Liposarcomatous differentiation in malignant phyllodes tumours is unassociated with MDM2 or CDK4 amplification

Pamela L. Lyle, Julia A. Bridge, Jean F. Simpson, Justin M. Cates, Melinda E. Sanders

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Aims: Breast sarcomas are rare, usually occurring in the setting of malignant phyllodes tumour (MPT). Heterologous differentiation commonly resembles well-differentiated or pleomorphic liposarcoma. In extramammary sites, these subtypes have different biological behaviours and distinct genetic alterations: MDM2 and CDK4 amplification in well-differentiated liposarcoma, and polyploidy with complex structural rearrangements in pleomorphic liposarcoma. The aim of this study was to investigate foci resembling well-differentiated liposarcoma in MPT for MDM2 and CDK4 amplification. Methods and results: We evaluated the clinicopathological characteristics of MPTs received by the Vanderbilt Breast Consultation Service containing components resembling well-differentiated or pleomorphic liposarcoma. Cases with available tissue blocks were subjected to fluorescence in-situ hybridization with MDM2 and CDK4 probes. Thirty-eight MPTs with liposarcomatous components were available for review. The mean patient age was 49.8 years (range 26-84 years). In addition to well-differentiated liposarcoma, the following components were also present: high-grade undifferentiated sarcoma (n = 9; 23.7%), pleomorphic liposarcoma (n = 4; 10.5%), non-high-grade sarcoma not otherwise specified (n = 22; 57.9%), and malignant peripheral nerve sheath tumour-like (n = 2; 5.2%). Among 10 cases tested, none showed amplification of MDM2 or CDK4. Conclusions: This study examined molecular changes in the well-differentiated liposarcomatous components of MPT. Despite histological similarity to well-differentiated liposarcoma of soft tissues, liposarcomatous differentiation in MPT lacks the molecular phenotype characteristic of extramammary well-differentiated liposarcoma.

Original languageEnglish (US)
Pages (from-to)1040-1045
Number of pages6
Issue number7
StatePublished - Jun 1 2016


  • CDK4
  • Liposarcoma
  • Liposarcomatous differentiation
  • MDM2
  • Malignant phyllodes tumour

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology


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