Soft tissue

Adipose tissue tumors

Other benign lesions


Last author update: 1 August 2012
Last staff update: 21 March 2022

Copyright: 2002-2022,, Inc.

PubMed Search: Hibernoma [title]

Vijay Shankar, M.D.
Page views in 2021: 9,902
Page views in 2022 to date: 6,851
Cite this page: Shankar V. Hibernoma. website. Accessed August 14th, 2022.
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
Radiology images

Contributed by Mark R. Wick, M.D.

MRI, tricep muscle

Case reports
  • Excision
  • May recur if incompletely excised
Clinical images

Contributed by Mark R. Wick, M.D.

Gluteal cleft

Images hosted on other servers:

Supraclavicular tumor

Gross images

Contributed by Mark R. Wick, M.D.

Images hosted on other servers:

Thigh tumor

Neck tumor



Microscopic (histologic) 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+)
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Various images

AFIP images

Lobulated pattern

Granular to multivacuolated cytoplasm

Mixed with white fat

Images hosted on other servers:

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)
Molecular / cytogenetics description
  • 11q13-21 rearrangements (also seen in lipomas and liposarcomas)
Differential diagnosis
Additional references
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