MDM2 and atypical lipomatous tumor: In addition to LPSs, other sarcomas can show positivity for the MDM2 immunostain and/or amplification of the MDM2 gene, including atypical lipomatous tumors,[7] malignant peripheral nerve sheath tumors,[7, 20] myxofibrosarcomas,[7] rhabdomyosarcomas,[7, 21] and others.[7, 22] In addition, other tumors aside from sarcomas can show MDM2 amplification, including melanoma.[23] Thus, MDM2 may be more helpful in deciding if a lesion is malignant, and may not be as helpful in specifically subtyping a neoplasm as a LPS.