|Year : 2022 | Volume
| Issue : 4 | Page : 605-608
Congenital mesoblastic nephroma beyond infancy
Priya Dhandore, Narendra Narayan Hombalkar, Mohd Hamid Shafique Ahmed Khan
Department of Surgery, Government Medical College, Miraj, Maharashtra, India
|Date of Submission||30-Jun-2020|
|Date of Decision||15-Sep-2020|
|Date of Acceptance||02-Dec-2020|
|Date of Web Publication||24-Jun-2021|
Mohd Hamid Shafique Ahmed Khan
Department of Surgery, Government Medical College, Miraj - 416 416, Maharashtra
Source of Support: None, Conflict of Interest: None
Congenital mesoblastic nephroma (CMN) is a peculiar renal tumor with a unique clinical, therapeutic, and prognostic pattern. CMN is a benign renal tumor of the neonatal period and early infancy. Although a rarity, presentations beyond infancy are also reported. Rarely, this tumor presents beyond infancy. The case report tries to highlight the fact that this tumor though rare beyond infancy should also be included in the list of differentials of childhood renal masses. It also underlines the utility of preoperative biopsy and the role of nephron-sparing surgery while dealing with such a benign etiology (considering the excellent prognosis associated with the condition).
Keywords: Adult, congenital mesoblastic nephroma, infancy
|How to cite this article:|
Dhandore P, Hombalkar NN, Shafique Ahmed Khan MH. Congenital mesoblastic nephroma beyond infancy. Med J DY Patil Vidyapeeth 2022;15:605-8
| Introduction|| |
Congenital mesoblastic nephroma (CMN) was first described by Bolende et al. in 1967. It is a rare tumor beyond infancy. It can be treated successfully by complete excision without a need for adjuvant chemotherapy or radiotherapy. A good prognosis is a rule in such tumors irrespective of the age of presentation.
| Case Report|| |
A 4-year-old boy was admitted to our hospital with right-sided renal mass. The child had no associated symptom except for the mass which was incidentally noticed by the parents. There was no history of hematuria, hypertension, weight loss, or any associated anomalies. The past history was not contributory, and there was no history of any similar mass in the family. The child was thriving well and had normal mental development. The general examination did not reveal anything significant except for pallor. There was no hemihypertrophy, macroglossia, the posterior helical indentation of ear pinna, or umbilical anomaly. Clinically, it was a solid right-sided renal mass that was ballotable and moving well with respiration, about 8 cm in diameter. Abdominal contrast-enhanced computed tomography (CECT) confirmed a large tumor mass 12 cm × 10 cm in dimensions which was fairly well-encapsulated located at the inter-polar and lower polar region of the right kidney on the posterolateral aspect, pushing the remaining kidney anteriorly. The tumor showed poor contrast enhancement on intravenous contrast injection. The lower and middle calyces of the right kidney appeared distorted, and the upper calyx was dilated. Right renal function was preserved. The left kidney was normal with an intact collecting system and a good function. Enlarged lymph nodes were not detectable. No free fluid was seen in the abdomen. The liver, spleen, aorta, and inferior vena cava appeared normal. Radiographs of the chest showed no neoplastic spread. Considering the radiological diagnosis and the clinical presentation, the decision was made to go for exploratory laparotomy with right nephroureterectomy. The tumor was easily excisable with no local extension/tumor spillage [Figure 1]. There were no enlarged lymph nodes or ascites.
Histopathological examination of the surgical specimen revealed a sheet-like proliferation of plump, atypical spindle cell with abundant cytoplasm, vesicular nuclei, and nucleoli. The background shows necrosis. Impression – cellular variant of CMN [Figure 2].
|Figure 2: Microscopic examination (H and E) showing cellular variant of congenital mesoblastic nephroma|
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| Discussion|| |
CMN accounts for approximately 5% of all tumors in childhood. The most common clinical presentation is a palpable abdominal mass, with hematuria occurring less frequently. The Societe Internationale D'oncologie Pediatrique (SIOP) classifies CMN as a “low-risk tumor.” Nephrectomy alone is usually a sufficient treatment, and chemotherapy is not routinely justified. Complete surgical resection remains the most important prognostic factor. Only 5% of the patients have a recurrence; therefore, during the 1st year after the nephrectomy, the patient must be submitted to a series of ultrasonographic assessments to detect the early signs of local recurrence., It is a mesenchymal tumor. Macroscopically, the tumor is a solid un-encapsulated mass that often occurs near the renal hilum. Histologically, it is typically composed of connective tissue growing between nephrons, usually replacing most of the renal parenchyma. There are two main pathological variants: Classic mesoblastic nephroma: Accounts for less than one-third of cases of CMN. Cellular mesoblastic nephroma variant may exhibit aggressive behavior including vascular encasement and metastasis. Another variant is mixed type.
