Asymptomatic Infantile Cystic Nephroma: A Diagnostic Dilemma

Abstract

Cystic nephroma, also called multilocular cystic nephroma, is a relatively rare, nongenetic, benign, unilateral, renal multicystic lesion. The non-specific clinical findings and the poor contribution of imaging examinations make the preoperative diagnostic dilemma from other cystic renal neoplasia; thus nephrectomy seems to be the most preferable treatment. We report a case of cystic nephroma in 11 months old male child presented with asymptomatic lump in abdomen. After a series of examinations including abdominal ultrasound, intravenous pylography and computed tomography, he underwent radical nephrectomy and diagnosis is confirmed on histopathology.

Introduction

Cystic nephroma is a rare, non-genetic, benign, unilateral, renal multicystic lesion; grouped along the mixed epithelial-stromal tumour of the kidney [1]. There is no proved theory concerning its pathogenesis, [2] thus its origin is designated as being dysplastic/hamartomous/neoplastic. The usual presentation is benign clinical course with bimodal age distribution, asymptomatic abdominal mass, with non-specific symptoms as abdominal pain, hematuria, and urinary tract infection [3].

Case

An 11-month-male infant presented with asymptomatic right abdominal mass discovered by his mother, without any history of urinary or bowel complaints, fever, pain in abdomen or vomiting. General examination was unremarkable. On examination, 10 × 10 cm retroperitoneal mass was felt in right hypochondrium and lumbar regions. It was smooth surfaced, firm to hard with restricted mobility, palpable bimanually and right renal angle fullness was present. Ultrasonography revealed a well defined, rounded, avascular, multilocular cystic retroperitoneal mass in the renal area with non visualisation of right kidney (Fig. 1a-b). IVP suggested a non-functioning right with normal functioning left kidney. CT abdomen confirmed the findings making radiological impression of dysplastic cystic right kidney or cystic neoplasm of kidney without lymphadenopathy and metastatic disease (Fig. 1c-d).

Fig. 1.

Radiographic evaluation: (a-b) Ultrasonography, (c-d) CT Abdomen

A radical nephrectomy was carried out with dilemma of cystic Wilm’s tumour as common in this age. Grossly, the surface was unremarkable (Fig. 2a) while the cut surface revealed numerous cysts of varied size of 2-3 cm each, non-communicating and filled with serous fluid, without solid components. The capsule and septa were composed of dense fibrotic tissues. The renal parenchyma was only minimally present at lower pole; the pelvicalyceal system was dilated in remnant (Fig. 2b).

Fig. 2.

Specimen after nephrectomy (a) Unremarkable renal surface with herniated pelvis and arrow showing ureter (b) Cut surface showing numerous cysts containing serous fluid

Microscopically, multiple cysts were lined by flat cuboidal epithelial cells arranged in a hobnailed pattern, and the intervening stroma is nondescript, fibrocollagenous (Fig. 3a-b). Postoperative period was uneventful.

Fig. 3.

Histopathological microphotograph of cystic nephroma (a)10× zoom (b)40× zoom

Discussion

Edmunds reported the first case of CN in 1892 as cystic adenoma of the kidney [2]. There have been fewer than 200 cases reported in the literature [3]. It could be both congenital, affecting predominantly infant males, as well as acquired affecting postmenopausal females [4, 5], Generally, it is malformation enlarged by fluid accumulation and cystic dilatation of individual locules and present as tumour-like cystic mass. Powell et al establishes criteria for pathological diagnosis and later modified by Boggs and Kimmelstiel, and include the following; lesion must be multilocular, cysts must be lined by flattened, cuboidal, or hobnail epithelium, cyst must not communicate with the pelvis, residual renal tissue should be essentially normal, except for pressure atrophy and no fully developed nephrons are present within the septa. Our patient fulfils 4 criteria [6].

Cystic nephroma presents with no-specific imaging findings as well [2]. Plain radiographs may show a mass, rarely with calcification. The excretory urogram demonstrates a well-defined, intra-renal mass in a normal functioning kidney; delayed excretion with hydro-calycosis or no visualization in obstruction by pelvic herniation of the tumour. Sonographic findings relate to the size of the locules; either a non-specific complex intra-renal mass or mass with multilocular configuration, discrete septa and sono-lucent spaces. Computed tomography usually reveals a smooth multilocular mass and determines its perinephric extend. Color-doppler flow imaging shows a relatively hypovascular and less commonly shows avascular mass. MRI angiography is an alternative. At present there is no reliable clinical or radiographic means to differentiate cystic nephroma from cystic Wilm’s tumour in children or RCC in adults [7].

The non-specific clinical findings and the poor contribution of imaging examinations render the exact preoperative distinction from other cystic renal neoplasia difficult [1–3]. Cystic nephroma, cystic partially differentiated nephroblastoma and cystic Wilms’ tumor are a spectrum with benign to malignant end respectively [7]. Thus, taking into consideration the possible neoplastic nature and the difficulty in preoperative diagnosis, surgical excision of the tumour, radical nephrectomy, is strongly advised for definite diagnosis and treatment [7, 8]. Nephron sparing surgery can be the therapy of choice where the lesion is well encapsulated and where the benign nature of the cyst is not doubtful.

Conclusion

The non-specific clinical findings and the poor contribution of imaging examinations make the preoperative diagnostic dilemma from other cystic renal neoplasia; nephrectomy seems to be the most preferable treatment. Final diagnosis can be established in the histopathological examination of the completely rejected tumour in the pathology laboratory.