Soft Tissue and Joint Tumors Flashcards

1
Q

What are mesenchymal proliferations that occur in the extraskeletal non-epithelialized tissues of the body, excluding the joints, nervous system, hematologic tissue and lymphatic system?

A

soft tissue tumors

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2
Q

What is the name of malignant soft tissue tumors?

A

sarcomas

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3
Q

What is more common, benign or malignant soft tissue tumors?

A

Benign tumors are 100X more common

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4
Q

Where do the majority of soft tissue tumors arise?

A

thigh (extremities)

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5
Q

Tumor-like conditions in joints are most likely due to what?

A

trauma or degenerative processes

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6
Q

What is the name for small (1-1.5cm) ) cyst-like lesions that are almost always located near a joint capsule or tendon sheath?

A

ganglions

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7
Q

True or false: ganglions are highly related to ganglia of the nervous system.

A

FALSE- they have nothing to do with the nervous system.

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8
Q

What exactly is a ganglion?

A

degenerative phenomenon that leave spaces that are filled with myxoid fluid

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9
Q

Where are ganglions most commonly found? What do they feel like?

A

pea-sized nodule located around the wrist joint

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10
Q

Do ganglions have communication with the joint space?

A

NO

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11
Q

What is the slang term for a ganglion? Why is it called this?

A

Bible bump (called this because when hit hard with heavy book, it goes away)

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12
Q

How do you treat a ganglion?

A

needle aspiration or surgery

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13
Q

What tumor-like condition is caused when there is herniation of synovium through a joint capsule or enlargement of a bursa?

A

synovial cysts

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14
Q

What is a Baker cyst?

A

synovial cyst that forms in the popliteal space in the setting of RA

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15
Q

Describe the synovial lining of a Baker cyst.

A

hyperplastic and contains inflammatory cells/fibrin

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16
Q

What is the term for benign neoplasms that develop in the synovial lining of joints, tendon sheaths, and bursae?

A

Tenosynovial giant cell tumor

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17
Q

What are the two types of Tenosynovial giant cell tumor? Where do they most commonly occur?

A

Diffuse type- involves large joints

Localized type- occurs as a discrete nodule attached to a tendon sheath (commonly in the hand)

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18
Q

Who gets tenosynovial giant cell tumors?

A

young adults in 20s, 30s, 40s

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19
Q

What causes tenosynovial giant cell tumors?

A

chromosomal translocation of a (type VI collagen alpha-3) promoter that turns on synthesis of M-CSF that causes a proliferation of macrophages, some multinucleated, in a manner similar to giant cell tumor of bone.

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20
Q

How does the gross appearance of diffuse tenosynovial giant cell tumors differ from the localized counterparts?

A

Diffuse: normally smooth joint synovium is converted into a tangled mat by red-brown folds, finger-like projections, and nodules
Localized: well circumscribed

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21
Q

True of false: neoplastic cells only make up less than 25% of the cells in a tenosynovial giant cell tumor?

A

TRUE! only 2-16% (polygonal, moderately sized, look like synoviocytes)

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22
Q

Where are neoplastic cells found in a nodular tenosynovial giant cell tumor?

A

grow in solid aggregate that may be attached to the synovium by a pedicle

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23
Q

What cell type is in high concentrations in tenosynovial giant cell tumors?

A

macrophages

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24
Q

Where is tenosynovial giant cell tumor most commonly found?

A

knee

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25
Q

What is the most common soft tissue tumor of adulthood?

A

lipoma

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26
Q

What is a lipoma?

A

benign tumor of fat

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27
Q

What is the most common subtype of lipoma? Describe it.

A

conventional lipoma (well encapsulated mass of mature adipocytes)

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28
Q

Where do conventional lipomas usually arise?

A

subcutis of proximal extremities or trunk

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29
Q

What type of lipoma is associated with pain?

A

angiolipoma

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30
Q

Where do liposarcomas most commonly occur?

A

deep soft tissues of the proximal extremities and in the retroperitoneum

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31
Q

What are the three morphologic subtypes of liposarcoma?

A

1) Well-diferentiated
2) Myxoid
3) Pleomorphic

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32
Q

Describe well-differentiated liposarcoma.

A

adipocytes + scattered atypical spindle cells

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33
Q

Describe myxoid liposarcoma.

