Renin in mesoblastic nephroma: an immunohistochemical study

Congenital mesoblastic nephroma 50 years after its recognition: A narrative review

Congenital mesoblastic nephroma (CMN) is a rare pediatric renal tumor with low malignant potential that most commonly occurs early in infancy. Treatment strategies are based on the few published CMN series, while a significant number of CMN patients have been described in case reports. The aim of this narrative review was to create an up-to-date overview of the literature. Complete surgical removal is curative in most cases. The risk of treatment-related mortality (both surgery- and chemotherapy-related) is relatively high in the first weeks of life, indicating that these young patients deserve special attention with respect to timing and type of treatment.

Renal and hepatic tumors in the neonatal period

Renal and hepatic tumors in neonates are extremely rare. Nevertheless it is important for clinicians to be familiar with them. Both renal and hepatic neonatal tumors are heterogeneous collections of several tumor types. Some renal and hepatic tumors are benign and may require no interventions whereas others can be associated with significant morbidity and even mortality and may require multimodality treatment. Early diagnosis and initiation of the proper treatment plan is crucial for achieving the best outcomes for these rare tumors in this vulnerable population.

[Kidney tumors in childhood]

Types of renal tumors arising in children are different from those occurring in adults. Nephroblastoma is the most common (85%) with a clinical outcome which has dramatically improved in the last 30 years. Current classifications are aimed at better adaptation of treatment to each individual case, reducing iatrogenic complications without impairing total cure. Amongst entities which have been recently described or are better known we can find juvenile carcinoma associated with Xp11.2 translocation, renal medullary carcinoma, metanephric tumors, etc. Role of molecular cytogenetics is increasing for classification (and treatment) and this should always be kept in mind when dealing a fresh specimen of childhood renal tumor.

Non-Wilms' renal tumors in children

Renal tumors other than Wilms' tumors are infrequent in childhood. Wilms' tumors account for 6% to 7% of childhood cancer, whereas the remaining renal tumors account for less than 1%. The most common non-Wilms' tumors are clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, renal cell carcinoma, mesoblastic nephroma, and multilocular cystic nephroma. Collectively, these tumors account for less than 10% of the primary renal neoplasms in childhood.

Congenital mesoblastic nephroma: report of a Case with review of the most significant literature

AIMS AND BACKGROUND

Congenital mesoblastic nephroma (CMN) is a rare pediatric tumor of the kidney with the highest peak of incidence during the first 3 postnatal months. It has previously been confused with Wilms' tumor (which, on the contrary, is rare during the first six months of age and is still considered a histogenetic congener). CMN almost always has a favourable prognosis. Therefore, CMN needs to be correctly diagnosed and differentiated from other pediatric renal neoplasms. Two morphological subtypes are currently distinguished histologically: the classical or leiomyomatous type and the atypical or cellular type. Mixed forms with a combination of the two patterns are also on record. Recurrence and even tumor-related death have been described in the literature and always related to the atypical form or to the mixed form, particularly in patients aged more than 3 months and in those cases in which the surgical removal was not complete. Opinions concerning post-surgical clinical management, especially in regard to adjuvant therapy, are not unanimous.

METHODS

A case of CMN, predominantly of the classical histological subtype diagnosed in a baby with a follow-up of 6 years, is herein presented. The tumor was discovered at birth and surgically removed after one month. Since the tumor showed a high mitotic index (one of the characteristics of the cellular subtype) and the perirenal fat was focally involved with the tumor, the possibility of giving adjuvant chemotherapy was considered. Flow cytometric analysis was also performed which showed a diploid DNA content of neoplastic cells.

RESULTS

The tumor was completely removed, surgical margins were free histologically, and no clear-cut histological features of the atypical subtype were noted. Flow cytometrically, it showed the euploid DNA content. Consequently no additional therapy was given. Six years after surgery the patient is developing well and is free of disease. He has regular follow-up examinations.

CONCLUSIONS

CMN almost always pursues a benign clinical course if diagnosed under three months of age and if totally surgically excised independent of histological type. Criteria for management of atypical cases are not unanimous in regard to the benefit of additional therapy after surgery.

Plasma and renal prorenin/renin, renin mRNA, and blood pressure in Dahl salt-sensitive and salt-resistant rats

We measured plasma prorenin and renin levels, renal renin mRNA, renal anti-renin and anti-prorenin-prosequence immunoreactivity, and blood pressure in maturing Brookhaven Dahl salt-sensitive (Dahl S) and salt-resistant (Dahl R) rats during 14 days of low (0%), medium (0.4%), or high 4%) NaCl diets. Blood pressure was higher in Dahl S rats and did not increase with high NaCl. Seven-week-old Dahl R rats had twofold and sixfold higher levels of plasma prorenin and renal prosequence immunoreactivity, respectively, which by 9 weeks were the same as in Dahl S rats. The anti-renin antiserum, BR1-5, was found to detect prorenin better than renin; Dahl S rats had suppressed renal anti-renin immunoreactivity relative to Dahl-R rats. Dahl R rats were unresponsive to high NaCl, whereas in Dahl S rats, plasma renin and renal prosequence immunoreactivity fell by 90% (P < .01), renal anti-renin immunoreactivity and renal renin MRNA fell by 35% (P < .05 for both), and plasma prorenin fell by 30% (P = NS). NaCl depletion increased prorenin/renin parameters similarly in both strains. There were direct relationships among all of the prorenin/renin parameters. Between low and high salt diets in Dahl S rats, plasma renin increased 20-fold, plasma total renin (renin plus prorenin) and renal renin mRNA both increased threefold, and plasma prorenin increased twofold. The results indicate that under steady-state conditions, plasma and renal renin/prorenin parameters change concordantly and that plasma total renin (renin plus prorenin) reflects changes in renal renin mRNA. The lower blood pressure of Dahl R rats is associated with later maturation-related declines in plasma and renal prorenin. Suppression of plasma renin may delay the salt-induced blood pressure rise in Dahl S rats. Finally, the renin system and blood pressure of Dahl R rats have remarkable disregard for a high salt diet.

