title: Papillary renal cell-like carcinoma in a retroperitoneal teratoma.
abstract: We report a case of somatic type malignancy with papillary renal cell carcinoma differentiation arising in a retroperitoneal mixed germ cell tumor. The patient was a 36-year-old man with a synchronous mediastinal teratoma. The somatic type malignancy in the retroperitoneal tumor was composed of papillary structures covered by atypical epithelial cells with eosinophilic cytoplasm, prominent nucleoli and pseudostratified nuclei. Papillary cores contained numerous aggregates of foamy macrophages, typical of type I papillary renal cell carcinomas. The immunohistochemical profile was consistent with papillary renal cell carcinoma, including positive reactions for cytokeratin 7 and alpha-methyl acyl CoA racemase. There was no somatic type malignancy component in the synchronous mediastinal teratoma. Both the retroperitoneal and the mediastinal tumor showed gains of 12p and chromosome 17 material. There was no c-MET mutation in the somatic type malignancy. To our knowledge, this is the first report of a somatic type malignancy with features of papillary renal cell carcinoma arising in a germ cell tumor. It is important not to confuse such a retroperitoneal tumor with a conventional papillary renal cell carcinoma, because presence of other malignant histologies within the germ cell tumor may warrant different treatment. In such cases, the presence of isochromosome 12p can be helpful to the diagnosis.
authors.affiliation: Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia. zmarusic@kbsm.hr
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Marusić
authors.forename: Mario
authors.initials: M
authors.lastname: Zovak
authors.forename: Jill M
authors.initials: JM
authors.lastname: Hagenkord
authors.forename: Shera
authors.initials: S
authors.lastname: Kash
authors.forename: Manika Sapru
authors.initials: MS
authors.lastname: Koul
authors.forename: Warren
authors.initials: W
authors.lastname: Sanger
authors.forename: Zoran
authors.initials: Z
authors.lastname: Gatalica
authors.forename: Bozo
authors.initials: B
authors.lastname: Kruslin
authors.forename: Davor
authors.initials: D
authors.lastname: Tomas
mesh_terms: D000328:Adult; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008479:Mediastinal Neoplasms / Q000473:pathology* / Q000601:surgery; D009378:Neoplasms, Multiple Primary / Q000473:pathology* / Q000601:surgery; D012186:Retroperitoneal Neoplasms / Q000473:pathology* / Q000601:surgery; D013724:Teratoma / Q000473:pathology* / Q000601:surgery