← All patterns
Soft-tissue mass
MSKMRI / US
A mass in the soft tissues. Most are benign; specific signal characteristics (fat, fluid, flow voids) allow confident diagnosis, while non-specific solid masses need biopsy.
Differential
Lipoma
common- •Follows subcutaneous fat on all sequences, suppresses on fat-sat
- •No/thin septa, no nodular enhancement
Ganglion / synovial cyst
common- •Well-defined fluid signal near a joint/tendon sheath
- •Thin wall, no internal enhancement
Haemangioma / vascular malformation
less-common- •Serpentine vessels, phleboliths, fat overgrowth
- •Very T2-bright with fluid–fluid levels
Peripheral nerve sheath tumour
less-common- •Fusiform mass along a nerve with entering/exiting nerve
- •Target sign and split-fat sign; neurofibromatosis
Myxoid tumour (e.g. myxoma)
rare- •Markedly T2-bright, low T1, mild internal enhancement
- •Intramuscular; Mazabraud with fibrous dysplasia
Soft-tissue sarcoma
rare- •Large (>5 cm), deep, heterogeneous with necrosis
- •Nodular enhancement; growth over time
Key discriminators
- •Fat content (lipoma) and fluid signal (cyst)
- •Flow voids / phleboliths (vascular)
- •Relationship to a nerve (target and split-fat signs)
- •Size, depth and heterogeneity (sarcoma risk)
- •Nodular enhancement and interval growth
Work-up / next steps
- 1.MRI with and without contrast for tissue characterisation
- 2.Ultrasound for superficial/cystic lesions
- 3.Refer indeterminate or deep >5 cm masses to a sarcoma unit before biopsy
- 4.Image-guided core biopsy along a planned resection path
References
- Radiopaedia: Soft tissue masses.
- Kransdorf MJ, Murphey MD. Imaging of Soft Tissue Tumors.
Educational clinical decision support only. This differential does not make a diagnosis, is not a medical device, and must never substitute for interpretation by a qualified radiologist correlated with the full clinical picture and prior imaging.