Year : 2010 | Volume
: 21 | Issue : 3 | Page : 518--520
Cystic nephroma: A diagnostic dilemma
Debajyoti Mohanty, Bhupendra Kumar Jain, Vivek Agrawal, Arun Gupta
Department of Surgery, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi, India
Bhupendra Kumar Jain
Department of Surgery, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi
Cystic nephroma (CN) is a rare benign neoplasm of kidney with excellent prognosis. An accurate pre-operative diagnosis differentiating CN from other cystic renal malignancies may be impossible by clinical and radiological examination, and histopathological examination provides the final diagnosis. This report describes two adult patients with large multi-locular cystic renal masses on imaging and the diagnosis of CN was clinched post-operatively by the honeycomb appearance of the cut specimen and the finding of multiple, non-communicating fluid filled cysts lined by cuboidal or flattened epithelial cells and absence of blastemal cells on microscopy. Tumor diameter on cross sectional imaging remains the key parameter for treatment decisions in renal neoplasms, with nephrectomy being preferred for larger lesions.
|How to cite this article:|
Mohanty D, Jain BK, Agrawal V, Gupta A. Cystic nephroma: A diagnostic dilemma.Saudi J Kidney Dis Transpl 2010;21:518-520
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Mohanty D, Jain BK, Agrawal V, Gupta A. Cystic nephroma: A diagnostic dilemma. Saudi J Kidney Dis Transpl [serial online] 2010 [cited 2020 Jul 16 ];21:518-520
Available from: http://www.sjkdt.org/text.asp?2010/21/3/518/62699
Multilocular cyst of the kidney or cystic nephroma (CN) is a rare and benign non-familial renal neoplasm with an excellent prognosis. These tumors may be amenable to renal sparing surgery but most patients undergo nephrectomy in absence of an accurate pre-operative diagnosis. We herewith report two adult patients with CN to highlight the diagnostic dilemma and management options for this rare tumor.
A 45-year-old lady presented with complaints of intermittent, non-colicky pain in right hypochondrium and lumbar region of 12-months duration. Abdominal examination was normal. Ultrasonogram (USG) of the abdomen showed a multi-septate cystic mass measuring 6.5 Χ 5.5 Χ 4.3 cm involving the mid-pole of the right kidney and cholelithiasis. Contrast enhanced computed tomogram (CECT) of the abdomen showed a 6.6 Χ 6.5 Χ 4.4 cm cystic mass with fine internal septations and delayed enhancement of the wall, involving the midpole of the right kidney compressing the pelvis and upper ureter [Figure 1]. Urine cytology for malignant cells was negative. Hydatid serology was within normal range. Right nephrectomy and cholecystectomy was performed. The cut section of kidney showed a large cyst containing clear fluid with multiple small cystic swellings arising from the wall. The patient was asymptomatic on follow-up after six months.
A 25-year-old lady presented with persistent dull aching pain in the right lumbar region for six months with no urinary complaints. Abdominal examination revealed a non-tender, smooth, well defined, rounded lump in the right upper abdomen, that moved with respiration and the upper margin was not reachable. USG of the abdomen showed a multi-septate cystic exophytic mass measuring 6 Χ 5.4 Χ 4.7 cm involving the upper and mid-poles of the enlarged right kidney. CECT scan of the abdomen revealed a non-enhancing multi-locular cystic mass involving upper pole of the right kidney extending into the middle part, measuring 6.5 Χ 6.0 Χ 4.2 cm with no solid component. No vascular invasion, ascites or lymphadenopathy was seen. Urine cytology for malignant cells was negative. Per-operatively, a right renal mass was seen with bosselated surface involving more than upper 2/3 rd of the kidney, with no infiltration of the Gerota's fascia and no enlarged lymph nodes. A radical nephrectomy was done. The cut surface of the specimen showed multiple cystic spaces, filled with clear fluid like a honeycomb; no solid component was seen [Figure 2]. The patient was well on follow-up after 18 months.
Cystic nephroma was the histopathological diagnosis in both the patients.
Microscopically, CN is characterized by well demarcated, multiple, non-communicating fluid filled cysts lined by cuboidal or flattened epithetlial cells, separated by septations and absence of blastemal cells. It has a bimodal distribution with two-thirds of tumors presenting in children between three months and two years, with male predominance and second peak in adults over 30-years of age, with a female predominance. Only 5% of this rare tumor is seen in the 5-30 years age-group. 
CN is considered to be a segmental form of renal dysplasia related to polycystic kidney disease or maldevelopment of the ureteric bud. It is also regarded as a neoplasm, occurring at the benign end of the wide spectrum of a continuum of renal tumors with cystic variant of Wilms' tumor at the other extreme and cystic partially differentiated nephroblastoma (CPDN) occupying the middle zone. 
Flank pain, hematuria, hypertension and urinary tract infection are the usual presenting features in adults,  while painless abdominal mass is common in children. The CECT and magnetic resonance imaging findings suggestive of CN are encapsulated multi-locular cystic renal mass with contrast enhancement of septae.  Precise pre-operative diagnosis of CN by clinical and radiological means may be impossible and the final diagnosis is made by surgical excision and histopathological examination.  We did not attempt fine needle aspiration cytology as the cysts are non-communicating and multi-locular resulting in difficulty to obtain adequate tissue for diagnosis.  The differential diagnosis includes CPDN, Wilms' tumor with multi cystic changes, and cystic hamartoma of the renal pelvis, clear cell sarcoma, and multi cystic renal cell carcinoma.
Since there is a wide array of differential diagnosis, to rule out malignancy convincingly is not easy, and the tumor diameter on cross sectional imaging remains the key parameter for treatment decisions. The aggressive potential of small renal cell carcinoma (RCC) in terms of tumor grading and staging increases dramatically beyond a tumor diameter of 3 cm.  Nephron sparing surgery can be attempted in CN when the renal mass is  and close followup with USG or CECT scan is possible. Recurrence has been reported following in-complete excision and partial nephrectomy.  Nephrectomy should be considered for larger lesions and radical nephrectomy, as done in the second case, is indicated if possibility of RCC cannot be excluded.
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