A

abundant basophilic extracellular matrix, arborizing capillaries, and primitive cells at various stages of adipocyte differentiation remniscent of fetal fat

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34
Q

Describe pleomorphic liposarcoma.

A

sheets of anaplastic cells, bizarre nuclei, variable numbers of immature adipocytes

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35
Q

Amplification of what gene is characteristic of well-differentiated liposarcomas?

A

12q13-q15 –> MDM2 (potent inhibitor of p53)

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36
Q

Amplification of what gene is characteristic of myxoid liposarcomas?

A

t(12;16) –> MDM2 (potent inhibitor of p53)

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37
Q

What type of liposarcomas have a more agressive behavior (metastasize)?

A

pleomorphic variant

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38
Q

What type of liposarcoma has the least aggressive behavior?

A

well-differentiated

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39
Q

What is a self-limited fibroblastic and myofibroblastic proliferation that typically occurs in young adults in the upper extremity, grows “rapidly” over a period of several weeks (or months), and rarely gets larger than 5 cm?

A

Nodular fasciitis

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40
Q

What is commonly present (25%) in patients with nodular fasciitis?

A

history of trauma

41
Q

What is the mutation commonly seen in nodular fasciitis?

A

t(17;22) that produces a MYH9-USP6 fusion gene

42
Q

Is nodular fasciitis a neoplasm?

A

defies classification as a neoplasm because it is clonal, but self-limited

43
Q

True of false: Nodular fasciitis typically spontaneously regresses.

A

True!

44
Q

What is the name of reactive bone formation in muscle as a result of injury (metaplastic repair response)?

A

Myositis ossificans

45
Q

What is the cause of myositis ossificans?

A

blunt trauma (mostly to the lower limb)

46
Q

What is the histiologic pattern of woven bone in myositis ossificans?

A

well-formed at the periphery but immature at the center

47
Q

What are the two forms of fibromatosis?

A

superficial and deep

48
Q

Which type of fibromatosis is an infiltrative fibroblastic proliferation that causes local deformity but has an innocuous clinical course?

A

Superficial

49
Q

What are two examples of superficial fibromatoses involving the hands?

A

Palmar fibromatosis

Dupuytren Contracture

50
Q

What are two examples of superficial fibromatoses involving the feet?

A

Plantar fibromatosis

Ledderhose disease

51
Q

What is the name of a fixed flexion contracture of the hand where the fingers bend towards the palm and cannot be fully extended (straightened)?

A

Dupuytren contracture

52
Q

What fingers are usually involved in Dupuytren contracture?

A

ring finger and pinky

middle finger in advanced cases

53
Q

Is Dupuytren contracture usually bilateral or unilateral?

A

50% bilateral

50% unilateral

54
Q

What really is a fibromatosis?

A

benign soft tissue tumor

55
Q

What is Peyronie disease?

A

a palpable induration or mass (penile fibromatosis) on the dorsolateral aspect of the penis

56
Q

What are complications of Peyronie disease?

A

abnormal curvature of the shaft, constriction of the urethra, or both

57
Q

What are examples of deep fibromatoses?

A

Desmoid tumors

Aggressive Fibromatoses

58
Q

Do deep fibromatoses metastasize?

A

NO

59
Q

How common are deep fibromatoses?

A

RARE

60
Q

Where do deep fibromatoses occur?

A

musculoaponeurotic structures of the anterior abdominal wall

61
Q

What is the cause of deep fibromatoses?

A

mutations in the APC or beta-catenin genes–> cause increased Wnt signaling

62
Q

What two groups of patients are predisposed to deep fibromatoses?

A

Gardner syndrome (familial adenomatous polyposis)

Germline APC mutations

63
Q

The histology of a deep fibromatoses resembles what?

A

a scar!

64
Q

How might you treat a deep fibromatosis?

A

cyclooxygenase 2 inhibitors, tyrosine kinase inhibitors, or hormonal blockade (with tamoxifen)

SURGERY is difficult because of the extent of infiltration.

65
Q

Do deep fibromatoses invade?

A

NO- they infiltrate

66
Q

What is a tumor of mesenchymal cell origin composed of malignant fibroblasts in a collagen background?

A

fibrosarcoma

67
Q

What is the word used to describe the fascicles of tumor cells oriented at alternating acute angles in fibrosarcoma?

