title: Cellular congenital mesoblastic nephroma: case report.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  The cellular variant tends to be more aggressive, with a survival rate of 85% versus 100% for the classic variant. Recurrence generally occurs in the first year, particularly with the cellular variant.
authors.affiliation: Centro de Ciências da Saúde, Department of Pathology, Universidade Federal do Piauí, Brazil. linagsantos@uol.com.br
authors.forename: Lina Gomes dos
authors.initials: LG
authors.lastname: Santos
authors.forename: Juliana de Sousa Ribeiro de
authors.initials: Jde S
authors.lastname: Carvalho
authors.forename: Marcela Aguiar
authors.initials: MA
authors.lastname: Reis
authors.forename: Rayli Lauro Jennyfer Brandão
authors.initials: RL
authors.lastname: Sales
mesh_terms: D002675:Child, Preschool; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000151:congenital* / Q000175:diagnosis / Q000628:therapy; D018201:Nephroma, Mesoblastic / Q000151:congenital* / Q000175:diagnosis / Q000628:therapy