A3-year-old male white-handed gibbon (Hylobateslar) was admitted to the University Veterinary Hospital, Universiti PutraMalaysia with the complaint of chronic abdominal distention. At necropsy, there was a unilateral mass of polycysticrenal neoplasmin resembling an oversized kidney. On cut surface, the mass washeterogenous with whitish admixed with some brownish structures, possibly remnantsof the left kidney and composed of cystic spaces separatedby delicate septa with some parts contained cartilaginous structures. There were nosign of metastasis. Detailedhistopathologic investigation revealed heterogeneous massconsisted of highly pleomorphic cells, which in most parts resembled primitivenephrogenic cells forming primitive glomeruloid structures and cellular stroma.The tumor is made up of a disorganized mixture of three distinct cellpopulations: the epithelial, mesenchymal and blastemal cells. Inconsideration of the macroscopic and histological findings, the tumor wasclassified as nephroblastoma closely resembling the so-called Wilms’ tumor, amalignant embryonic renal tumor frequently observed in humans, especially inyoung children.
This tumor is rarely been observed in non-human primates thus,little is known about the natural behavior of this tumor in non-human primate.Keywords: Hylobateslar, nephroblastoma,cysts, renal neoplasm, Wilms’ tumorWilms tumor or nephroblastomais the most common kidney malignancy in children(~8% of all cancers of the child). It is an embryonal neoplasm composed ofthree elements: blastema, epithelium, and stroma. This tumour is usuallyunilateral but can be bilateral (5%). The highest incidence occurred at age 2-3year (rarely above 10 years) and 70% were diagnosed before the age of 5 years5. Only 10% -20% of all Wilms tumor cases who were diagnosed during the firstyear of life. The prevalence of this tumour is 1 in 10,000 children. Wilmstumor can affect men as well as women of equal comparability, and a higherincidence in African American races than the Asian race or Caucasian.
Thesetumors are associated with certain congenital abnormalities and malformationssyndrome. Most cases aresporadic, about 1% are familial inherited derived autosomally dominant 5, 11.The aetiology is multifactorial, but most of all is the involvement of the WT1gene (Wilms Tumor Suppressor Gene 1). This gene lies on chromosome 11p13 and regulatestranscription factors that are essential for normal kidney development. The WT1gene produced by metanephric mesenchyme (metanephric blastema), this genestimulates growth factors that play an important role in inducing ureteric budgrowth. (metanephric mesenchyme and ureteric bud are adult renal and uretericcandidates). WT1 gene is a Suppressor Gene Tumor, if WT1 has a defect, therewill be no control of cell growth.
Thesetumors are pale gray (resembling the brain), the cells in them are metanephricmesenchyme cells, primitive renal epithelial cells, and connective tissue.Deletions on chromosome 11p13 (10% of cases), 11p15, and 16q have been reportedin some Wilms tumor patients and was associated with an increased risk ofdeveloping the tumor. Gen 11p13 named after the Wilms’ tumor 1 (WT1) gene;genes 11p15 named after Wilms’ tumor 2 (WT2) genes; and the 16q gene is namedgenes Wilms’ tumor 3 (WT3). The product of the WT 1 gene is a protein thatbinds to the DNA found in the fetal kidney and genitourinary tissues. WT 2 andWT 3 gene products are unknown. Based on the histologic picture, the tumorwilms are divided into favorable (well differentiated) and unfavorable or anaplastic (poorly differentiated).
The tumor begins in the kidney butcan invade the surrounding organs, spreading lymphogenously or hematogenously.The most frequent metastases are in the lung (85%) and in the liver (10%). Congenital abnormalities occur in 12%-15% of cases. The most common congenital abnormalities are aniridia, hemihipertrophy,Beckwith-Wiedemann Syndrome, and genitourinary tract abnormalities, includingWAGR syndrome, and Denys-Drash syndrome.In domesticanimals, primary nephroblastoma most commonly found in chickens and pigs 7, 11. Few cases has been reported in dogs,cats, horses and cattle and rarely have been reported in nonhuman primates 7,11. An extrarenal manifestation of nephroblastoma has been observed in bovinefoetus, which was consist of several types of tissue with cartilage thepredominant type.
In nonhumanprimates, only a few cases have been documented as most of the cases wereincidental findings at necropsy after the animals had died spontaneously or hadbeen euthanatized because of an unspecific debilitated or moribund condition. Themost common renal neoplasms in nonhuman primates include carcinomas andadenomas. Only a few reports have been documented about nephroblastomas in Old Worldand New World monkeys; among them 1 case in a cynomolgus macaque (Macaca fascicularis), 2 recent cases inbaboons (Papio sp.), and 1 case in a cotton-top tamarin (Saguinus oedipus).
Tothe knowledge of the authors, this report documents the first description of acystic variant of malignant nephroblastoma in a white-handedgibbon (Hylobates lar).A 3-year-oldmale white-handed gibbon (Hylobates lar)was admitted to the University Veterinary Hospital, Universiti Putra Malaysiawith the complaint of chronic abdominal distention. Abdominal x-ray investigation reveals alarge soft tissue opacity displacing bowel. A complete necropsywas performed and representative tissue samples of various organs, includingthe kidneys, were fixed in 10% phosphate-buffered formaldehyde for histologic investigations.Following fixation in 10% phosphate-buffered formaldehyde for at least 24hours, tissue samples were automatically paraffin-embedded, sectioned at 3 mm, andstained with hematoxylin and eosin (HE) for light microscopy.Atnecropsy, there was a unilateral mass of polycystic renal neoplasm resemblingan oversized kidney. On cut surface, the mass was heterogenous with whitishadmixed with some brownish structures, possibly remnants of the left kidney andcomposed of cystic spaces separated by delicate septa with some parts containedcartilaginous structures.
Metastasis was not observed. Detailed histopathologicinvestigation revealed heterogeneous mass consisted of highly pleomorphiccells, which in most parts resembled primitive nephrogenic cells formingprimitive glomeruloid structures and cellular stroma. The neoplasm was composedof a disorganized mixture of three distinct cell populations: the epithelial,mesenchymal and blastemal cells.
In consideration of the macroscopic andhistological findings, the tumor was classified as nephroblastoma closelyresembling the so-called Wilms’ tumor, a malignant embryonic renal tumorfrequently observed in humans, especially in young children.