Soft Tissue and Joint Tumors Flashcards
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?
soft tissue tumors
What is the name of malignant soft tissue tumors?
sarcomas
What is more common, benign or malignant soft tissue tumors?
Benign tumors are 100X more common
Where do the majority of soft tissue tumors arise?
thigh (extremities)
Tumor-like conditions in joints are most likely due to what?
trauma or degenerative processes
What is the name for small (1-1.5cm) ) cyst-like lesions that are almost always located near a joint capsule or tendon sheath?
ganglions
True or false: ganglions are highly related to ganglia of the nervous system.
FALSE- they have nothing to do with the nervous system.
What exactly is a ganglion?
degenerative phenomenon that leave spaces that are filled with myxoid fluid
Where are ganglions most commonly found? What do they feel like?
pea-sized nodule located around the wrist joint
Do ganglions have communication with the joint space?
NO
What is the slang term for a ganglion? Why is it called this?
Bible bump (called this because when hit hard with heavy book, it goes away)
How do you treat a ganglion?
needle aspiration or surgery
What tumor-like condition is caused when there is herniation of synovium through a joint capsule or enlargement of a bursa?
synovial cysts
What is a Baker cyst?
synovial cyst that forms in the popliteal space in the setting of RA
Describe the synovial lining of a Baker cyst.
hyperplastic and contains inflammatory cells/fibrin
What is the term for benign neoplasms that develop in the synovial lining of joints, tendon sheaths, and bursae?
Tenosynovial giant cell tumor
What are the two types of Tenosynovial giant cell tumor? Where do they most commonly occur?
Diffuse type- involves large joints
Localized type- occurs as a discrete nodule attached to a tendon sheath (commonly in the hand)
Who gets tenosynovial giant cell tumors?
young adults in 20s, 30s, 40s
What causes tenosynovial giant cell tumors?
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.
How does the gross appearance of diffuse tenosynovial giant cell tumors differ from the localized counterparts?
Diffuse: normally smooth joint synovium is converted into a tangled mat by red-brown folds, finger-like projections, and nodules
Localized: well circumscribed
True of false: neoplastic cells only make up less than 25% of the cells in a tenosynovial giant cell tumor?
TRUE! only 2-16% (polygonal, moderately sized, look like synoviocytes)
Where are neoplastic cells found in a nodular tenosynovial giant cell tumor?
grow in solid aggregate that may be attached to the synovium by a pedicle
What cell type is in high concentrations in tenosynovial giant cell tumors?
macrophages
Where is tenosynovial giant cell tumor most commonly found?
knee
What is the most common soft tissue tumor of adulthood?
lipoma
What is a lipoma?
benign tumor of fat
What is the most common subtype of lipoma? Describe it.
conventional lipoma (well encapsulated mass of mature adipocytes)
Where do conventional lipomas usually arise?
subcutis of proximal extremities or trunk
What type of lipoma is associated with pain?
angiolipoma
Where do liposarcomas most commonly occur?
deep soft tissues of the proximal extremities and in the retroperitoneum
What are the three morphologic subtypes of liposarcoma?
1) Well-diferentiated
2) Myxoid
3) Pleomorphic
Describe well-differentiated liposarcoma.
adipocytes + scattered atypical spindle cells
Describe myxoid liposarcoma.
abundant basophilic extracellular matrix, arborizing capillaries, and primitive cells at various stages of adipocyte differentiation remniscent of fetal fat
Describe pleomorphic liposarcoma.
sheets of anaplastic cells, bizarre nuclei, variable numbers of immature adipocytes
Amplification of what gene is characteristic of well-differentiated liposarcomas?
12q13-q15 –> MDM2 (potent inhibitor of p53)
Amplification of what gene is characteristic of myxoid liposarcomas?
t(12;16) –> MDM2 (potent inhibitor of p53)
What type of liposarcomas have a more agressive behavior (metastasize)?
pleomorphic variant
What type of liposarcoma has the least aggressive behavior?
well-differentiated
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?
Nodular fasciitis
What is commonly present (25%) in patients with nodular fasciitis?
history of trauma
What is the mutation commonly seen in nodular fasciitis?
t(17;22) that produces a MYH9-USP6 fusion gene
Is nodular fasciitis a neoplasm?
defies classification as a neoplasm because it is clonal, but self-limited
True of false: Nodular fasciitis typically spontaneously regresses.
True!
What is the name of reactive bone formation in muscle as a result of injury (metaplastic repair response)?
Myositis ossificans
What is the cause of myositis ossificans?
blunt trauma (mostly to the lower limb)
What is the histiologic pattern of woven bone in myositis ossificans?
well-formed at the periphery but immature at the center
What are the two forms of fibromatosis?
superficial and deep
Which type of fibromatosis is an infiltrative fibroblastic proliferation that causes local deformity but has an innocuous clinical course?
Superficial
What are two examples of superficial fibromatoses involving the hands?
Palmar fibromatosis
Dupuytren Contracture
What are two examples of superficial fibromatoses involving the feet?
Plantar fibromatosis
Ledderhose disease
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)?
