Synonyms

FHOI

Category

Soft tissue

Behaviour

Benign

Gender

Both equally

Tissue of Origin

Fibrous

Epidemiology

• Benign mesenchymal hamartoma
• Presents in infants and young children
• Axilla most common site

Clinical Features

• Firm mass in axilla or groin
• Usually painless
• May enlarge but typically stops growing

Location

• Axilla (most common)
• Groin
• Buttock
• Upper extremity

Imaging

• Ultrasound: heterogeneous mass
• MRI: mixed lipid and Fibrous components

Pathology

Admixture of mature fat, Fibrous tissue, and primitive mesenchymal elements

Genetics

PLAG1-CHTOP fusion reported

Treatment

• Observation or marginal excision
• Some spontaneously regress

Prognosis

Excellent - no malignant potential

Key Points

• Benign hamartoma of infants
• Axilla is classic location
• Often no treatment needed

Workup - Blood Tests

No blood tests required

Workup - Local Imaging

Ultrasound or MRI for baseline characterisation

Workup - Biopsy

Rarely required

Workup - Staging

No staging required

Workup - Other

Observation standard of care