Soft tissue
Adipose tissue

Author: Vijay Shankar, M.D.

Revised: 28 January 2018, last major update August 2012

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Hibernoma [title]

Cite this page: Shankar, V. Hibernoma. website. Accessed August 20th, 2018.
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



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

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

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)
Electron microscopy images

Images hosted on other servers:

Pleomorphic mitochondria with dense matrices

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