Soft tissue
Adipose tissue
Inflammatory liposarcoma - subtype of atypical lipomatous tumor / well differentiated liposarcoma

Author: Charanjeet Singh, M.D. (see Authors page)

Revised: 10 August 2016, last major update June 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Inflammatory liposarcoma

Definition / General
  • Nodular aggregates of chronic inflammatory cells with scattered large atypical cells
  • Paucicellular stroma with fibroblastic cells
  • Remaining lesion is typical well differentiated liposarcoma (Am J Surg Pathol 1997;21:518)
  • Not a WHO diagnosis
Epidemiology
Case Reports
Gross Images

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35 cm tumor weighing 9 kg

Retroperitoneal tumor

Micro Description
  • Prominent chronic inflammation that resembles lymphoma and may obscure sarcomatous component
  • Lymphocytes distributed in three distinct patterns:
    • (1) Scattered throughout the tumor, both in fibrous septae and in adipocytic areas
    • (2) In clusters
    • (3) As immature follicles
  • Clusters and follicles are usually perivascular; vessels are surrounded by lymphocytes, but with no evidence of vasculitis (Am J Surg Pathol 2012;36:941)
Micro Images

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Inflammatory variant



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Focal dense inflammatory infiltrate

Various images

Cytology Description
  • Numerous dispersed lymphocytes and plasma cells
  • Scattered large atypical cells with abundant ill defined cytoplasm, multiple or hyperlobated nuclei and coarse chromatin
  • Also fibrous tissue fragments containing both types of cells (Diagn Cytopathol 1999;20:229)
Differential Diagnosis
  • Hodgkin’s lymphoma: no well differentiated liposarcoma component, no lipoblasts, negative for MDM2, CDK4, 12q13-15 rearrangement
  • Inflammatory pseudotumor: no well differentiated liposarcoma component, no lipoblasts, negative for MDM2, CDK4, 12q13-15 rearrangement (Am J Surg Pathol 1997;21:884)
  • MFH-inflammatory: no well differentiated liposarcoma component, no lipoblasts, negative for MDM2, CDK4, 12q13-15 rearrangement
  • Sclerosing mesenteritis or idiopathic retroperitoneal fibrosis: no well differentiated liposarcoma component, no lipoblasts, negative for MDM2, CDK4, 12q13-15 rearrangement (Mod Pathol 2009;22:66)