jhc-2019-jul-v-3-n-2-multilocular-islam-f

Case Report

Multilocular Cystic Nephroma in an Adult Patient: A Case Report

*Islam F,1 Begum A,2 Kamal M3

 

  1. *Dr. Farhana Islam, Assistant Professor, Department of Pathology, Popular Medical College, Dhaka. ifarhana2006@gmail.com
  2. Afroza Begum, Associate Professor, Department of Pathology, Anwer Khan Modern Medical College, Dhaka.
  3. Mohammed Kamal, Professor of Pathology, BSMMU, Dhaka.

 

*For correspondence

 Abstract

Multilocularcystic nephroma is relative rare, cystic neoplasm of the kidney and is usually benign. There are two peaks in the incidence of the tumor, with a bimodal distribution presenting in the first 2 to 4 years of life, and again in 40 to 60 years.They are usually incidentally found as an asymptomatic abdominal mass. Radiologically, it is difficult to differentiate between cystic nephroma and cystic RCC in adults. The exact diagnosis primarily depends on the histopathologic examination. We present a 35-year-old male patient with a palpable mass over the right upper quadrant of the abdomen, which was gradually increasing in size. A Right sided  nephrectomywas performed on thispatient. Microscopically, the tumor composed of variable-sized cysts lined by a layer of flattened or cuboidal cells thatconfirmed a diagnosis of Multilocular cystic nephroma.

[Journal of Histopathology and Cytopathology, 2019 Jul; 3 (2):167-171]

 Key words: Multilocular cystic nephroma, Kidney, Benign renal tumor

Introduction

Multilocular cystic nephroma (MLCN) is a rare, benign cystic neoplasm of the kidney. It was first described in 1892 as cystic adenoma of the kidney and over 200 cases have been reported in the literature so far.1 MLCN is an uncommon, benign cystic lesion of the kidney with bimodal age distribution, occurring in both infants and adult population. Although it has been described in neonates, MLCN is more commonly seen in the age group of 2–4 years (of which 73% are in males). Below 4 years of age, male to female ratio is 3:1 and boys are affected more than girls. In adults, it is seen in the 4th–6th decade with its male to female ratio being 1:8.2 The main complaint in children is abdominal mass, while in symptomatic adults predominant complaints are abdominal distension, and pain, recurrent urinary system infection, and hematuria.3 However, most of the patients with cystic nephroma are asymptomatic and usually found incidentally. Herein, we present a case of a 35-year-old male whodeveloped a multilocular cystic nephroma in the upperpole of the right kidney. The clinicalpresentation, radiological findings, and histopathologic results werereported and the literature was reviewed.

Case Report

Our case a 35 years old male was suffering from lower back pain for 4 years. He did not pay attention to it until he discovered a palpable mass over the right upper quadrant of the abdomen, which was gradually increasing in size. Routine laboratory examinations were all within normal limits. Abdominal ultrasonography showed right renal cystic mass including a cluster of variable-sized cysts separated by hyperechoic tissue at the upper pole of the right kidney (Fig-1). I.V.U was done and the report suggested of mass in right kidney possibly cyst. Both the kidneys were normal functioning (Fig-2) MRI report suggested a right cystic renal mass (stage-II, Fig-3). Right sided  nephrectomy was done. Specimen of kidney with part of right ureter and peri-nephric fat was sent for histopathological examination on March 2010.

 Nephrectomy specimen with part of perinephric fat measured (14x9x6) cm. Cut surface showed multilocular cystic growth measured 9 cm in maximum  diameter involving  whole upper pole and mid portion of the kidney. The largest locule of the cyst measured 3 cm in maximum diameter. The wall of these cysts were thin and the locules contained straw colored watery fluid. Adjacent parenchyma was normal(Fig-4).

Microscopically, the tumor was composed of variable-sized cysts separated by fibrous septa. The cyst wall was partly lined by flattened epithelium and partly by cuboidal epithelium. The stromal septae was made of dense fibrous connective tissue with scattered smooth muscles. No nephron elements were found in the stromal septa. No communication among locules was noted. Kidney tissue surrounding the growth showed no significant change (Fig-5,6,7). A multilocular cystic nephromawas diagnosed on the basis of this  histopathological findings.