It is predominantly seen in early infancy and indeed is uncommon among patients older than 1 year of age. The tumor is the most common fetal renal neoplasm and is usually diagnosed exclusively during the perinatal period or in early infancy. After the 1st year of life, Wilm's tumor is the most common kidney tumor of childhood. This differing age incidence should permit the segregation of the tumors on clinical grounds with reasonable certainty. It has become a thumb rule in clinical practice that Wilm's is a rarity till 1 year and it is exclusive after 1 year. Our case refutes this rule. Mesoblastic nephroma occurrence beyond infancy is a rarity, but it cannot be said to be exclusively absent. The ages in the early SIOP study ranged from new-born to 22 months, but only five children were older than 4 months, whereas the mean age in the NWTS study was 3.4 months with the eldest being 32 months. CMNs have been reported in adult patients by various authors as anecdotal reports, but only 18 such cases had been reported in the English literature. This fact gains more weight when we consider the prognosis of MN which is far better than Wilm's tumor which is the closest differential. The need for adjuvant therapy is also absent in the case of MN. Considering all these facts, we opine that MN should be considered in the differential diagnoses of a renal mass presenting beyond infancy.
To conclude the discussion, the following are the various differential diagnoses (clinical and pathological) of CMN with a brief description.
- Clear cell sarcoma: Kidd recognized it as a separate clinicopathological entity in 1970. It comprises 4% of all renal tumors in children. The median age of presentation is 2–3 years of age with male preponderance (male:female = 2:1). Abdominal distension and hematuria are the most common presenting clinical features, microscopy shows an admixture of cord cells, septal cells, stromal fragments, myxoid materials, and blood vessel, which is positive for vimentin., Nephrectomy with adjuvant chemotherapy with vincristine, doxorubicin, and dactinomycin is recommended treatment
- Malignant rhabdoid tumor: Less than 0.5 per million per year children suffer from. Median age between 10 and 18 months with equal incidence in both the gender. Presenting clinical features are abdominal mass, hematuria, fever, hypertension, and anemia. Malignant rhabdoid tumor is characterized by a solid proliferation of tumor cells with vesicular nuclei and prominent nucleoli, abundant eosinophilic cytoplasm. It is positive for vimentin and negative for actin, myosin, desmin, PAS, and cytokeratin., Nephrectomy with adjuvant chemotherapy is the treatment of choice
- Metanephric stromal tumor: Often present with pain and hematuria. The median age of presentation is 13 month. Being a benign tumor, nephrectomy is the treatment of choice
- Rhabdomyosarcoma: Usually, patients present with large tumors and may have metastasis. The median age of the presentation is 6 years. Microscopically has three variant embryonal, alveolar, and pleomorphic. They are positive for desmin, myoglobin, and myogenic. Radical nephrectomy is the treatment of choice
- Renal cell carcinoma (RCC): Pediatric RCC is an understudied tumor. <0.5 per million people under the age of 19 years suffer from. The Median age of presentation is 10 years with equal incidence in both the gender. The histology of this tumor is distinct from adult RCC. Renshaw described this tumor with distinctive voluminous clear cytoplasm which he proposed were a newly recognized type of RCC involving translocations of Xp11. Tumor resection is the mainstay of therapy.
Other less common differential diagnoses are anaplastic renal sarcoma, primary renal synovial sarcoma, and primitive neuroectodermal tumor, etc.
| Conclusion|| |
Although CMN is a disease of early infancy, rarely it can present in older children. Surgical resection alone is usually curative. This case report tries to highlight the fact that this tumor though rare beyond infancy should also be included in the list of differentials of childhood renal masses. It also underlines the utility of preoperative biopsy and the role of nephron-sparing surgery while dealing with such a benign etiology (considering the excellent prognosis associated with the condition).
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 1], [Figure 2]