A nephroblastoma is the most common kidney malignancy in

A
3-year-old male white-handed gibbon (Hylobates
lar) was admitted to the University Veterinary Hospital, Universiti Putra
Malaysia with the complaint of chronic abdominal distention. At necropsy, there was a unilateral mass of polycystic
renal neoplasmin resembling an oversized kidney. On cut surface, the mass was
heterogenous with whitish admixed with some brownish structures, possibly remnants
of the left kidney and composed of cystic spaces separated
by delicate septa with some parts contained cartilaginous structures. There were no
sign of metastasis. Detailed
histopathologic investigation revealed heterogeneous mass
consisted of highly pleomorphic cells, which in most parts resembled primitive
nephrogenic cells forming primitive glomeruloid structures and cellular stroma.
The tumor is made up of a disorganized mixture of three distinct cell
populations: the epithelial, mesenchymal and blastemal cells. In
consideration of the macroscopic and histological findings, the tumor was
classified as nephroblastoma closely resembling the so-called Wilms’ tumor, a
malignant embryonic renal tumor frequently observed in humans, especially in
young 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’ tumor

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Wilms tumor or nephroblastoma
is the most common kidney malignancy in children
(~8% of all cancers of the child). It is an embryonal neoplasm composed of
three elements: blastema, epithelium, and stroma. This tumour is usually
unilateral but can be bilateral (5%). The highest incidence occurred at age 2-3
year (rarely above 10 years) and 70% were diagnosed before the age of 5 years
5. Only 10% -20% of all Wilms tumor cases who were diagnosed during the first
year of life. The prevalence of this tumour is 1 in 10,000 children. Wilms
tumor can affect men as well as women of equal comparability, and a higher
incidence in African American races than the Asian race or Caucasian. These
tumors are associated with certain congenital abnormalities and malformations
syndrome.

Most cases are
sporadic, about 1% are familial inherited derived autosomally dominant 5, 11.
The aetiology is multifactorial, but most of all is the involvement of the WT1
gene (Wilms Tumor Suppressor Gene 1). This gene lies on chromosome 11p13 and regulates
transcription factors that are essential for normal kidney development. The WT1
gene produced by metanephric mesenchyme (metanephric blastema), this gene
stimulates growth factors that play an important role in inducing ureteric bud
growth. (metanephric mesenchyme and ureteric bud are adult renal and ureteric
candidates). WT1 gene is a Suppressor Gene Tumor, if WT1 has a defect, there
will be no control of cell growth. These
tumors are pale gray (resembling the brain), the cells in them are metanephric
mesenchyme cells, primitive renal epithelial cells, and connective tissue.
Deletions on chromosome 11p13 (10% of cases), 11p15, and 16q have been reported
in some Wilms tumor patients and was associated with an increased risk of
developing 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 named
genes Wilms’ tumor 3 (WT3). The product of the WT 1 gene is a protein that
binds to the DNA found in the fetal kidney and genitourinary tissues. WT 2 and
WT 3 gene products are unknown. Based on the histologic picture, the tumor
wilms are divided into favorable (well differentiated) and unfavorable or anaplastic (poorly differentiated). The tumor begins in the kidney but
can 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, including
WAGR syndrome, and Denys-Drash syndrome.

In domestic
animals, 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 bovine
foetus, which was consist of several types of tissue with cartilage the
predominant type.

In nonhuman
primates, only a few cases have been documented as most of the cases were
incidental findings at necropsy after the animals had died spontaneously or had
been euthanatized because of an unspecific debilitated or moribund condition. The
most common renal neoplasms in nonhuman primates include carcinomas and
adenomas. Only a few reports have been documented about nephroblastomas in Old World
and New World monkeys; among them 1 case in a cynomolgus macaque (Macaca fascicularis), 2 recent cases in
baboons (Papio sp.), and 1 case in a cotton-top tamarin (Saguinus oedipus). To
the knowledge of the authors, this report documents the first description of a
cystic variant of malignant nephroblastoma in a white-handed
gibbon (Hylobates lar).

A 3-year-old
male white-handed gibbon (Hylobates lar)
was admitted to the University Veterinary Hospital, Universiti Putra Malaysia
with the complaint of chronic abdominal distention. Abdominal x-ray investigation reveals a
large soft tissue opacity displacing bowel. A complete necropsy
was performed and representative tissue samples of various organs, including
the kidneys, were fixed in 10% phosphate-buffered formaldehyde for histologic investigations.
Following fixation in 10% phosphate-buffered formaldehyde for at least 24
hours, tissue samples were automatically paraffin-embedded, sectioned at 3 mm, and
stained with hematoxylin and eosin (HE) for light microscopy.

At
necropsy, there was a unilateral mass of polycystic renal neoplasm resembling
an oversized kidney. On cut surface, the mass was heterogenous with whitish
admixed with some brownish structures, possibly remnants of the left kidney and
composed of cystic spaces separated by delicate septa with some parts contained
cartilaginous structures. Metastasis was not observed. Detailed histopathologic
investigation revealed heterogeneous mass consisted of highly pleomorphic
cells, which in most parts resembled primitive nephrogenic cells forming
primitive glomeruloid structures and cellular stroma. The neoplasm was composed
of a disorganized mixture of three distinct cell populations: the epithelial,
mesenchymal and blastemal cells. In consideration of the macroscopic and
histological findings, the tumor was classified as nephroblastoma closely
resembling the so-called Wilms’ tumor, a malignant embryonic renal tumor
frequently observed in humans, especially in young children.