Adipocytic tumours

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Adipocytic tumours fall into the grouping soft tissue lesions and includes things that are very common (e.g. lipoma) and everything from benign to malignant.

Lipoma

General

Microscopic

Features:

  • Collection of mature adipocytes.
    • Variation of size may be seen -- should prompt a search for lipoblasts.[1]

Notes:

  • Microscopically not definitely distinguishable from mature clump of fat.
    • The lesion must be labeled lipoma to be signed-out as such.

Pleomorphic lipoma

General

  • ???

Microscopic

Features:

  • Multinucleated cells - "floret cells".
    • Very ugly looking cells.
  • Fibrous septa.

Image: Floret cells in a pleomorphic lipooma (pathconsultddx.com).[2]

Notes:

  • May overlap with spindle cell lipoma.[3]

Hibernoma

General

  • Consists of brown fat (present in the infants to generate heat).[4]
  • Benign.
  • Usually asymptomatic.[5]

Epidemiology

  • Young adults.

Gross

  • Well-circumscribed.
  • Lobulated and light-brown on sectioning.

Microscopic

Features:[6]

  • Large polygonal/oval cells:
    • Nucleus - central & small.[7]
      • Nucleoli typically prominent.[8]
    • Cytoplasm - multivacuolated, oval, eosinophilic, granular.

Image:

Liposarcoma

  • Most common malignant sarcoma in the retroperitoneum.

Microscopy

Features:

  • Lipoblasts:
    • Large sharply demarcated vacuole.
    • Nucleus:
      • Hyperchromatic (dark staining) nucleus.
      • Eccentric location.
      • Nuclear indentation.

Images:

IHC

  • IHC is of limited value.
  • S-100 +ve ~1/3 of the time.
  • Reticulin ???.

See also

References

  1. PMID 8548119.
  2. URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970321-7. Accessed on: 4 December 2010.
  3. URL: http://surgpathcriteria.stanford.edu/softfat/spindle_cell_lipoma/. Accessed on: 4 December 2010.
  4. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 605. ISBN 978-0781765275.
  5. Ahmed SA, Schuller I (December 2008). "Pediatric hibernoma: a case review". J. Pediatr. Hematol. Oncol. 30 (12): 900–1. doi:10.1097/MPH.0b013e318184e6dd. PMID 19131775.
  6. Chen DY, Wang CM, Chan HL (March 1998). "Hibernoma. Case report and literature review". Dermatol Surg 24 (3): 393–5. PMID 9537018.
  7. http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6
  8. http://surgpathcriteria.stanford.edu/softfat/hibernoma/