L45 Soft tissue tumors

Question 1

Soft tissue tumors are ________________ lesions occurring in extra-skeletal & non-epithelial tissues of body.

Answer 1

Mesenchymal proliferative lesions

Question 2

Which type of soft tissue tumors occur from birth to 15 years old?

Answer 2

Rhabdomyosarcoma

Question 3

Malignant fibrous histiocytoma tends to occur at young age (20-40).
T/F?

Answer 3

Rhabdomyosarcoma
> Synovial sarcoma 
> fibrosarcoma
> liposarcoma
> malignant schewannoma
> malignant fibrous histiocytoma

Question 4

What are the 4 main etiologies other than idiopathic for soft tissue tumors?

Give examples for each ethology.
(4+4)

Answer 4

1. Genetics: germline mutation e.g. NF-1, NF2
2. Oncogenic virus
   e. g. HHV-8 infection causing Kaposi sarcoma
3. Ionising radiation, e.g. malignant fibrous histiocytoma
4. Chemical: vinyl chloride (liver angiosarcoma)

Question 5

__________ is done to define the nature of the soft tissue tumor and for therapeutic guide.

How the diagnosis is made? (3)

Answer 5

Biopsy

1. Histomorphological features
2. Immunohistochemistry
3. Molecular/cytogenic study

Question 6

List how the soft tissue tumors are staged.

Answer 6

TNM staging

T: Tumor size
T1 <5cm ; T2 >5cm
Lymph node: N0,N1
Metastasis: M0, M1

\+ grading 
Stage I: G1, T1/T2, N0,M0
Stage II: G2, T1/T2, N0,M0
Stage III: G3, 1/T2, N0,M0
Stage IV: G4, 1/T2, N0/N1,M1

Question 7

How soft tissue tumors are graded? (not staging!)

Answer 7

depends on

• cellularity
• pleomorphism
• mitosis
• necrosis
• growth pattern (expansive VS infiltrative growth)

Question 8

Name the 2 types of fibrohistiocytic tumors.

Answer 8

1. Dermatofibroma
   - bengin
2. Malignant fibrous histiocytoma
   - malignant, associated with radiation
   - MC sarcoma in adults

Question 9

What is the MC sarcoma in adults with high mortality rate?

Answer 9

Malignant fibrous histiocytoma (MFH)

Question 10

Name the MC benign soft tissue tumor.

Describe its characteristics.

Answer 10

Lipoma

- encapsulated mass of mature adipocytes

Question 11

What is the 2nd most common sarcoma in adults?

Answer 11

Liposarcoma

- malignant, deep seated, variable aggressiveness

Question 12

How to treat liposarcoma?

Answer 12

Wide excision, but tend to recur

Question 13

Name the 2 smooth muscles related soft tissue tumor.

Answer 13

1. Leiomyoma (benign)

2. Leiomyosarcoma (malignant)

Question 14

Where are the common sites of leiomyoma?

Answer 14

1. Uterus

2. Less in GI, skin

Question 15

What are the 2 skeletal muscles related soft tissue tumors?

Answer 15

1. Rhabdomyoma

2. Rhabdomyosarcoma

Question 16

Rhabdomyoma is benign and is associated with?

Answer 16

Tuberous sclerosis

Question 17

MC sarcoma of childhood and adolescence?

Answer 17

Rhabdomyosarcoma

Question 18

What are the 3 types of rhabdomyosarcoma?

Answer 18

1. Embryonic type: <10 years old, in head and neck, GU, trunk
2. Alveolar type:
   - early to mid-adolescence, in deep musculature of extremities
   - t(2;13)
3. Pleomorphic type
   - adults
   - deep soft tissues

Question 19

Name the 3 types of peripheral nerve sheath tumors.

Answer 19

1. Schwannoma (benign and encapsulated)
   2 . Neurofibroma (benign)
2. Malignant peripheral nerve sheath tumor

Question 20

Schwannoma is an encapsulated benign tumor. What can be observed in histology?

Answer 20

Antoni A (hypercellular)
Antoni B (hypocellular)

Question 21

Neurofibroma is sporadic, can appear in skin or peripheral nerves.
What are the types of neurofibromatosis? What chromosomal changes are involved in each type/

Answer 21

1. NF1: 17q11.2
   - possible malignant transformation
2. NF2: 22q12
   - associated with bilateral acoustic schwannoma and CNS tumors (multiple meningiomas, spinal gliomas)

Question 22

Malignant peripheral nerves sheath tumor is sporadic, with poor prognosis.

It arises from the background of?

Answer 22

neurofibromatosis

Question 23

2 types of vascular type of soft tissue tumors?

Answer 23

1. Hemangioma (benign)

2. Angiosarcoma (malignant, poor prognosis)

Question 24

Synovial sarcoma usually at where?

Benign/malignant?

Answer 24

Large joint of extremities, but can also develop in other locations, e.g. chest wall.

Malignant
- slow-growing, deep-seated mass

Question 25

Synovial sarcoma
What pattern?

What gene?

Answer 25

Biphasic pattern
- Epithelial cells + spindle cells +/- calcification

Typical t(X,18) and fusion gene (SYT-SSX)