[P-27] Congenital mesoblastic nephroma classical type: a case report

Ichfa Namira and Bethy Suryawathy

Anatomical Pathology Department, Faculty of Medicine, Padjadjaran University / Dr Hasan Sadikin General Hospital, Bandung, Indonesia

Background: Congenital mesoblastic nephroma (CMN) is a rare, accounting for 3 – 10% of paediatric renal tumours. It is the most common renal tumour of newborns and usually discovered before 6 months of age. The diagnosis in children over the age of 2 is a rare case. CMN is divided into classical, cellular and mixed type that associated with an excellent prognosis. We present a rare case of CMN in a 2-month-old boy.

Case Presentation: A 2-month-old male baby presented with fever for the past 7 days. On physical examination, there was a palpable mass in abdomen. Glomerular filtration rate showed dysfunctional of right kidney. Ultrasonography showed medullary cystic kidney disease in right kidney. On gross examination, the kidney size was 5.5 x 3 x 2 cm. Microscopic examination revealed the tumour composed of interlacing fascicles of fibroblastic cells with thin nuclei and no mitotic activity. After nephrectomy, the patient was stable.

Discussion and Conclusion: Classic CMN is morphologically identical with infantile fibromatosis of the renal sinus. The differential diagnosis of CMN includes Wilm's tumor, adrenal neuroblastoma and clear cell sarcoma of the kidney. Microscopic examination showed tumour cells dissecting the island of renal parenchyma composed of interlacing fascicles of fibroblastic cells with thin nuclei. There were small island of hyaline cartilage and foci of extramedullary hematopoiesis. The patient was diagnosed with classical CMN because there were no pushing border or infantile fibrosarcoma-like pattern like in congenital mesoblastic nephroma cellular type. The final diagnosis was classical CMN.