis systems were compared to the results obtained by chemical analysis.

RESULTS

There was a good correlation between the results of chemical analysis and those obtained with each of the two image analysis systems (0.86 and 0.89, respectively, with a confidence interval of 95%). The results of these serial liver biopsies indicated that the bird responded well to treatment.

CONCLUSION

Quantitative image analysis can be used to evaluate follow-up of this disease in toucans as an alternative to chemical determination of the iron content in biopsies of the liver. this technique may have potential value in follow-up of hemochromatosis in humans.

Hepatic cirrhosis and hemochromatosis in three horses

Hemochromatosis, an iron storage disease, was diagnosed in 3 horses with hepatic cirrhosis. Each horse had bridging portal fibrosis and abundant iron deposits in the cytoplasm of hepatocytes. Serum concentrations of liver-derived enzymes and total bile acids were high. However, serum iron concentration was not high, and iron binding capacity was only 46% saturated in the 1 horse in which it was measured. However, the concentration of iron in the liver of this horse was 20 times the reference limits. Hemochromatosis is common in mynah birds and human beings. There are several types of this iron storage disease. In human beings, there is a familial disease with iron absorption inappropriate for the level of stored iron. Hemochromatosis also occurs secondary to cirrhosis of the liver, and in certain anemia diseases. Another type of hemochromatosis is seen in association with dietary iron overload. These horses were not related, and there was not any evidence of high dietary iron intake.

Hemochromatosis in Salers cattle

Two 2-year-old Salers cattle from different herds raised on pasture were evaluated for retarded growth and diarrhea. Increase of liver enzyme activities and prolonged sulfobromophothalein (BSP) half life (T1/2) indicated liver disease with impaired liver function. Histopathologic examination of liver biopsies revealed a micronodular cirrhosis with marked deposition of hemosiderin in hepatocytes, Kupffer cells, and arterioles. Transferrin saturation (TS) and liver iron content were markedly increased, consistent with a diagnosis of hemochromatosis. Both animals were euthanatized due to deterioration in their condition. Necropsy findings included hepatomegaly and hemosiderin accumulation in the liver, lymph nodes, pancreas, spleen, thyroid, kidney, brain and other glandular tissue. Continued surveillance of the second herd (serum iron, total iron binding capacity [TIBC], unsaturated iron binding capacity [UIBC], and TS), identified a heifer as a hemochromatosis suspect in a subsequent generation. Liver biopsies from that animal revealed the same histopathologic changes as the previous 2 animals, and similar increases in liver iron content (8,700 ppm, normal range 45 to 300 ppm). The 3 affected cattle were all products of line breeding programs and shared a common ancestor. The absence of dietary iron loading in conjunction with the histopathologic and metabolic findings were consistent with a diagnosis of primary hemochromatosis. The reported disease is similar to idiopathic hemochromatosis in human beings in which there is a hereditary defect in iron metabolism.

Amyloidosis, hemochromatosis, and atherosclerosis in a roseate flamingo (Phoenicopterus ruber)

An aged male roseate flamingo, in a private collection in the British Virgin Islands, was found acutely "down." After four days of supportive therapy, the flamingo succumbed. At necropsy gross lesions included emaciation; collapsed and thickened, yellow abdominal air sac; dark red liver, partially covered by friable yellow material; and a raised, intimal plaque in the aorta near the iliac trifurcation. Histologic examination revealed severe, diffuse, pyogranulomatous air sacculitis with associated locally extensive pleuroperitonitis/perihepatitis. Pansystemic, predominantly periarteriolar distribution of amyloid deposition was evident, as was massive intrahepatocellular accumulation of iron pigment (hemachromatosis/hemosiderosis). A locally extensive, nonobstructive, fibroatheromatous plaque was present in the distal aorta. Amyloidosis, hemochromatosis/hemosiderosis, and atherosclerosis have been recognized in Phoenicopteriformes and other marine or aquatic birds. Their pathogenesis and pathogenicity remain a matter of debate.

Hepatopathy and lymphosarcoma in a mynah bird with excessive iron storage

Hemochromatosis and hepatic neoplasia were diagnosed in a mynah bird. Poorly differentiated cells were identified ultrastructurally as neoplastic lymphocytes.