Synonyms

• Fetal lipoma
• embryonal lipoma

Category

Soft tissue

Behaviour

Benign

Gender

Male

Tissue of Origin

Adipose

Epidemiology

• Benign embryonal white fat
• Presents in infants and young children
• 75-90% in patients younger than 3

Clinical Features

• Soft tissue mass
• Usually painless and Slow-growing
• May involve fascial compartments

Location

• Lower extremity most common
• Upper extremity
• Trunk

Imaging

• MRI: well-defined fat and myxoid components
• T2 bright areas mixed with lipid

Pathology

• Primitive mesenchymal cells and immature fat
• Myxoid stroma
• No atypia

Genetics

PLAG1 rearrangements common

Treatment

• Marginal excision curative
• Observation if asymptomatic

Prognosis

Excellent - no malignant potential

Key Points

• Embryonal fatty tumour of infants
• Benign despite somewhat immature appearance

Workup - Blood Tests

No blood tests required

Workup - Local Imaging

MRI - characterises extent and fat composition

Workup - Biopsy

Biopsy if diagnosis uncertain

Workup - Staging

No staging required

Workup - Other

Complete excision standard when feasible