Prenatal diagnosis and postnatal management of congenital mesoblastic nephroma: Experience at a single center in China

Objective To review the prenatal and postnatal clinical characteristics and pathological subtypes, as well as the surgical outcome for congenital mesoblastic nephroma (CMN) cases. Method A retrospective review was performed in 11 cases with CMN prenatally diagnosed at a single center between 2015 and 2019. The clinical characteristics, surgical outcome, histopathology, and follow‐up were retrospectively obtained and reviewed. Results The median gestational age at which the sonographic diagnosis was made was 35 weeks. Polyhydramnios was found in four (36.4%) cases, and all resulted in a preterm birth. Nine infants had hypertension. Ten cases underwent radical nephrectomy, and one underwent radical nephrectomy and partial adrenalectomy. The pathological results showed that six tumors were classical variants, four mixed variants, and one was a cellular variant. Three cases presented as a stage I, eight as stage II, and no stage III or IV cases were diagnosed. All patients are alive so far. At a median follow‐up of 14 months, no local recurrence, or remote metastases were found. Conclusion The prognosis of prenatal CMN cases is excellent after early surgery. Key Points What is already known on this topic? Congenital mesoblastic nephroma (CMN) is a rare renal tumor that can be diagnosed in late pregnancy. Although CMN is a benign tumor and the majority of patients are cured by surgical resection, local recurrence, and remote metastases have been reported. What this study adds? The majority cases of fetal CMN have a classical or mixed type on histology. The prognosis of fetal CMN is excellent after early surgery. CMN developed in fetal stage seems to be a more favorable subtype.