Introduction
Multilocular cystic nephroma (MLCN) has been described as a slow-growing rare benign renal tumor. It is grouped under the mixed epithelial-stromal tumor of the kidney in the World Health Organization classification of renal neoplasms. It usually presents as a localized, solitary, multicystic lesion in the kidney. The histogenesis of the lesion was controversial; in its early stages, few believed that it is of developmental origin with malignant potential. Later they were reported as benign mixed tumors arising in the renal parenchyma. It shows bimodal distribution seen in both children and adults.
What Is Multilocular Cystic Nephroma?
It is a rare benign mixed tumor of epithelial and mesenchymal origin. Different terminologies have been given to this neoplasm, such as polycystic nephroblastoma, well-differentiated polycystic Wilms tumor, Perlman tumor, and differentiated nephroblastoma.
Who Described Multilocular Cystic Nephroma?
Multilocular cystic nephroma (MLCN) was first described in the year 1892. Boggs and Kimmelsteil first described the neoplastic nature of this lesion in 1956. Later Joshi and Beckwith emphasized a neoplastic nature of the lesion rather than a developmental or hamartomatous origin.
What Is the Epidemiology of Multilocular Cystic Nephroma?
Studies report that MLCN shows a bimodal distribution, seen in children younger than two years and middle-aged adults over 30 years of age. Found to be more prevalent among male children and women of postmenopausal age. It is frequently reported in the lower pole of the kidney.
More than 200 cases of MLCN have been reported so far in the literature.
What Is the Cell of Origin of Multilocular Cystic Nephroma?
Multilocular cystic nephroma is a mixed tumor that shows the proliferation of cells from epithelial and mesenchymal origin.
What Are the Two Types of Lesions Categorized Under Multilocular Cystic Nephroma?
The two types of lesions with the same clinical and radiographic presentation but with different histological features are lumped under the same terminology; multilocular cystic nephroma, which includes,
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Cystic Nephroma - Is purely cystic lined by epithelium and underlying fibrous septa containing matured tubules.
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Cystic Partially Differentiated Nephroblastoma (CPDN) - This shows cystic features such as cystic nephroma, but in addition, connective tissue septa show foci of blastemal cells.
What Is the Etiology of Multilocular Cystic Nephroma?
The exact etiology of MLCN is unclear. Few studies report the association between genetic, hormonal, and oncogenic factors in the occurrence of MLCN, which needs to be documented. Research states that germline mutation of DICER1 is associated with the occurrence of familial cystic nephroma.
What Are the Clinical Features of Multilocular Cystic Nephroma?
The clinical manifestations of MLCN differ in children and adults. In children, it manifests mostly as a painless abdominal mass with no other related symptoms. In adults, it presents nonspecific clinical symptoms such as,
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Abdominal pain.
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Loin pain.
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Hematuria - Blood in the urine.
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Urinary tract infection.
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Hypertension etc.
How Is Multilocular Cystic Nephroma Diagnosed?
The steps in the diagnosis of MLCN include,
Clinical Examination: Clinical examination reveals a palpable abdominal mass with the associated symptoms.
Radiological Diagnosis:
- Plain Radiograph - This may suggest the presence of a large abdominal mass displacing the loops of the kidney.
- Ultrasound Examination - This may reveal a multilocular cystic mass, and vascularity of the septa may be noted. The cystic contents may show low-level echoes.
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Computerized Tomography Scan (CT) - This may reveal multilocular cystic mass often protruding into the renal pelvis with variable septal enhancement. Associated streakiness in perirenal fat is noted.
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Magnetic Resonance Imaging (MRI) - Capsulated multilocular cyst and the septa appear hypointense with the contents of the cyst showing hyperintensity in T2 weighted images. But the intensity appears to be variable in T1 weighted images, possibly because of the different concentrations of protein or blood products in the cyst.
What Are the Radiological Differential Diagnosis of Multilocular Cystic Nephroma?
Because of the multilocular cystic appearance, it should be differentiated from the following conditions,
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Multicystic Dysplastic Kidney - It is a developmental disturbance of the kidney characterized by multiple cysts in the kidneys resembling a bunch of grapes.
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Multilocular Renal Cell Carcinoma - This is a rare malignant tumor with cystic and clear cell features affecting the kidneys.
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Tubulocystic Carcinoma - This is a very rare subtype of renal cell carcinoma characterized by the presence of closely packed tubules and numerous cysts of variable size.
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Medullary Sponge Kidney - This is a congenital disorder of the kidneys characterized by the formation of small cysts in the organelles of the kidney.
What Is the Gross Appearance of Multilocular Cystic Nephroma?
The gross findings reveal a well-circumscribed mass that contains multilocular fluid-filled cystic compartments separated by thin translucent septa. The entire mass is covered by a thick fibrous capsule.
What Are the Histopathological Features of Multilocular Cystic Nephroma?
A microscopic examination of the mass would reveal the cuboidal or the flattened cells lining the cystic epithelium. In a few areas, the eosinophilic cuboidal cells protrude into the lumen producing a hobnail or teardrop appearance. The underlying connective tissue septa show matured tubules. In the case of cystic partially differentiated nephroblastoma (CPDN), there will be foci of blastemal cells in the stroma along with matured tubules.
What Is the Immunohistochemical Finding of Multilocular Cystic Nephroma?
The immunohistochemical findings may show positive expression for CK7 (cytokeratin 7) and CK19 (cytokeratin 19) in the lining epithelium, suggesting renal tubular differentiation. The underlying stroma would show positive for estrogen receptor (ER) and progesterone receptor (PR).
How Is Multilocular Cystic Nephroma Managed?
In case of localized, solitary, unilateral lesions measuring less than four centimeters, partial nephrectomy by conventional or laparoscopic surgical method would help preserve the renal tissues and function. Other less invasive treatment alternatives include cryoablation and radiofrequency ablation techniques to remove the small renal lesions without affecting kidney function. In the case of bilateral, multiple lesions measuring more than four centimeters, radical nephrectomy is the standard treatment.
What Is the Prognosis of Multilocular Cystic Nephroma?
Since it is a benign condition, the prognosis is reported to be good with prompt treatment and complete removal of the tumor from the kidney.
Is Follow-up Needed in Multilocular Cystic Nephroma?
Though it shows a good prognosis after treatment, regular follow-up is necessary as cases of recurrence have been reported in the literature.
Conclusion
Multilocular cystic nephroma is a rare benign neoplasm with unknown etiology and pathogenesis. It shows sweeping clinical features, and radiological findings also coincide with multiple renal disorders because of its multilocular cystic appearance. Histopathological findings help in the confirmatory diagnosis of the condition. The prognosis is reported to be good with appropriate treatment. Follow-up is needed to prevent the recurrence of this neoplastic entity.