Dupuytren contracture
What fingers are usually involved in Dupuytren contracture?
ring finger and pinky
middle finger in advanced cases
Is Dupuytren contracture usually bilateral or unilateral?
50% bilateral
50% unilateral
What really is a fibromatosis?
benign soft tissue tumor
What is Peyronie disease?
a palpable induration or mass (penile fibromatosis) on the dorsolateral aspect of the penis
What are complications of Peyronie disease?
abnormal curvature of the shaft, constriction of the urethra, or both
What are examples of deep fibromatoses?
Desmoid tumors
Aggressive Fibromatoses
Do deep fibromatoses metastasize?
NO
How common are deep fibromatoses?
RARE
Where do deep fibromatoses occur?
musculoaponeurotic structures of the anterior abdominal wall
What is the cause of deep fibromatoses?
mutations in the APC or beta-catenin genes–> cause increased Wnt signaling
What two groups of patients are predisposed to deep fibromatoses?
Gardner syndrome (familial adenomatous polyposis)
Germline APC mutations
The histology of a deep fibromatoses resembles what?
a scar!
How might you treat a deep fibromatosis?
cyclooxygenase 2 inhibitors, tyrosine kinase inhibitors, or hormonal blockade (with tamoxifen)
SURGERY is difficult because of the extent of infiltration.
Do deep fibromatoses invade?
NO- they infiltrate
What is a tumor of mesenchymal cell origin composed of malignant fibroblasts in a collagen background?
fibrosarcoma
What is the word used to describe the fascicles of tumor cells oriented at alternating acute angles in fibrosarcoma?
“Herringbone” pattern
What do fibrosarcoma tumor cells look like?
spindle shape with pointed ends (more or less).
True or flase: because fibrosarcomas are derived from fibroblasts, the tumors are made of vast amounts of mature collagen.
FALSE: demonstrate relatively little mature collagen
True or false: fibrosarcomas are painful.
True
Where do fibrosarcomas occur in bone?
metaphysis of long bones and pelvis.
Where do fibrosarcomas occur in soft tissue?
thigh
What is a a non-cancerous growth of dermal dendritic histiocytic cells?
Dermatofibroma
What might trigger a dermatofibroma?
site of minor injury (insect bite or thorn prick)
Where do dermatofibromas most commonly form?
arms and legs
What happens when you squeeze a dermatofibroma?
it forms a dimple (indicating tethering of the skin to the underlying fibrous tissue)
What is a relatively uncommon soft tissue neoplasm with intermediate- to low-grade malignancy?
Dermatofibrosarcoma protuberans (DFSP)
What subcutaneous fibrohistiocytic cellular proliferation is neoplastic and highly malignant?
undifferentiated pleomorphic sarcoma
Where do UPS’s commonly arise?
deep soft tissues of the extremity, especially the thigh of middle aged or older adults
Can arise in retroperitoneum
Where do UPS’s commonly metastasize?
Lung (90%)
Bone (8%)
Liver (1%)
What is a malignant mesenchymal tumor with skeletal muscle differentiation?
Rhabdomyosarcoma
What are the 3 subtypes of Rhabdomyosarcoma?
1) Alveolar (20%)
2) Embryonal (60%)
3) Pleomorphic (20%)
Which type of rhabdomyosarcoma is more common in adults?
Pleomorphic rhabdomyosarcoma
True or false: rhabdomyosarcomas arise from mature, terminally differentiated muscle cells.
FALSE!
(reinforced by the fact that pediatric forms arise in places that do not contain much skeletal muscle like head/neck, sinuses, GU tract)
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?
Alveolar
What does the PAX3-FOXO1 fusion protein do in alveolar rhabdomyosarcoma?
interferes with the gene expression program that drives skeletal muscle differentiation
What is the name for benign tumors of smooth muscle?
Leiomyoma
What is the most common site of leiomyoma?
uterus
Why do uterine leiomyomas tend to regress after menopause?
they are estrogen sensitive
From what muscle may leiomyomas also arise?
erector pili muscles
What are features of hereditary leiomyomatosis and renal cell cancer syndrome?
AD disease
Multiple cutaneous leiomyomas
Uterine leimyomas
renal cell carcinoma
What is the cause of hereditary leiomyomatosis and renal cell cancer syndrome?
germline loss-of-function mutation in the fumarate hydratase gene located on chromosome 1q42.3
What do soft tissue leiomyomas look like microscopically?
fascicles of densely eosinophilic spindle cells that tend to intersect each other at right angles
Where do Leiomyosarcoma most commonly develop?
the deep soft tissues of the limbs and retroperitoneum
What is a very lethal site of leiomyosarcomas?
IVC (or other great vessels)
Leiomyosarcomas immunostain with what antibodies?
antibodies to SM actin and desmin
How do sarcomas spread?
blood (hematogenous spread)
Where is a very common site of metastasis for sarcomas?
LUNGS (capillary beds are rich there and filter them out–allowing htem to grow in lung tissue)
In what part of the lungs are pulmonary mets from sarcomas most common?
basal lower lobes