Wilms' tumour and hypertension: incidence and outcome

OBJECTIVE

To determine the incidence and outcome of hypertension associated with Wilms' tumour and to reduce peri-operative morbidity by appropriate treatment.

PATIENTS AND METHODS

The medical and nursing case-notes of 17 consecutive patients with Wilms' tumour treated over a 5.5 year period (1989-1994) were analysed retrospectively.

RESULTS

Ten of 17 patients had hypertension, with a mean blood pressure of 150/103 mmHg (130-220 mmHg systolic and 85-145 mmHg diastolic). There was no significant difference between the hyper- and normotensive patients in their mode of presentation. Blood pressure was stabilized preoperatively in all the hypertensive patients. Perioperative monitoring in these patients was performed using arterial and central venous pressure lines. No patient had any peri-operative hyper- or hypotensive episodes caused by handling the tumour or after nephrectomy. Thirteen patients had a favourable histological diagnosis and all the hypertensive patients were in this group. The blood pressure of all patients returned to normal within 1 month of surgery.

CONCLUSION

Both the recognition of hypertension and appropriate peri-operative treatment is mandatory for the safe surgical management of this condition.

Congenital mesoblastic nephroma: cytogenetic comparison to leiomyoma

We report the karyotype analysis of a congenital mesoblastic nephroma (CMN), a usually benign renal tumor occurring most commonly during early infancy. The tumor was composed of interlacing bundles of spindle-shaped cells and it displayed both the classic and cellular histologic patterns. Immunoperoxidase studies showed reactivity for vimentin and actin. The tumor cell karyotype included additional chromosomes 11 and an altered chromosome 12. Trisomy or tetrasomy of chromosome 11 is present in five of six reported cases and may represent a frequent alteration in the karyotype of the CMN. Furthermore, breakpoints in the q13-15 region of chromosome 12 are commonly seen in leiomyomas, which are histologically similar to the CMN. Thus, the karyotype described here illustrates another similarity between the two tumor types.

Congenital mesoblastic nephroma, nephrocalcinosis, and hypertrophic pyloric stenosis

A cellular variant of congenital mesoblastic nephroma (CMN) occurring in a newborn is presented. Coincidental findings were congenital hypertrophic pyloric stenosis (CHPS) and nephrocalcinotic hypercalcemia that reverted after nephrectomy. As of the day of writing, this multiple association has not been reported. The authors believe that both CMN and CHPS could be interpreted as fibroblastic proliferative-related entities. Transient hypercalcemia seems to be a paraneoplastic phenomenon.

Morphological and immunohistochemical characteristics of dimethylnitrosamine-induced malignant mesenchymal renal tumor in F-344 rats

Mesenchymal renal tumors in F-344 newborn rats were induced by a single dose of dimethylnitrosamine. The induced tumors were successfully transplanted into adult rats under the renal capsule. Neither the primary nor the transplanted neoplasms from various generations of grafts changed their morphological features during the tumor passage, having the same cellularity with high mitotic activity and the tendency to invade the host kidney rapidly. On the basis of lectin histochemistry and immunohistology, the tumor proved to be a mesenchymal neoplasm without any obvious capacity of the proliferating cells to differentiate into any well-known organoid element normally found in mature renal parenchyma. However, the proliferating neoplastic cells were found to have a strong vimentin positivity with desmin expression. Ultrastructurally, myofilaments with attachment bodies characteristic of smooth muscle cells were generally present in various amounts in many tumor cells. In addition, on the basis of the physiological data and on kidney/tumor renin activity obtained, it is interesting to note that the tumor-graft-invaded kidneys retained their enzyme activity, despite the obvious loss of renal tissue including glomeruli. However, the immunohistochemical findings with anti-renin antibody have clearly shown that this is not due to a renin-producing tumor but rather to the surviving (probably) non-neoplastic arterioles retaining the capacity to produce renin. Although these arterioles have mostly been found next to necrotic areas, commonly occurring in dimethylnitrosamine-induced transplantable renal tumors, the question of a possible physiological role of renin in tumor necrosis or in angiogenesis has remained open.

Congenital mesoblastic nephroma, renin production, and hypertension

Between 1964 and 1987, 12 patients with mesoblastic nephroma were treated. The BP was measured preoperatively in five patients, four of whom were hypertensive. Following nephrectomy, the BP returned to normal. Plasma renin levels were measured in one patient; they were markedly elevated pre-operatively, but returned to normal following tumour excision. Immunoreactive renin staining, using a polyclonal antibody to human renin, was performed in the 12 patients. Staining was positive in ten patients. The most intense staining was noted in the areas of cortex entrapped within the tumour, and in perivascular spaces not associated with entrapped cortex. These findings suggest that hypertension secondary to increased tumour associated renin production is a feature of congenital mesoblastic nephroma.