PDGFRa amplification in multiple skin lesions of undifferentiated pleomorphic sarcoma (UPS): a clue for intimal sarcoma metastases

Abstract

A 62-year-old HIV-positive man was admitted for multiple cutaneous and subcutaneous nodules on his lower limbs, corresponding to an undifferentiated proliferation of spindle and pleomorphic cells, with irregular nuclei and numerous mitoses. The tumor cells were negative for a large panel of immunohistochemical markers, except CD10. MDM2 immunohistochemical staining was also negative, leading to the diagnosis of FNCLCC grade III Undifferentiated Pleomorphic Sarcoma (UPS). aCGH showed a highly complex karyotype, with amplification of the 4q12 region, an area that contains only the PDGFRa gene. This amplification of PDFGRa, molecular hallmark of Intimal Sarcoma (IS), led to the diagnosis of skin IS metastasis. A positron emission tomography (PET) showed a hypermetabolic mass protruding in the pre-aortic area, consistent with the diagnosis of aortic IS. Our study shows that a rare differential diagnosis in peripheral UPS can be IS skin metastasis, and underlines the importance of molecular analyses in UPS.

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