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DOI: 10.5146/tjpath.2017.01418 |
Primary Renal Neuroendocrine Tumour Presenting as an Enormous Cystic Lesion |
Azfar NEYAZ1, Zafar NEYAZ2, Nuzhat HUSAİN1, Vani GUPTA1 |
1Dr. Ram Manohar Lohia Institute of Medical Sciences, Department of Pathology, LUCKNOW, INDIA 2Sanjay Gandhi Postgraduate Institute of Medical Sciences, Department of Radiodiagnosis, LUCKNOW, INDIA |
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Dear Editor,
Primary Renal Neuroendocrine tumors (NETs) are
extremely rare in the kidney, with fewer than 100 cases
reported1. NETs usually present as solid tumors with or
without cystic components. We report a rare presentation
of a well-differentiated neuroendocrine tumor as a large
completely cystic lesion in the right kidney without any
evidence of metastasis or carcinoid syndrome. Very few
case reports of NETs of such a large size have, so far, been
reported in literature. A 47-year-old man presented with
an incidentally detected large non-tender and mobile
mass in the right iliac fossa. USG showed a large 23.5 x
14.0 cm cystic space-occupying lesion with mixed echoes
abutting the right kidney. Contrast enhanced computerized
tomography (CECT) showed a predominantly cystic mass
arising from the upper pole of the right kidney with a small solid enhancing nodular projection on the inner wall. Thick
internal enhancing septations and multiple calcific foci were
also present in the wall. The lesion was seen to compress the
right pelvicalyceal system with moderate hydronephrosis
(Figure 1A-B). Laboratory investigations were within
normal limits. The Renal scan showed mildly impaired
right kidney function. The patient underwent a radical right
nephrectomy. On gross evaluation, a large circumscribed
cystic tumor arising from the upper pole of the kidney
partly within the renal parenchyma with extension
outside the kidney capsule was identified. The lesion was
completely cystic with a thick nodular hemorrhagic wall
(Figure 1C-D). The renal interface was well defined and
separated by a fibrous capsule (Figure 1D inset). Histology
had a characteristic trabecular and ribbon–like pattern.
The neoplastic cells had rounded regular nuclei with stippled chromatin and minimal mitotic activity (<2/10
HPF) was observed (Figure
 Click Here to Zoom |
Figure 2: A) Tumor with adjoining unremarkable renal parenchyma (H&E; x40). B) Tumor cells arranged in cords, trabeculae and
ribbons (H&E; x100). C) Monomorphic tumor cells with round uniform nuclei with speckled chromatin (inset) (H&E; x200). D) Positive
synaptophysin expression (IHC; x200). E) Positive chromogranin-A expression (IHC; x200). F) Ki-67 proliferation index <2% (IHC;
x400). |
Well-differentiated neuroendocrine tumor in the kidney
is extremely rare1. Renal NETs are usually solid and
may show a cystic component. Our case was completely
cystic with a size of 23.5 cm in diameter along with
a mural nodule, which is a rare presentation of renal
neuroendocrine tumors. The pathogenesis of renal
neuroendocrine tumors is controversial. They have been
reported to arise in congenital anomalies like polycystic
kidney disease, horseshoe kidney and mature teratoma2.
Well-differentiated neuroendocrine tumors are incidentally
detected in 25–30% of the cases. The NET in our case
was also incidentally discovered during an ultrasound of
abdomen despite its large size2. Calcification in the renal
cyst wall may occur. Metastasis is a rare event and may occur to the regional lymph nodes, liver, bone, breast, and lung3. Metastatic potential is higher in solid tumors, larger
than 4 cm, outside the renal capsule and with a mitotic rate
of more than 1/10 high power fields1. Positron emission
tomography (PET-CT) and octreotide scintigraphy
are useful for diagnosis, staging, and monitoring after
treatment for the development of recurrence or metastasis
of neuroendocrine tumors4.
Well-differentiated neuroendocrine tumors should be
considered in the differential diagnosis of predominantly
cystic lesions in the kidney. Other lesions presenting as
renal cysts include clear cell renal cell carcinoma (RCC),
especially in cases with low nuclear grades, papillary RCC,
chromophobe RCC, collecting duct carcinoma, or even
oncocytoma and they may all occasionally demonstrate
focal to extensive cystic formation. Simple benign cysts
are commonest and may become complicated in case of
hemorrhage, infection and ischemia. On radioimaging,
cystic NET tends to be hypodense, does not usually enhance
in arterial phases and may show calcification. Large size
and extrarenal extension herald metastatic potential despite
low-grade morphology and such patients should undergo
rigorous oncologic surveillance after nephrectomy. |
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Introduction
References
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1) Mardi K, Negi L, Srivastava S. Well differentiated neuroendocrine
tumor of the kidney: Report of a rare case with review of literature.
Indian J Pathol Microbiol. 2017;60:105-7.
2) Romero FR, Rais-Bahrami S, Permpongkosol S, Fine SW,
Kohanim S, Jarrett TW. Primary carcinoid tumors of the kidney. J
Urol. 2006; 176:2359-66.
3) Ouyang B, Ma X, Yan H, He J, Xia C, Yu H. Renal carcinoid tumor
with liver metastasis followed up postoperatively for 9 years.
Diagn Pathol. 2015;10:182.
4) Tanaka T, Yamamoto H, Imai A, Shingo H, Yoneyama T, Koie
T, Hashimoto Y, Ohyama C. A case of primary renal carcinoid
tumor. Case Rep Urol. 2015;736213. |
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Introduction
References
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