Chondroid lipoma

Definition

A benign tumour composed of lipoblasts, mature adipocytes and a chondroid matrix.

Epidemiology

A tumour of adults, fourfold more common in women.

Clinical features

Found most commonly in the proximal extremities and limb girdles.

Macroscopic appearances

Yellow and fatty.

Histopathology

Often encapsulated, may be multilobated. There are cords or nests of vacuolated lipoblasts. Numbers of mature adipocytes vary. The stroma is myxoid to chondroid. There are often areas of haemorrhage and fibrosis.

Immunohistochemistry

• S-100 positive, strongly in adipocytes, weakly in lipoblasts

• Vimentin positive

• Cytokeratins rarely positive

• EMA negative

• MIB1 proliferation index < 1%

Ultrastructure

• Adipocytes, preadipocytes and lipoblasts

• Knobby cytoplasmic protrusions

• chondroid matrix with thin filaments and numerous proteoglycan particles

Differential diagnosis

• myxoid liposarcoma

• extraskeletal myxoid chondrosarcoma

Management

Surgical excision is curative.

References

World Health Organization Classification of Tumours, Tumours of Soft Tissues and Bone, IARC Press 2002.

This page last revised 25.6.2004.

©SMUHT/PW Bishop