Low-grade Osteosarcomatous Dedifferentiation of an Atypical Lipomatous Tumor in a Pediatric Patient

Benjamin J. Kukull, Mazdak Khalighi, Kenneth R. Gundle, Barry G. Hansford, Christopher L. Corless, Jessica L. Davis

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Atypical and malignant lipomatous tumors are infrequent in the pediatric population. Within this uncommon cohort, the morphologically and genetically related spectrum of atypical lipomatous tumor/well-differentiated liposarcoma/dedifferentiated liposarcoma (ALT/WDL/DDLS) is markedly rare. Their shared characteristic molecular aberration is a genomic amplicon of a region of chromosome 12q, including the oncogenes MDM2 and CDK4. We present an unusual case of a pediatric patient with an ALT, with recurrence after 2 years in the form of a bone-forming mass, radiologically and pathologically mimicking parosteal osteosarcoma, a tumor also molecularly characterized by amplification of MDM2 and CDK4. However, with ample histologic sampling, a single focus of lipogenic differentiation was identified, thus representing the first near complete low-grade osteosarcomatous dedififferentation reported within ALT/WDL/DDLS and the first ever in pediatric patient. The case serves a reminder of a diagnosis differential and pitfalls within MDM2-amplified tumors.

Original languageEnglish (US)
Pages (from-to)240-246
Number of pages7
JournalPediatric and Developmental Pathology
Issue number3
StatePublished - Jun 1 2020


  • MDM2
  • atypical lipomatous tumor
  • liposarcoma
  • osteosarcoma

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Pathology and Forensic Medicine


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