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Int J Clin Exp Pathol 2010;3(5):534-540

Case Report
Chromophobe renal cell carcinoma with liposarcomatous dedifferentiation
-report of a unique case

Fredrik Petersson, Michal Michal, Marcello Franco, Ondrej Hes

Department of Pathology, National University Hospital System, Singapore; Sikl's Department of Pathology, Charles University, Medical Faculty
Hospital, Pilsen, Czech Republic; Departmentt of Pathology, Federal University of Sao Paolo EPM/UNIFESP, Brazil

Received January 25, 2010, accepted April 23, 2010, available online May 5, 2010

Abstract: Sarcomatoid transformation of chromophobe renal cell carcinoma (CRCC) is a well recognized phenomenon. Of the published
cases with sarcomatous transformation of CRCC, none have shown liposarcomatous dedifferentiation. Out of a cohort of 250 cases of CRCC,
19 (7.6%) showed sarcomatous differentiation. In one case (female, age 46 years), the sarcomatous component of the tumor displayed
histological features of a pleomorphic liposarcoma. Light microscopic examination revealed a biphasic pattern with a chromophobe renal cell
carcinoma(CRCC) and a high-grade sarcomatous component containing large pleomorphic lipoblasts. In several areas both components
were intermingled. The conventional CRCC component showed classic histological features with calcifications, medium-sized polygonal cells
arranged in solid-alveolar structures with raisinoid nuclei, pale-eosinophilic flocculent cytoplasm with perinuclear haloes. In addition, a
microcystic-adenomatous component had luminal spaces  filled with erythrocytes. The CRCC was positive with Hale´s colloidal iron-stain
whereas the sarcomatous component was negative. The CRCC component was diffusely positive for cytokeratin 7, parvalbumin and racemase
but negative for cytokeratin 20, vimentin, CD10, carboanhydrase IX and S100-protein. The pleomorphic liposarcomatous component displayed
immunereactivity for CD10, vimentin, racemase and focally for carboanhydrase IX. The proliferative activity (Mib-1/Ki-67) was 5% in the CRCC
and 30% in the pleomorphic liposarcomatous component. No immunereactivity for MDM2 or CDK4 was detected.This is the first reported case
of a sarcomatoid CRCC where the sarcomatous component of the tumor displayed features of a pleomorphic liposarcoma. The patient died
from widespread metastatic disease 12 months after nephrectomy.(IJCEP1001009).

Key words: Chromophobe renal cell carcinoma, liposarcoma, sarcomatous transformation, sarcomatoid

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Address all correspondence to:
Fredrik Petersson MD, PhD
Department of Pathology,
National University Health System,
5 Lower Kent Ridge Road, Singapore 119074.
Fax: +6567780671 Phone: +6597714890