Abstract

Background: multiple primary malignant neoplasms are not frequent but are increasing in incidence; some of them are associated with genetic syndromes like Von Hippel-Lindau and Li-Fraumeni. Dedifferentiated liposarcoma is one of the rarest soft tissue tumors and clear cell renal carcinoma is the most frequent kidney cancer. The concomitant presence of these tumors is extremely rare, however, there have been some cases reported, none of them presenting with a liposarcoma of the limbs. This report looks to expose an interesting case of a synchronous multiple primary tumors patient presenting with a very rare liposarcoma associated with a renal cell carcinoma (a very rare association). A review of the literature and a collection of similar cases published previously are also provided. Case presentation: here we expose the case of a 62-year-old, Hispanic man who presents with a left thigh mass compatible with dedifferentiated liposarcoma which was synchronous with a metastatic clear cell renal carcinoma. Multiple treatment lines were provided with no response, with a further metastatic transformation. Genetic analysis by liquid biopsy showed some mutations that were not susceptible of targeted therapy. At the time of this report the patient is undergoing palliative care as he persists with a non-responsive metastatic disease. Conclusions: we present the first case reported of a clear cell renal carcinoma synchronous to a dedifferentiated liposarcoma of a limb. The association between renal cell carcinoma and dedifferentiated liposarcoma is unusual and there are few reports in the literature. More research about these tumors along with genetic tests need to be performed looking for a better understanding of the fundamental basis of this rare association.