Adipocytic tumours
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.
Overview
This grouping includes a number of tumours, which can be divided based on their behaviour into benign, intermediate and malignant.
Benign
Benign adipocytic tumours:[1]
- Lipoma.
- Angiolipoma.
- Myolipoma.
- Pleomorphic lipoma.
- Lipomatosis.
- Lipomatosis of nerve.
- Lipoblastoma.
- Extrarenal angiomyolipoma.
- Extra-adrenal myelolipoma.
- Hibernoma.
Intermediate
Intermediate adipocytic tumours:[1]
- Atypical lipomatous tumour.
Malignant
Malignant adipocytic tumours:[1]
- Dedifferentiated liposarcoma.
- Myxoid liposarcoma.
- Pleomorphic liposarcoma.
- Mixed-type liposarcoma.
- Liposarcoma NOS.
Detail section
Normal mature fat
Microscopic
Features:
- Adipocytes of approximately equal size.
- Not vascular.
- No nuclear hyperchromasia.
Notes:
- May have nuclear pseudoinclusions (Lockhern cell)[2] - there is some suggestion this is not benign.Cite error: Closing
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Lipoma
General
- Benign.
- Several variants exist.
- Angiolipoma - one of the (classically) painful skin lesions.
Microscopic
Features:
- Collection of mature adipocytes.
- Variation of size may be seen -- should prompt a search for lipoblasts.[3]
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).[4]
Notes:
- May overlap with spindle cell lipoma.[5]
Hibernoma
General
- Consists of brown fat (present in the infants to generate heat).[6]
- Benign.
- Usually asymptomatic.[7]
Epidemiology
- Young adults.
Gross
- Well-circumscribed.
- Lobulated and light-brown on sectioning.
Microscopic
Features:[8]
- Large polygonal/oval cells:
Image:
Atypical lipomatous tumour
- AKA well-differentiated liposarcoma, abbreviated WDLPS.
- Abbreviated ALT/WDLPS.
General
- Atypical lipomatous tumour is a waffle diagnosis; it is like ASCUS.
Microscopic
Features:[11]
- Large adipocytes.
- Atypical lipoblasts - focal, scattered:
- Nuclear hyperchromasia.
- +/-Multinucleated.
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:
Subtypes
There are several subtypes:[1]
- Dedifferentiated liposarcoma.
- Myxoid liposarcoma.
- Mixed-type liposarcoma.
- Pleomorphic liposarcoma.
- Liposarcoma not otherwise specified (NOS).
IHC
- IHC is of limited value.
- S-100 +ve ~1/3 of the time.
- Reticulin ???.
See also
References
- ↑ 1.0 1.1 1.2 1.3 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 601. ISBN 978-0781765275.
- ↑ URL: http://journals.lww.com/amjdermatopathology/Citation/2004/12000/Original_Observation_to_Rediscovery__Nuclear.9.aspx. Accessed on: 18 April 2011.
- ↑ PMID 8548119.
- ↑ URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970321-7. Accessed on: 4 December 2010.
- ↑ URL: http://surgpathcriteria.stanford.edu/softfat/spindle_cell_lipoma/. Accessed on: 4 December 2010.
- ↑ 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.
- ↑ 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.
- ↑ Chen DY, Wang CM, Chan HL (March 1998). "Hibernoma. Case report and literature review". Dermatol Surg 24 (3): 393–5. PMID 9537018.
- ↑ http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6
- ↑ http://surgpathcriteria.stanford.edu/softfat/hibernoma/
- ↑ 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.