Soft tissue
Adipose tissue

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

Revised: 8 August 2016, last major update August 2012

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

PubMed Search: Hibernoma [title]

Cite this page: Hibernoma. website. Accessed October 22nd, 2016.
Definition / General
  • Lipoma containing prominent brown adipocytes that resembles normal brown fat as classic lipoma resembles white fat
  • Rare (2% of lipomas)
  • Mean age 26 - 38 years; 60% male
  • Most commonly in axilla, back, mediastinum, shoulder, thigh (Am J Surg Pathol 2001;25:809); also abdominal cavity, arm, breast, paraglottic space, parasacral region, retroperitoneum, spermatic cord
Clinical Features
  • May produce steroid hormones
Case Reports
  • Excision
  • May recur if incompletely excised
Clinical Images

Images hosted on PathOut servers:

MRI, tricep muscle (left) and gluteal cleft (right), courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Supraclavicular tumor

Gross Images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Thigh tumor

Neck tumor



Micro Description
  • Organoid arrangement of uniform large cells resembling brown fat with coarsely granular to multivacuolated cytoplasm that is eosinophilic or pale
  • Vacuoles are small and stain for neutral fat
  • Nucleus is small, central with no / rare atypia
  • Often mixtures of white fat
  • May have loose basophilic matrix, features of spindle cell lipoma (if in neck / scalp), only scattered hibernoma cells
  • Subtypes: classic, lipoma-like, myxoid (Ann Diagn Pathol 2006;10:104), spindle cell (CD34+)
Micro Images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Lobulated pattern

Granular to multivacuolated cytoplasm

Mixed with white fat

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Granular to multivacuolated cytoplasm

Vascular changes





Multivacuolated tumor cells are S100+


Cytology Description
  • Small, round, brown fat-like cells with uniform, small cytoplasmic vacuoles and regular, small, round nuclei
  • Delicate branching capillaries
  • Variable mature fat cells (Cancer 2001;93:206)
Positive Stains
Negative Stains
  • CD34 (usually), p53 (usually, but see case report above)
Electron Microscopy Description
  • Resembles brown fat
  • Each tumor cell is invested by a basal lamina
  • Inverse relationship exists between lipid droplet size and the number of mitochondria per unit of cytoplasm
  • Pleomorphic mitochondria with dense matrices or large round mitochondria with transverse lamellar cristae
  • Undulating plasmalemmal invaginations, micropinocytotic vesicles, periodic short plasmalemmal densities
  • Conspicuous lack of cytoplasmic membrane systems (Hum Pathol 1983;14:677)
Electron Microscopy Images

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Pleomorphic mitochondria with dense matrices

Molecular / Cytogenetics Description
  • 11q13-21 rearrangements (also seen in lipomas and liposarcomas)
Differential Diagnosis
Additional References