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.

Lipoma

General

• Benign.

Microscopic

Features:

• Collection of mature adipocytes.

Notes:

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

Hibernoma

General

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

Epidemiology

• Young adults.

Gross

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

Microscopic

Features:

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

Image:

• Hibernoma (WC).

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:

• Myxoid liposarcoma (WC).
• Myxoid liposarcoma (WC).
• Lipoblasts (john-libbey-eurotext.fr).

IHC

• IHC is of limited value.

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

See also

• Soft tissue lesions.
• Bone.