No postoperative complication was encountered and the patient was discharged uneventfully 7 days after the surgical procedure. No recurrence was found during 3 years of follow-up.

Discussion

MLCN has at least 20–25 synonyms, which include multilocular cystic renal tumor, benign multilocular cystic nephroma, polycystic nephroblastoma, and so on. Its etiology and histogenesis is debatable, and in the past they were considered to be developmental lesions with malignant potential. According to the World Health Organization (WHO) classification of renal neoplasms, MCN is grouped with the mixed epithelial and stromal tumors (MEST). The term renal epithelial and stromal tumor (REST) can be used to encompass both MCN and MEST.2

Cystic nephroma has a special bimodal age distribution, one in childhood of 2 to 4 years of life, predominantly in boys, and the other in the 40 to 60 years of life. The disease is predominantly found in adult female with an 8-time prevalence compared to male. Similar to other renal tumors, classical signs can include palpable abdominal mass, abdominal pain, and gross hematuria. However, most of cystic nephroma were found incidentally and asymptomatically.4

Usual ultrasonographic findings are multiple hypoechoic spaces separated by thin septa. CT scan, on the other hand, usuallyreveals a multilocular cystic tumor with curvilinear calcifications. Herniation into the renal collecting system with septal enhancement is commonly seen.3 Although in our case the patient done Magnetic Resonance Imaging (MRI) but it is rarely indicated. Imaging features include usually hypointense signal on T1-weighted sequences (although this may vary) and hyperintense signal on T2-weighted sequences. Septa are usually hypointense on all sequences due to fibrous content.2

Unfortunately, it is pretty difficult to differentiate between cystic nephroma, cystic RCC in adults and Wilms tumor in children radiologically even on CT scan.5 Since definitive discrimination is not possible via radiologi­cal means, histopathological diagnosis is required for dif­ferential diagnosis.

Grossly, cystic nephroma is a well-circumscribed tumor with a smooth surface. The cut surface reveals variable-sized cysts separated by thin septa. The cysts contain mostly clear to yellowish fluid but occasionally dark-colored fluid because of blood clots retention. They may be herniated into the renal collecting system but do not communicate with renal pelvis. That is why only parts of patients have hematuria microscopically or macroscopically. Bilateral cystic nephroma and recurrence after excision was rarely reported. Only several case reports in childhood co-existing with nephroblastoma.6

The criteria for pathologic diagnosis were established by Powell et al. in 19517 and later modified by Boggs and Kimmelstiel in 1959,8 and include the following (1) The lesion must be multilocular (2) The cysts must, for the most part, be lined by epithelium (3) The cysts must not communicate with the pelvis (4) The residual renal tissue should be essentially normal, except for pressure atrophy (5) No fully developed nephrons are present within the septa. Our patient fulfills all 5 criteria.

Development of cystic renal cell carcinoma originating from CN has been also reported, and postoper­ative follow-up is recommended. Local recurrence or me­tastasis is limited to a few cases, and it has been reported that local recurrence especially in patients who underwent partial nephrectomy is a possibility which might be re­lated with incomplete resection.3 Contrarily, Castillo et al.9 presented a series of 29 cases, and couldn’t encounter any postoperative local recurrence or metastasis. Also in our case we didn’t observe any local recurrence or metas­tasis,after 3years of  postoper­ative follow-up.

Traditionally, treatment for any solid renal mass or multilocular cystic lesion was nephrectomy. Nowadays, partial nephrectomy has become the initial standard option for small renal mass.10 If the lesion is localized enough, excision of the lesion or partial nephrectomy can be considered, even for large tumor in children.11

Conclusion

Cystic nephroma is a rare, benign renal tumor, which progresses with a silent course, and demonstrates a bimodal age distribution, and it is difficult to differentiate from cystic RCC. Neither clinical signs nor radiological findings can obtain a pre-operative diagnosis of MLCN. Surgical intervention and histopathologicexamination are necessary for the final diagnosis. Noninvasively radiological follow-up is recommended after complete resection.

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