Msck soft tissue tumours

Question 1

Epi of Rahbdomyosarcoma

Answer 1

Most common soft tissue Sarcoma
of children

Question 2

Varients of Rhamdomyosarcoma

Answer 2

1) Pleomorphic Rhabdomyosarcoma
2) Embryonal Rhabdomyosarcoma
3) Alveolar Rhabdomyosarcoma

Question 3

Microscopic featurs:
* Typical rhabdo-myoblasts with eccentric eosinophilic cytoplasm
* high cellularity
* “Cambium layer” of tightly packed tumour cells beneath the epithelium

features of?

Answer 3

Embryonal Rhabdomyosarcoma (of the SM)

Question 4

Embryonal Rhabdomyosarcoma

Microscopic featurs:
* Typical rhabdo-myoblasts with eccentric eosinophilic cytoplasm
* high cellularity
* “————–” of tightly packed tumour cells beneath the epithelium

* eccentric : deviating away from the center

Answer 4

Microscopic featurs:
* Typical rhabdo-myoblasts with eccentric eosinophilic cytoplasm
* high cellularity
* “Cambium layer” of tightly packed tumour cells beneath the epithelium

Question 5

Microscopic features:
* Tumour cells line hollow spaces
* Fibro-vascular septa
* “Picket fence”-like arrangement

features of?

Answer 5

Alveolar Rhabdomyosarcoma

Question 6

Alveolar Rhabdomyosarcoma

Microscopic features:
* Tumour cells line hollow spaces
* Fibro-vascular septa
* “————–”-like arrangement

Answer 6

Microscopic features:
* Tumour cells line hollow spaces
* Fibro-vascular septa
* “Picket fence”-like arrangement

Question 7

Genetic confirmation of Synovial Sarcoma?

Answer 7

X;18 chromosomal translocation

(important for confirmation of the diagnosis but not specific for Synovial Sarcoma)

Question 8

location of Synovial Sarcoma

Answer 8

▪ Lower extremities (most common)
▪ Tissue adjacent to a joint, rather than in a joint cavity

Question 9

Synovial Sarcoma

Microscopic features:
▪ Either biphasic growth pattern; ——— and ——- cells
▪ Or monophasic pattern; only ——— cells component present

Answer 9

▪ Either biphasic growth pattern; both epithelial and spindled cells
▪ Or monophasic pattern; only the spindled component present

Question 10

Microscopic features
▪ Either biphasic growth pattern; both epithelial and spindled cells
▪ Or monophasic pattern; only the spindled component present

features of?

Answer 10

Synovial sarcoma

Question 11

Benign Fibrous Histocytoma is aka?

Answer 11

Dermatofibroma

Question 12

Macroscopic Features:
- Circumscribed, small (<1cm) mobile nodules, in the dermis or subcutaneous tissue

Microscopic Findings:
- Bland, spindle cells admixed with histiocyte-like cells

features of?

Answer 12

Dermatofibroma
(Benign Fibrous Histocytoma)

Question 13

Benign Fibrous Histiocytoma (Dermatofibroma)

Macroscopic Features:
- Circumscribed, small (<1cm) mobile nodules, in the dermis or subcutaneous tissue

Microscopic Findings:
- Bland, spindle cells admixed with ———-cells

Answer 13

Macroscopic Features:
- Circumscribed, small (<1cm) mobile nodules, in the dermis or subcutaneous tissue

Microscopic Findings:
- Bland, spindle cells admixed with histiocyte-like cells

Question 14

location of Undiffrentiated Pleomorphic sarcoma

Answer 14

Musculature of the proximal extremities or retroperitoneum

Question 15

Macroscopic Features:
▪ Large tumours (5-20cm)
▪ Gray-white, un-encapsulated lesions

Microscopic Findings:
▪ Storiform architecture (spiral appearance)
▪ Prominent cytologic pleomorphism
▪ Presence of bizarre multinucleate cells

features of?

Answer 15

Undifferentiated Pleomorphic Sarcoma

Question 16

Epi of Fibrosarcoma

Answer 16

Most common in adults

Question 17

Loc of Fibrosarcoma

Answer 17

Deep tissues of the thigh, knee and retro-peritoneum

Question 18

Macroscopic Features:
▪ Soft, un-encapsulated, infiltrative mass
▪ Cut-surface: Areas of haemorrhage and necrosis

Microscopic Findings:
▪ Spindle cells growing in a herring-bone fashion
▪ Possible presence of myxoid stroma
▪ High mitotic index and necroses

features of?

Answer 18

Fibrosarcoma

Question 19

Progression of Fibrosarcoma

Answer 19

▪ Slow growth (over several years)
▪ Local recurrence (>50% of cases)
▪ Haematogenous dissemination (>25% of cases), usually to the lungs

Question 20

——: Benign tumour of mature adipose tissue

Answer 20

Lipoma

Question 21

epi of Lipoma

Answer 21

Most common soft tissue tumour in adults

Question 22

Macroscopic Features:
- Soft, yellow, well encapsulated (demarcated) mass

Microscopic Findings:
- Mature, Uniform white fat cells (Uniform adipocytes)
- Thin collagenous pseudo-capsul
- No pleomorphism

features of?

Answer 22

Lipoma

Question 23

CM of Lipoma

Answer 23

• Mobile, slowly enlarging, painless mass
• Angiolipomas can manifest with local pain

Question 24

location of Liposarcoma

Answer 24

Deep soft tissues or retro-peritoneum

Question 25

# Genetic predispostion **Well-differentiated Liposarcomas** --> Amplification of a region of **-----** (containing the **---------** gene)

Answer 25

**Well-differentiated Liposarcomas** --> Amplification of a region of **12q** (containing the **-MDM2** gene)

Question 26

# Genetic Predisposition **Myxoid/Round Cell Liposarcomas** --> **t(--;--)** chromosomal translocation

Answer 26

**Myxoid/Round Cell Liposarcomas** --> **t(12;16)** chromosomal translocation

Question 27

Macroscopic Features: - Relatively **well-circumscribed** lesion Microscopic Findings: - Significant **variation in adipocyte siz** - Presence of **lipoblasts**, with **cytoplasmic lipid vacuoles** that scallop the nucleus and appearance similar to **fetal fat cells** - Focal nuclear Atypia featrues of?

Answer 27

Liposarcoma

Question 28

The 2 varients of Liposarcoma

Answer 28

▪ Low-Grade variant --> Well-differentiated Liposarcoma ▪ High-Grade variant --> Myxoid/Round Cell Liposarcoma

Question 29

Macroscopic features: - Prominent **high water myxoid component** - Small lipomatous component - Gelatinous yellowish appearance with **red-tinged foci** Microscopic features: - Low cellularity - **Uniform oval tumour cells** - Prominent, **branching capillary pattern** - Variable numbers of **non-atypical adipocytes** features of?

Answer 29

Myxoid Liposarcoma