A

“Herringbone” pattern

68
Q

What do fibrosarcoma tumor cells look like?

A

spindle shape with pointed ends (more or less).

69
Q

True or flase: because fibrosarcomas are derived from fibroblasts, the tumors are made of vast amounts of mature collagen.

A

FALSE: demonstrate relatively little mature collagen

70
Q

True or false: fibrosarcomas are painful.

A

True

71
Q

Where do fibrosarcomas occur in bone?

A

metaphysis of long bones and pelvis.

72
Q

Where do fibrosarcomas occur in soft tissue?

A

thigh

73
Q

What is a a non-cancerous growth of dermal dendritic histiocytic cells?

A

Dermatofibroma

74
Q

What might trigger a dermatofibroma?

A

site of minor injury (insect bite or thorn prick)

75
Q

Where do dermatofibromas most commonly form?

A

arms and legs

76
Q

What happens when you squeeze a dermatofibroma?

A

it forms a dimple (indicating tethering of the skin to the underlying fibrous tissue)

77
Q

What is a relatively uncommon soft tissue neoplasm with intermediate- to low-grade malignancy?

A

Dermatofibrosarcoma protuberans (DFSP)

78
Q

What subcutaneous fibrohistiocytic cellular proliferation is neoplastic and highly malignant?

A

undifferentiated pleomorphic sarcoma

79
Q

Where do UPS’s commonly arise?

A

deep soft tissues of the extremity, especially the thigh of middle aged or older adults

Can arise in retroperitoneum

80
Q

Where do UPS’s commonly metastasize?

A

Lung (90%)
Bone (8%)
Liver (1%)

81
Q

What is a malignant mesenchymal tumor with skeletal muscle differentiation?

A

Rhabdomyosarcoma

82
Q

What are the 3 subtypes of Rhabdomyosarcoma?

A

1) Alveolar (20%)
2) Embryonal (60%)
3) Pleomorphic (20%)

83
Q

Which type of rhabdomyosarcoma is more common in adults?

A

Pleomorphic rhabdomyosarcoma

84
Q

True or false: rhabdomyosarcomas arise from mature, terminally differentiated muscle cells.

A

FALSE!

(reinforced by the fact that pediatric forms arise in places that do not contain much skeletal muscle like head/neck, sinuses, GU tract)

85
Q

What type of rhabdomyosarcoma frequently contains fusions of the FOXO1 gene to either the PAX3 or the PAX7 gene, rearrangements marked by the presence of (2;13) or(1;13) translocations, respectively?

A

Alveolar

86
Q

What does the PAX3-FOXO1 fusion protein do in alveolar rhabdomyosarcoma?

A

interferes with the gene expression program that drives skeletal muscle differentiation

87
Q

What is the name for benign tumors of smooth muscle?

A

Leiomyoma

88
Q

What is the most common site of leiomyoma?

A

uterus

89
Q

Why do uterine leiomyomas tend to regress after menopause?

A

they are estrogen sensitive

90
Q

From what muscle may leiomyomas also arise?

A

erector pili muscles

91
Q

What are features of hereditary leiomyomatosis and renal cell cancer syndrome?

A

AD disease
Multiple cutaneous leiomyomas
Uterine leimyomas
renal cell carcinoma

92
Q

What is the cause of hereditary leiomyomatosis and renal cell cancer syndrome?

A

germline loss-of-function mutation in the fumarate hydratase gene located on chromosome 1q42.3

93
Q

What do soft tissue leiomyomas look like microscopically?

A

fascicles of densely eosinophilic spindle cells that tend to intersect each other at right angles

94
Q

Where do Leiomyosarcoma most commonly develop?

A

the deep soft tissues of the limbs and retroperitoneum

95
Q

What is a very lethal site of leiomyosarcomas?

A

IVC (or other great vessels)

96
Q

Leiomyosarcomas immunostain with what antibodies?

A

antibodies to SM actin and desmin

97
Q

How do sarcomas spread?

A

blood (hematogenous spread)

98
Q

Where is a very common site of metastasis for sarcomas?

A

LUNGS (capillary beds are rich there and filter them out–allowing htem to grow in lung tissue)

99
Q

In what part of the lungs are pulmonary mets from sarcomas most common?

A

basal lower lobes