Soft tissue tumors

Question 1

Internal features that are consistent with a simple lipoma

Answer 1

Thin, wispy septations

Question 2

Internal features that are not consistent with a simple lipoma

Answer 2

Thick, irregular septations
Septal or nodular enhancement
Bright on fluid-sensitive sequences

Question 3

Appearance of fat and fluid on PD weighted imaging

Answer 3

Bright

Question 4

Another name for a well-differentiated liposarcoma

Answer 4

Atypical lipomatous tumor (ALT)

Question 5

Well-differentiated liposarcomas can be locally aggressive but…

Answer 5

…rarely metastasize

Question 6

What specific tumors are characterized by the term “high-grade liposarcoma”?

Answer 6

De-differentiated liposarcoma
Pleomorphic liposarcoma

(cannot be distinguished on imaging)

Question 7

Appearance of necrosis on contrast-enhanced imaging

Answer 7

Non-enhancing

Question 8

Typical MRI features of high-grade liposarcoma

Answer 8

Heterogenous enhancement (due to central necrosis) 
Minimal or absent fatty elements

Question 9

Differential diagnosis

• mildly T2 bright mass
• heterogeneously enhancing (with central necrosis)
• minimal or absent fatty elements on T1

Answer 9

High grade liposarcoma
Undifferentiated pleomorphic sarcoma (UPS)
Rhabdomyosarcoma
Leiomyosarcoma

Question 10

Differential diagnosis

• prominently T2 bright mass
• heterogeneously enhancing
• minimal or absent fatty elements on T1

Answer 10

Myoxoid liposarcoma
Myxofibrosarcoma
Synovial sarcoma
Malignant peripheral nerve sheath tumor

Question 11

Characteristic imaging finding of a myxoid liposarcoma (compared to other liposarcomas)

Answer 11

Homogenously T2 bright

Question 12

Diagnosis

• rare benign tumor of peripheral nerves
• proliferation of fibrous and fatty tissue
• infiltration of epineurium and perineurium

Answer 12

Fibrolipomatous hamartoma

Question 13

Most common peripheral nerve affected by fibrolipomatous hamartoma

Answer 13

Median nerve

Question 14

Pathognomonic imaging feature of a fibrolipomatous hamartoma

Answer 14

Cable-like appearance of the affected nerve

due to fatty proliferation between the fascicles

Question 15

What congenital disease are fibrolipomatous hamartomas associated with?

Answer 15

Macrodystrophia lipomatosa

• localized giantism of single digits
• caused by overgrowth of fibroadipose tissue

Question 16

Another name for an undifferentiated pleomorphic sarcoma

Answer 16

Malignant fibrous histiosarcoma

Question 17

The two subtypes of superficial fibromatoses

Answer 17

Plantar and palmar

Palmar is more common, and occurs in older patients

Question 18

Characteristic MRI appearance of superficial fibromatosis

Answer 18

Nodular foci of variable signal intensity within the subcutaneous tissue

(variable amounts of fibrotic and cellular material)

Question 19

Another name for palmar fibromatosis

Answer 19

Dupuytren’s contracture

painless subcutaneous nodules that often require surgery

Question 20

Another name for plantar fibromatosis

Answer 20

Ledderhose disease

Question 21

Preferred management of plantar fibromatosis

Answer 21

Conservative (footwear modification, intra-lesional steroids)

Question 22

Most likely diagnosis

• benign, rapidly growing mass
• usually located in a muscle belly
• T2 bright and T1 enhancing

Answer 22

Nodular fasciitis

some pathologists consider them to be myxoid