Soft tissue
Adipose tissue tumors
Lipoma and variants
Spindle cell / pleomorphic lipoma


Topic Completed: 1 August 2012

Minor changes: 10 September 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Pleomorphic lipoma / spindle cell lipoma

Vijay Shankar, M.D.
Cansu Karakas, M.D.
Page views in 2019: 3,705
Page views in 2020 to date: 7,625
Cite this page: Shankar V. Spindle cell / pleomorphic lipoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissueadiposepleomorphicgeneral.html. Accessed September 23rd, 2020.
Definition / general
  • Subcutaneous tumor of back, shoulder or posterior neck with mature adipocytes, bland spindle cells, floret cells and collagen (Stanford University)
  • In breast, a rare variant of lipoma characterized by a mixture of mature adipocytes, collagen forming spindle cells and varying degrees of myxoid change, first reported by Toker et al. in 1981 (Cancer 1981;48:1615)
Terminology
Epidemiology
  • Pleomorphic lipoma and spindle cell lipoma represent a continuum of benign tumors - most tumors show some features of both (J Cancer Res Clin Oncol 1994;120:707)
  • 70% occur in subcutaneous tissue of shoulder, back and posterior neck
  • 90% men
  • Usually ages 45 - 65 years
  • Usually relatively superficial
  • If deep, some suggest calling well differentiated liposarcoma
Epidemiology
Case reports
Treatment
  • Excision
  • Only rare local recurrences, no metastases
Gross description
  • Usually 3 - 5 cm, well circumscribed, yellow-gray-white, firmer than classic lipoma
Gross images

AFIP images

Yellow tumor due to numerous adipocytes

Microscopic (histologic) description
  • Circumscribed tumor with adipocytes that are variable in size at low power
  • Spindle cell lipoma typically contains three components: thin, uniform spindle cells arranged in short, parallel bundles, mature adipocytes and ropy birefringent collagen
  • Myxoid background appears as a thin, amorphous and semitransparent substance
  • Pleomorphic tumors have prominent floret giant cells (hyperchromatic, multinucleated, wreath-like nuclei) and small round hyperchromatic cells
  • No / rare lipoblasts, no prominent vascularity, rare mitotic figures, no necrosis
Microscopic (histologic) images

AFIP images

Numerous pleomorphic and floret cells


Adipocytes, spindle cells and ropy collagen


Pseudoangiomatous
appearance

Spindle cells have
inconspicuous cytoplasm
and small, slender,
uniform nuclei

Spindle cells and collagen with few adipocytes

Cytology description
Positive stains
Negative stains
Electron microscopy description
Molecular / cytogenetics description
  • Structural rearrangements of 13q (Rb) or losses of an entire chromosome 13 are the most common cytogenetic aberrations but 16q deletions and other variations are also possible (Cancer Genomics Proteomics 2018;15:193)
Differential diagnosis
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