International Journal of Urology
Blackwell Science, LtdOxford, UKIJUInternational Journal of Urology0919-81722003 Blackwell Publishing Asia Pty LtdNovember 20031011603606Case Report
Composite tumor of the kidneyM Takashi
Correspondence: Munehisa Takashi
Urology, Hekinan Municipal Hospital, 3-6 Heiwa-cho, Hek-
inan, Aichi 447-8502, Japan.
Received 30 September 2002; accepted 6 May 2003.
, Department of
Composite tumor of mucinous cystadenoma and
somatostatinoma of the kidney
Department of Pathology, School of Medicine and
for Comprehensive Medical Science, Fujita Health University, and
Medicine, Nagoya University Hospital, Aichi, Japan
Radiology, Hekinan Municipal Hospital,
Division of Pathological Cytology, Institute
Department of Laboratory
Approximately 30 cases of carcinoid tumor of the kidney have been reported in the English literature,
including three cases found as components of teratomas. Renal composite tumors associated with
somatostatinoma have not been described. A 53-year-old female presented with an incidentally found
right renal cystic lesion. Computed tomography demonstrated a cystic lesion associated with a solid
nodule in the right kidney and postcontrast dynamic MRI revealed enhancement of the solid nodule.
The patient underwent radical nephrectomy for the kidney lesion and is now well without recurrence
21 months after the operation. From the histopathological findings we diagnosed the cystic lesion
as a composite tumor composed of mucinous cystadenoma and carcinoid tumor. Immunohistochem-
istry demonstrated the majority of cells of in carcinoid portion to be positive for antisomatostatin
staining. The present case is the first documented composite tumor of mucinous cystadenoma and
somatostatinoma of the kidney.
composite tumor, kidney neoplasm, mucinous cystadenoma, somatostatinoma.
Carcinoid tumors usually occur in the gastrointestinal
and respiratory tracts, but only rarely occur in the uro-
genital system. Approximately 30 cases of carcinoid
tumor in the kidney have been reported in the English
literature, including three cases found as components of
In recent years neoplasms have been rec-
ognized containing histologically distinct and different
exocrine and endocrine tumor cells. These have been
designated as composite tumors.
been reported in many organs, including the esophagus,
stomach, colon, gall bladder, breast, prostate and uterine
cervix. However, no composite tumor with carcinoid
Such tumors have
differentiation has been found in the kidney to our
knowledge. We report here the first case of a composite
tumor consisting of mucinous cystadenoma and soma-
tostatinoma of the kidney, which was successfully
A 53-year-old female presented in October 1999 for
follow-up of urolithiasis. She had undergone pyelolitho-
tomy for left renal lithiasis at 19 years of age,
pyelolithotomy for right renal lithiasis at 33 years of
age, and shock wave lithotripsy for right renal lithiasis
at 40 years of age at another hospital. In May 2000,
ultrasonography incidentally revealed a round cystic
lesion with a diameter of about 2 cm in the right kidney.
In November 2000, follow-up ultrasonography showed
604 M Takashi
slight enlargement of the cystic lesion. Therefore, the
patient underwent further examinations including com-
puted tomography (CT) and magnetic resonance imag-
ing (MRI). CT demonstrated a solid nodule protruding
from the cystic lesion and a small calcified mass on the
wall of the cystic tumor (Fig. 1). Postcontrast dynamic
MRI demonstrated enhancement of the solid tumor nod-
ule, suggesting low-grade malignancy. No abnormal
findings were found by urinalysis or routine peripheral
blood examination. Findings of further roentgenologic
examinations for distant metastases were also negative.
In December 2000 the patient underwent radical nephre-
ctomy for the kidney lesion. No connection was found
between the kidney lesion and the pancreas.
The patient is now well without recurrence
21 months after the operation, with no lesions evident
in the pancreas, appendix or ovaries.
The resected kidney weighed 220 g. The cystic lesion
was localized in the anterior side of the lower part of
the kidney as detected by ultrasonography and CT. It
consisted mainly of the cystic tumor from which the
solid nodular tumor protruded (Fig. 2a). The cystic
tumor was unilocular and 27
taining abundant mucin and a small calcification
3 mm in size, in the lumen. About one-fourth of
the cystic wall was directly attached to parenchyma of
the renal medulla and pelvis. The solid nodular tumor
10 mm in size. The cut surface of the
tumor was soft, elastic and greyish-white in colour. His-
tological examination showed that the wall of the cystic
tumor contained two osteoid masses, one of which was
20 mm in size, con-
found on CT, and two small nodules consisting of tra-
beculae of endocrine cells. The cystic space was lined
by a smooth one-cell layer of tall cylindric cells, with a
few exceptional areas showing microvillous structure
(Fig. 2b). The osteoid masses were composed of osteoid
trabeculae, microcysts lined by mucinous cylindric cells
and of fairly large nests of endocrine-like cells. The
solid nodular tumor consisted of polygonal cells with
slightly atypical nuclei showing solid, trabecular and
ribbon-like structures (Fig. 2c). In the wall, numerous
minute endocrine tumor trabeculae were also scattered
in the fibrous mesenchyma. Luminal surfaces of muci-
nous columnar cells were strongly positive for anti-
CA19-9 antiserum and about 4% of their nuclei were
positive for anti-MIB-1 antibody. These findings are
those of typical mucinous cystadenomas. The majority
of cells of the solid nodular tumor and nests, and the
endocrine cell trabeculae in the cystic wall were positive
for antisomatostatin antiserum. A few cells of these
endocrine masses showed a strong reaction with anti-
pancreatic polypeptide antiserum. Neuron-specific eno-
lase and chromogranin A were identified in most tumor
cells, whereas insulin and serotonin were negative. Elec-
tron microscopic examination, performed with small
specimens cut from a paraffin-embedded block after
deparaffinization, demonstrated the majority of carci-
noid tumor cells to contain numerous round granules,
measuring around 210 nm, with moderate electron-
density (Fig. 2d). The granules were diagnosed as soma-
tostatin granules. No squamous epithelium, hair shafts
or pancreatic acini were found in the cystic tumor. A
diagnosis of composite tumor of mucinous cystadenoma
and somatostatinoma of the kidney was made.
