Using imaging to diagnose renal tumors beyond nephroblastoma

Wilm's tumor (WT) accounted for the vast majority of renal tumors in children (92%). However, there are many atypical or rare forms of kidney cancer, and it is certainly useful to have a diagnostic orientation in imaging to differentiate between the different diagnoses, guiding that way the therapeutic management. We report the cases of 3 patients who were initially diagnosed with nephroblastoma on the basis of radiological data (via PACS search), underwent pre-operative chemotherapy and then nephrectomy, and whose anatomopathological evidence came back in favor of benign renal tumors. Nephroblastoma is the most common renal tumor in children, but other benign tumors should not be neglected, radiological signs that may point to this entity should be taken into account, so that neoadjuvant chemotherapy with its enfeebling side effects can be avoided.

Case report of an infant with congenital mesoblastic nephroma leading to pulmonary metastasis

Congenital mesoblastic nephroma is considered a tumour with favourable clinical behaviour with only few reported cases of metastases. We report an infant who underwent complete resection and later developed pulmonary metastasis. Ten-month-old baby girl initially presented at 3 weeks of age with macroscopic haematuria, hypertension and a lumbar mass. Contrast-enhanced computed tomography revealed a tumour arising from the left kidney without local invasion or metastasis. She underwent left nephrectomy. Immunohistochemistry confirmed a cellular type of congenital mesoblastic nephroma. At 10 months, she presented with difficulty in breathing. Contrast-enhanced computed tomography revealed an opacity in the right hemi-thorax. Histology of lung mass was suggestive of deposits from the previously excised mesoblastic nephroma. She developed a right-sided haemothorax and succumbed. This case report highlights the fact that even though congenital mesoblastic nephromas are considered tumours with favourable clinical behaviour, they can present later with distant metastasis. Therefore, clinicians need to be aware of this rare malignant potential and adhere to meticulous follow-up protocols.

Cellular congenital mesoblastic nephroma detected by prenatal MRI: a case report and literature review

Congenital mesoblastic nephroma (CMN) is a rare tumor, yet it is the most frequently diagnosed renal neoplasm in the first 3 months of life. CMN reports with prenatal magnetic resonance imaging (MRI) are scarce. Our aims were to describe a case with fetal MR imaging along with other findings, and to review the literature concerned with prenatal MRI detection of CMN. Upon routine ultrasound (US) examination of a 36-week pregnant woman, a fetal abdominal mass was disclosed. Prenatal MRI revealed a large, well-circumscribed renal mass of solid and cystic components, not invading the adjacent tissues, but compressing normal renal parenchyma of the lower pole of the left kidney. Thus, a low malignant renal tumor was considered. After Cesarean delivery, imaging including US and computerized tomography (CT) scan was performed on the apparently healthy boy and verified the prenatal MRI finding. Accordingly, left nephrectomy was performed at the age of 12 days. The pathology confirmed CT results of the solid and cystic components of the mass, in addition to the necrotic and hemorrhagic constitution. Cellular CMN was diagnosed, and ETV6 gene rearrangement was demonstrated by FISH analysis. No recurrence was detected within the 40 months follow-up after the operation. Our report described a rare and seldomly detected renal tumor in utero with the aid of MRI and reviewed the few related reports in the literature in which MRI was performed prenatally. This report also highlights the need for prenatal MRI as a complementary tool to US in cases with suspected fetal renal mass and recommends its use for carefully managing the possible risks during the perinatal period.

Imaging of fetal tumors and other dysplastic lesions: A review with emphasis on MR imaging

Fetal tumors and other dysplastic masses are relatively rare. They are usually the result of failure of differentiation and maturation during embryonic or fetal life; dysplastic lesions may be the consequence of an obstruction sequence. In this review, we present the most commonly encountered tumors and masses seen during fetal life. Imaging characteristics, tumoral organ of origin, and its effect on the surrounding organs and overall fetal hemodynamics are descriptors that must be relayed to the fetal surgeon and maternal fetal medicine expert, in order to institute most accurate parental counseling and appropriate perinatal treatment plan.

Imaging manifestations of congenital mesoblastic nephroma

OBJECTIVE

Congenital mesoblastic nephroma (CMN) is a rare renal tumor mainly observed in infants and young children. This study aims to analyze the imaging manifestations of CMN to improve the understanding of the disease.

METHODS

The imaging manifestations and clinical records of all pediatric patients with CMN admitted to our hospital over the last 7 years were retrospectively analyzed. The diagnosis of CMN was confirmed by postoperative pathology. All patients underwent computed tomography (CT) scans; 2 patients additionally underwent magnetic resonance imaging (MRI) scans (including one prenatal MRI scan).

RESULTS

We evaluated 10 pediatric patients (6 males and 4 females) aged 7 days to 12 months (median age: 4 months) with CMN located on the left kidney in six cases and the right kidney in four cases. The CT imaging manifested as solid lesions (5 cases), solid-cystic lesions with solid predominance (4 cases), or solid-multicystic lesions with cystic predominance (1 case). Enhanced CT showed moderately and heterogeneously enhanced solid component and intracystic septations at the corticomedullary phase that were further enhanced at the nephrographic phase, although their CT values were still lower than those of the renal parenchyma. The "double-layer sign" were seen in 4 cases of classic type of CMN, and the "intratumor pelvis sign" were seen in 9 cases that include 5 classic, 3 cellular and 1 mixed type of CMN. In the 2 patients who underwent MRI, the scans showed solitary masses. The lesions had hypointense signals on the T1WI sequence and isointensity or slightly lower-intensity signals than the surrounding renal parenchyma on the fluid-sensitive sequences, whereas the lesions showed hyperintense signals on the diffusion-weighted imaging (DWI) sequence.

CONCLUSIONS

The imaging manifestations of CMN are closely correlated with the pathological subtype and have certain characteristics. The "double-layer sign" was seen with most classic type CMN, and "intratumor pelvis sign" was seen in 90% cases.

Congenital Mesoblastic Nephroma Presenting With Refractory Hypertension in a Premature Neonate: A Case Study

The most common nonencapsulated solid renal tumor in the neonatal period is congenital mesoblastic nephroma. Mesoblastic nephroma is a solid lesion originating within or extending from the renal parenchyma. These tumors proliferate rapidly, typically within 3-6 months after birth. Mesoblastic nephromas are stratified by classification as either classical (benign) or atypical (malignant); masses composed of both benign and malignant cells are also reported. The hallmark clinical manifestation of mesoblastic nephroma is a palpable abdominal mass, which may be accompanied by hypertension, hypercalcemia, hematuria, and polyuria. Differentiating between benign and malignant renal tumors is essential to invoke a timely, evidence-based management and treatment plan. With appropriate surgical intervention in a timely manner, prognosis is excellent and mesoblastic nephroma is considered curable. We present a case involving a premature infant with congenital mesoblastic nephroma with discussion of embryology, pathophysiology, diagnostic, management, and prognostic implications for the neonate and family.