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Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 16 March 2013, last major update March 2013
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.


Murine Double-Minute 2
● Protein that inhibits p53; gene is at 12q13-15

Clinical features

● Amplified in well-differentiated liposarcoma and dedifferentiated liposarcoma (amplification detected by comparative genomic hybridization, qualitative PCR, FISH; MDM2 immunostain correlates with gene amplification
● MDM2 T309G polymorphism might be a risk factor for leukemia among Asians but not Caucasians (Leuk Lymphoma 2012;53:2245)

Uses by pathologists

● Distinguish well-differentiated liposarcoma (positive, FISH is 90% sensitive, Mod Pathol 2012;25:1384) from benign adipose tumors (negative); FISH is more sensitive than immunostains on needle biopsies (Mod Pathol 2010;23:1301)
● Distinguish dedifferentiated liposarcoma (positive) from poorly differentiated sarcomas (negative)
● Distinguish low-grade osteosarcoma (positive) from benign fibrous and fibro-osseous lesions (negative, Mod Pathol 2011;24:624)
● MDM2 and CDK4 coexpression in high grade osteosarcoma suggests progression from low grade osteosarcoma (Am J Surg Pathol 2012;36:423)
● CDK4 is more specific but less sensitive than MDM2 (Am J Surg Pathol 2005;29:1340)

Micro / molecular images

Lip: active cheilitis - intense nuclear immunostaining in all stratified epithelium cells

Liposarcoma, well differentiated (immunostains and FISH)

Liposarcoma, well differentiated, inflammatory subtype versus sclerosing mesenteritis (immunostains and FISH)

Lung cancers


Osteosarcoma, low grade (immunostains)

Positive staining - disease

● Liposarcoma: well-differentiated and dedifferentiated
● MPNST (20%, Arch Pathol Lab Med 2012;136:95)
● Osteosarcoma, low-grade and those that dedifferentiate to high grade osteosarcoma
● Rhabdomyosarcoma, sclerosing (some cases, Hum Pathol 2009;40:1347)

Negative staining

● Benign adipose tumors, poorly differentiated sarcomas
● Benign fibrous and fibro-osseous lesions
● Liposarcoma, pleomorphic of skin/subcutis (usually, Am J Surg Pathol 2012;36:1047)
● Neurofibroma, schwannoma
● Rhabdomyosarcoma, pediatric (Sarcoma 2012;2012:492086)

End of Stains > MDM2

Ref Updated: 16Mar13 (NLP)

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