Carcinoid tumors occur mostly in the gastrointestinal
and respiratory tracts, and rarely in the urogenital sys-
tem, including the kidney and the bladder. In 1966,
. first reported a case of carcinoid tumor
in the kidney, and 32 cases have subsequently been
reported in the English literature.
rare examples developing from teratoma tissues.
No gender predilection was evident for carcinoid
tumors of the kidney and the age of patients ranged
from 13 to 79 years, with an average of 50 years.
most common presenting symptoms were abdominal
pain and weight loss, followed by hematuria or pyuria
with or without fever.
Twenty percent of the patients
had no symptoms and the tumor was found inciden-
tally during a work-up for other conditions, as
occurred in the present case.
Among them were
ing a cystic tumor (arrowhead) with a solid nodular tumor
(arrrow) and a minute calcified mass in the right kidney.
Postenhanced computed tomography scan show-
Composite tumor of the kidney605
with peptide or amine production of carcinoid tumors
are well-known as a typical syndrome including devel-
opment of an abrupt rash and watery diarrhea. How-
ever, these symptoms are relatively rare in cases of
carcinoid tumors of the kidney.
known as suppressor of insulin and glucagon action,
and therefore, it is reasonable that no associated
symptoms were found preoperatively in the present
case. Serum samples were not available for the exami-
nation of production of peptides or amines. The lack
of specific ultrasonography, CT, MRI or angiography
findings precludes precise preoperative diagnosis.
. reported that 12 of 32 patients (38%)
were complicated because of distant metastases. Com-
mon metastatic sites include the retroperitoneal lymph
nodes, liver and bone.
The histogenesis of carcinoid tumors remains
unclear, although several hypotheses have been pro-
(APUD) endocrine cells, from which carcinoid tumors
are presumed to be derived, have not been demonstrated
in the normal kidney.
On the other hand, several inves-
tigators have speculated that undifferentiated primitive
cells are present, which have a potentiality of differen-
tiation towards neuroendocrine cells.
postulated that renal carcinoid tumors may arise from
neuroendocrine cells within foci of metaplastic or ter-
atomatous epithelium in the kidney.
composite tumors, such as in the present case, in which
mucinous cystadenoma and somatostatinoma are inter-
mingled in the kidney may suggest that the tumor orig-
inates from an endodermal-committed stem cell.
It has also been
The detection of
shrunken after the opening of the cystic cavity, and an oval solid nodular tumor (arrow) (original magnification
right side of the figure shows kidney parenchyma. (b) Microscopic appearance of part of the wall of the cystic tumor,
showing papillary projections and invaginations (H&E
350). (c) Microscopic appearance of part of the carcinoid tumor,
with solid, trabecular and ribbon-like structures (H&E
350). (d) Electron microscopic appearance of cells of the carcinoid
tumor, with numerous endocrine granules of medium electron density (original magnification
(a) Low power micrograph of the hilar part of the right kidney cut longitudinally, showing a cystic tumor (*)
606 M Takashi
Although the biological relationship between carcinoid
tumors and horseshoe kidney remains unclear, several
investigators have reported a link. Krishnan
reported that 16% of kidney carcinoid tumors occurred
in horseshoe kidneys, yielding a calculated relative risk
Recently, it has been recognized that there exists a
wide histologic spectrum of carcinoid tumors as well as
neoplasms containing various admixtures of neoplastic
endocrine and non-endocrine epithelial cells. The latter
have been designated as composite tumors
been reported in many organs, including the esophagus,
stomach, colon, gallbladder, breast, prostate and uterine
cervix. However, to our knowledge, no composite tumor
has hitherto been described in the kidney. Regarding
histogenesis, such neoplasms are speculated to arise
from multipotential stem cells. Carcinoid elements
sometimes show osteoid metaplasia,
present case. The interposition of a few pancreatic
polypeptide-positive cells in somatostatinomas is also
well-known in islet cell tumors of the pancreas. Hetero-
tropic pancreas might be speculated as a precursor of
the present composite tumor, but there have been no
reports of heterotropic pancreas or mucinous cystade-
noma in the kidney. Only one case report exists of soma-
tostatinoma in the kidney.
Surgical resection is the only curative treatment for
carcinoid tumors of the kidney and their rare occur-
rence precludes any evaluation of chemotherapy or
. suggested that tumor stage
at presentation is the most important factor for patient
survival and stressed the number of mitoses and
degree of cellular atypia as important pathologic
for 23 patients with carcinoid tumors of the kidney
followed-up for from 2 months to 8 years. Among
them, 16 were alive with no evidence of disease, four
had died of the disease, two were alive with the dis-
ease, and one had died of sepsis. Long-term follow-up
is mandatory and further clinical data should be accu-
as found in the
examined survival data
mulated to establish survival rates for patients with
this rare tumor.
We thank Dr Makoto Kuroda for his advice, and Mr
Masaaki Inoue and Dr Takamasa Hanaichi for their
expert technical assistance.
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