Soft tissue
Adipose tissue
Round cell liposarcoma

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 9 August 2016, last major update August 2012

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

PubMed Search: Round cell liposarcoma

Cite this page: Round cell liposarcoma. website. Accessed July 21st, 2018.
Definition / general
  • High grade tumor composed of small round or spindled cells with frequent mitotic figures
  • Also called poorly differentiated myxoid liposarcoma
Case reports
Clinical images

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Round cell liposarcoma

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Solitary skin-colored subcutaneous mass

Gross description
  • Opaque white nodules, fleshy
Gross images

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Thigh tumor post-chemotherapy

Microscopic (histologic) description
  • Cellular areas of small, round or spindled cells with sparse eosinophilic and granular cytoplasm and large nuclei; may resemble lymphoma or other round cell tumors
  • Scattered lipoblasts, frequent mitotic figures and necrosis
  • Frequent pseudoglandular tumor cells
  • Vasculature is less prominent than pure myxoid cases
  • Often a transition between well differentiated myxoid and poorly differentiated round cell areas
  • Note: classify as round cell if 5% or more of tumor volume
Microscopic (histologic) images

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Sheets of primitive round cells

Small round cells are pleomorphic


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Round cell liposarcoma

Comparison of
well differentiated and
poorly differentiated
(round cell) tumors

Small round
tumor cells with
minimal cytoplasm
in myxoid stroma

Perivascular pattern

Invasion of fascia

Pseudocystic cavity due to necrosis

Branched capillaries in myxoid poor stroma

Alcian blue PAS stain

Cytology description
  • Hypercellular smears with single round cells with scant cytoplasm and naked nuclei
  • Nuclei usually round, occasionally oval
  • Variable background vacuoles, intracytoplasmic vacuoles, fragments of myxoid stroma with neoplastic cells
  • No prominent pleomorphism (Cancer 2003;99:28)
Cytology images

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Various images

Positive stains
  • CD31 and CD34 highlight vasculature
  • S100+ lipoblasts (30 - 50%)
Electron microscopy description
Molecular / cytogenetics description
Differential diagnosis
  • Ewing / PNET: neuroendocrine morphology, CD99+, translocations involving EWS gene
  • Lymphoma: positive for B (CD20, CD79a) or T cell (CD3, CD4) markers
  • Melanoma: various histologic patterns, usually prominent nucleoli, S100+ tumor cells, HMB45+
  • Metastatic carcinoma: clinical history, keratin+ cells, may have more pleomorphism