title: Dedifferentiated chromophobe renal cell carcinoma with massive osteosarcoma-like divergent differentiation: a singular entity in the spectrum of retroperitoneal calcifying tumors.
abstract: Sarcomatoid change in renal cell carcinoma is the result of the dedifferentiation of the "parent" tumor into a high-grade malignancy characterized by sarcoma-like features and associated with an accelerated clinical course and poorer prognosis. Any of the renal cell carcinoma subtypes can undergo sarcomatoid dedifferentiation, with the chromophobe variant being the most prone. The present report describes the case of a woman affected by a classic chromophobe renal cell carcinoma that developed dedifferentiation accompanied by a very rare osteosarcoma-like divergent differentiation, which constituted about 90% of the entire retroperitoneal mass. In addition to presenting the relevant imaging, histopathological, and immunohistochemical findings, this article briefly discusses the main differential diagnosis of retroperitoneal ossifying/ calcifying masses, which could give rise to diagnostic problems either in small biopsies or at imaging.
authors.affiliation: Department of Clinical Sciences, University of Parma, Parma, Italy.
authors.forename: Federica A
authors.initials: FA
authors.lastname: Gira
authors.forename: Antonio
authors.initials: A
authors.lastname: Barbieri
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fellegara
authors.forename: Maurizio
authors.initials: M
authors.lastname: Zompatori
authors.forename: Domenico
authors.initials: D
authors.lastname: Corradi
mesh_terms: D000368:Aged; D002114:Calcinosis / Q000150:complications / Q000473:pathology; D002292:Carcinoma, Renal Cell / Q000150:complications / Q000556:secondary* / Q000601:surgery; D054337:Cell Dedifferentiation; D002471:Cell Transformation, Neoplastic; D003937:Diagnosis, Differential; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000150:complications / Q000473:pathology* / Q000601:surgery; D009378:Neoplasms, Multiple Primary; D012516:Osteosarcoma / Q000473:pathology*; D011877:Radionuclide Imaging; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis; D014057:Tomography, X-Ray Computed