Cellular Mesoblastic Nephroma with Liver Metastasis in a Neonate: Prenatal and Postnatal Diffusion-Weighted MR Imaging

Congenital mesoblastic nephroma (CMN) is the most common renal tumor in the first year of life. Here, we present unique findings of cellular variant CMN seen on prenatal and postnatal MRI with diffusion-weighted imaging (DWI).The mass was well-visualized on prenatal MR DWI with diffusion restriction in the solid portions. After excision of the mass, follow-up whole body MRI with DWI helped identify local tumor recurrence with suspicious liver metastasis. This hepatic lesion also showed diffusion restriction.

Nefroma mesoblástico congênito subtipo celular: relato de caso / Cellular congenital mesoblastic nephroma: case report

INTRODUÇÃO: Nefroma Mesoblástico Con-gênito é uma rara neoplasia renal pediátrica. Apresenta dois subtipos histológicos, clássico e celular, sendo o último de pior prognóstico e responsável por aproximadamente dois terços dos casos. Esse tumor ainda é um desafio diagnóstico aos patologistas devido à similaridade com outras neoplasias pediátricas renais mais frequentes. RELATO DO CASO: Criança do gênero feminino, 2 anos e 9 meses de idade, foi encaminhada a serviço médico com referência em oncologia apresentando massa renal à esquerda. Após nefrectomia, o estudo do espécime mostrou, macroscopicamente, extensa área tumoral granular, brancoacinzentada, ocupando aproximadamente todo o rim, invadindo seio renal, cápsula e gordura perirrenal, com áreas de hemorragia e necrose. Histologicamente, caracterizava-se pela presença de células fusiformes e mitoses, sem atipias celulares. O diagnóstico foi de Nefroma Mesoblástico Congênito subtipo celular e a paciente foi submetida a quimioterapia. Durante o primeiro ano de tratamento, houve recidiva do tumor, apresentando-se irressecável e sem resposta a nova quimioterapia. A paciente foi a óbito aos 4 anos de idade. DISCUSSÃO: O subtipo celular do nefroma mesoblástico tende a ser mais agressivo, apresentando uma taxa de sobrevivência de 85 por cento, comparada com 100 por cento para a variante clássica. Geralmente, a recorrência ocorre no primeiro ano de tratamento, principalmente quando o subtipo é o celular.

INTRODUCTION: Congenital Mesoblastic Nephroma (CMN) is a rare pediatric renal tumor. It comprises two histological subtypes, namely classic and cellular, with the second accounting for two thirds of all cases and being more often associated with poor prognosis. It remains a diagnostic challenge for pathologists due to its similarity with other more frequent pediatric kidney neoplasms. CASE REPORT: We describe the case of a 2-year- old girl who presented with a left renal mass. After nephrectomy, the specimen analysis showed, on gross examination, an extensive, granular and whitish tumor lesion occupying almost the entire kidney, invading the renal sinus, capsule and perirenal fat, with areas of hemorrhage and necrosis. Histologically, it was characterized by ovoid spindle cells, mitoses and no cell atypia, which led to a diagnosis of cellular mesoblastic nephroma. Adjuvant chemotherapy was carried out, but tumor recurrence occurred in the first year, presenting as an unresectable tumor that did not respond to adjuvant chemotherapy and the patient died at 4 years of age. DISCUSSION: The cellular variant tends to be more aggressive, with a survival rate of 85 percent versus 100 percent for the classic variant. Recurrence generally occurs in the first year, particularly with the cellular variant.

Unusual Mesoblastic nephroma: a report of two cases

Congenital mesoblastic nephroma [CMN] is a very rare tumour of early infancy with 80% of the cases being diagnosed within the first month of life. Complete surgical excision is almost always curative. We report two unusual large renal tumours in a 22-month-old boy and a 4-year-old girl who were diagnosed preoperatively as rhabdoid tumour and Wilms' tumour respectively. One of them was subjected unnecessarily to preoperative chemotherapy. Histological evaluation after complete radical excision demonstrated CMN

Nefroma mesoblástico congénito. Variante multiquística / Congenital mesoblastic nephroma. Multicystic variant

Se presenta un caso de Nefroma Mesoblástico Congénito (NMC) en un paciente de un año y cinco meses de edad que ingresa por un cuadro diarreico agudo, constatándose en el exámen médico una tumoración abdominal. La ecografía y la tomografía computada de aparato urinario evidenciaron proceso expansivo renal multiquístico derecho. Se realizó nefrectomía diagnosticándose, por el estudio anatomopatológico, nefroma mesoblástico congénito, variante celular a forma multiquística. La evolución fue favorable no presentando evidencias de recidiva local ni metástasis luego de dos años y cuatro meses de seguimiento. Se destaca la importancia del exámen físico exhaustivo durante los controles pediátricos periódicos, lo que permite un diagnóstico temprano de las masas abdominales.

Atypical mesoblastic nephroma. A potentially malignant variant of congenital mesoblastic nephroma. Review of literature & report of four cases.

Atypical Mesoblastic Nephroma (AMN) is a rare infantile renal tumour which may behave aggressively, in contrast to conventional Mesoblastic nephroma. During a 10 year period we encountered four cases of AMN. The mean age of presentation was three months. Size varied from 9-18 cms. All were soft and fleshy with a weight varying from 290-1200 gms. Three cases revealed cystic changes. Hemorrhage and necrosis was seen in all four cases. One case had associated Nephroblastomatosis Complex. The capsule and ureter were involved in one case each. Two of the four patients died of distant metastasis. Thus a close periodic follow up by non-invasive imaging techniques is indicated for early detection of recurrence and or metastasis in cases of AMN.