Pathology of MSK Tumours I

Question 1

What are some practical issues associated with MSK tumours?

Answer 1

When and what to biopsy, don’t send a fine needle aspirate from a superficial 10cm mass, diagnosis relies on examination of all of lesion as well as other tests and radiological correlation

Question 2

What are soft tissue lesions characterised by?

Answer 2

Genetic abnormalities

Question 3

What is karyotyping?

Answer 3

Culture cells and then arrest during cell division, can be issues with quality of cells, useful overview of chromosomal structure, will not detect small or subtle lesions

Question 4

What is FISH?

Answer 4

Useful for known translocations, can “paint” relevant small area of chromosomes, if signals move together then its translocation, can be done on fixed tissue

Question 5

How is immunohistochemistry used?

Answer 5

Know certain cells express certain proteins, pigment placed on the antibody to target protein, any pigment staining left means the protein is present

Question 6

What are some examples of benign tumours?

Answer 6

Ganglion cyst, superficial fibromatoses, deep fibromatosis, giant cell tumour, fibrous cortical defect, fibrous dysplasia

Question 7

Where do ganglion cysts tend to form?

Answer 7

Peripheral and near joint capsule/ tendon sheath, common around wrist

Question 8

Why do ganglion cysts form?

Answer 8

Due to degenerative changes within the connective tissue

Question 9

Why are ganglion cysts not true cysts, and how they appear histologically?

Answer 9

They have no epithelial lining; space with myxoid material, secondary inflammatory changes

Question 10

What are some examples superficial fibromatoses?

Answer 10

Dupuytren’s = common, more common in men, average age is 60, idiopathic lots of associations (alcohol, diabetes, anticonvulsants)
Knuckle pads, Plantar, Penile (Peyronie’s)

Question 11

What are some features of deep fibromatosis?

Answer 11

Mesenteric or pelvic, desmoid tumours, associated with Gardner’s syndrome (FAP)

Question 12

What are some examples of giant cell tumours?

Answer 12

Pigmented villonodular synovitis = large joints, more destructive and diffuse in joint space, difficult to excise and often recur
Giant cell tumour of tendon sheath = digits, small nodules and easily excised, occasional recurrence

Question 13

Where are the nuclei of fat cells?

Answer 13

At the edge of the cell (are small)

Question 14

What are some features of an angiolipoma?

Answer 14

Usually multiple and peripheral, vascular with fibrin thrombi, painful subcutaneous lesion

Question 15

What are the components of the ANGEL acronym for types of fat tumours?

Answer 15

Angiolipoma, Neuroma (traumatic), Glomus tumour (nail beds etc), Eccrine spiradenoma (skin adnexal tumour), cutaneous Leiomyoma (of erector pilae)

Question 16

What are some tumours that can arise from smooth muscle?

Answer 16

Leiomyomas = one of most common tumours in body
Leiomyosarcomas = uncommon
Both may grow from large vessel walls

Question 17

What are present on IHC of smooth muscle tumours?

Answer 17

Actin, desmin, caldesmon

Question 18

What are the benign tumours that can form in skeletal muscle?

Answer 18

Rhabdomyomas = very rare, cardiac only found in children, head and neck are uncommon but found in older patients

Question 19

What are some features of embryonal rhabdomyosarcoma?

Answer 19

Occurs in childhood, genital tract (botyroides), GU tract, head and neck (periorbital) and common bile duct are all sites, caused by deletion Xp11.15

Question 20

What are some features of alveolar rhabdomyosarcomas?

Answer 20

Young adults, has many sites, caused by PAX translocation (t2:5)

Question 21

What are some features of pleomorphic rhabdomyosarcoma?

Answer 21

Rarest form, older age group, MYOD1 and myogenin on IHC

Question 22

What tumours occur in cartilage?

Answer 22

Sarcomas

Question 23

What age group tends to get cartilage sarcomas, and what are the exceptions?

Answer 23

Tend not to affect paediatrics and is more common in patients age 40-50; exceptions are clear cell and mesenchymal sarcomas

Question 24

Where to cartilage sarcomas tend to develop?

Answer 24

Axial skeleton and head and neck

Question 25

What are the malignant bone tumours called, and who tends to get them?

Answer 25

Osteosarcomas; paediatric age group in long bones

Question 26

How can osteosarcomas be predicted?

Answer 26

From destructive radiology (Codman’s triangle)

Question 27

What is the rule for diagnosing osteosarcomas?

Answer 27

Any tumour that produces osteoid is and osteosarcoma until proven otherwise

Question 28

What are two tumours of unknown origin?

Answer 28

Synovial and Ewing’s sarcomas

Question 29

Who gets Ewing’s sarcomas, and where do they tend to develop?

Answer 29

Occur in children and adolescents in any soft tissue or bony location (often long bones in adolescents)

Question 30

What are some features of Ewing’s sarcoma?

Answer 30

Destructive, rapidly growing, highly malignant, uncertain histogenesis, either primitive mesenchymal or neuroectodermal in origin, small round blue tumour cells

Question 31

What genetic abnormality causes Ewing’s sarcoma?

Answer 31

t(11;22)(EWS-FL11)

Question 32

What is the most common group of adult malignancies?

Answer 32

Carcinomas

Question 33

What are some indications that a tumour is a sarcomatoid carcinoma?

Answer 33

Look for dysplasia, can express any protein, often actin positive, look hard for epithelial markers (also positive in epitheloid and synovial sarcomas)

Question 34

What are some conditions that may be mistaken for sarcomatoid carcinomas?

Answer 34

Pseudosarcomas, tissues undergoing repair (may look atypical)

Question 35

What are some examples of reactive lesions?

Answer 35

Nodular fasciitis, myositis ossificans, rheumatoid, Heberden’s nodes, Buscchard’s nodes,, gouty tophi, abscesses, inflammatory myofibroblastic tumours

Question 36

What are some features of nodular fasciitis?

Answer 36

Any age group, rapid growth, small, sometimes history of trauma, very chaotic appearance, haemorrhage, pseudocystic spaces, large atypical cells, frequent and normal mitoses

Question 37

What are some features of myositis ossificans?

Answer 37

Reactive small and short history, preceding trauma, occurs in big muscles (quadriceps, gluteus), shows zonation

Question 38

What are some features of rheumatoid?

Answer 38

Nodules common, can occur in elbow, necrobiotic granulomatous inflammation

Question 39

What are some differentials for rheumatoid?

Answer 39

Deep granuloma annulare, epitheloid sarcoma

Question 40

What are some features of the cytology of connective tissue diseases?

Answer 40

Joint fluid examined under cross-polarised light to detect crystals, crystals lost during processing and formalin, need fresh specimen to diagnose with microscopy, negative birefringence (needle shaped crystals)

Question 41

What does cytology of connective tissue diseases show?

Answer 41

Amorphous eosinophilic debris and inflammation

Question 42

How does amyloid protein appear when using birefringence?

Answer 42

Apple green birefringence with congo red staining