Flashcards in Soft Tissue Tumors Deck (48)
What are soft tissue tumors?
Nonepithelial extra skeletal tumors
Exclude: reticuloendothelial system, glia and supporting tissue of parenchymal organs
Mesenchymal tumors are classified according to the tissue they recapitulate (muscle, fat, fibrous tissue, vessels and nerves)
What is the cause of most soft tissue tumors?
Unknown -- majority occur sporadically.
Association following radiation therapy.
Rare instances following chemical burns, thermal burns or trauma.
Are any soft tissue tumors genetically associated?
Neurofibromatosis type 1 -- neurofibroma, malignant schwannoma
Gardner syndrome -- fibromatosis
Li-Fraumeni syndrome -- soft tissue sarcomas
Osler-Weber-Rendu syndrome -- telangiectasia
Where do the majority of sarcomas occur?
About 40% occur in the lower extremities, especially the thigh.
What types of of sarcomas tend to appear in childhood? Young adulthood? Later adulthood?
Young adulthood: Synovial Sarcoma
Later adultlife: Liposarcoma and pleomorphic or undifferentiated sarcomas
What are a couple of important diagnostic features for soft tissue tumors?
What is the grading for soft tissue sarcoma based on?
Degree of differentiation/pleomorphism
Average number of mitoses per high-power field
Extent of necrosis (presumably a reflection of rate of growth)
What other prognostic factors are important to consider?
Size (> or < 5cm)
Depth (above or under fascia)
In general, tumors arising in superficial locations have better prognosis than deep lesions.
What is the treatment for soft tissue sarcomas?
Usually treated with wide surgical excision (frequently limb-sparing)
Irradiation and systemic therapy reserved for large high-grade tumors.
Malignant peripheral nerve sheath tumor (MPNST)
Smooth Muscle: leiomyoma, leiomyosarcoma
Skeletal Muscle: Rhabdomyoma, Rhabdomyosarcoma
PVNS, myositis ossificans, angiofibroma
Synovial sarcoma, alveolar soft part sarcoma, epithelioid sarcoma
What is the most common soft tissue tumor of adulthood?
What are some characteristics of conventional lipomas?
The most common subtype
Soft, yellow, well-encapsulated masses
What is the histology of conventional lipomas??
Consist of mature white fat cells with no pleomorphism
What is the genetic alteration in conventional lipomas?
What is one of the most common sarcomas of adulthood?
Where are liposarcomas generally located?
Deep soft tissues of proximal extremities and retroperitoneum, may develop into large tumors
How can liposarcomas histologically present and what is there behavior?
Well-differentiated is relatively indolent
Myxoid/round cell type is intermediate
Pleomorphic variant usually aggressive and may metastasize
How does a lipoblast differ from mature adipocyte?
Smaller size, has vacuolated bubbles, nucleus seems to be closer to center of cell and pushed/indented by other cells around it -- indicates liposarcoma
What characterizes WD-LPS and myxoid/round LPS genetically?
WD-LPS: supernumerary ring chromosomes, amplification of 12q14-q15, containing MDM2
Myxoid/round LPS: t(12;16)(q13;p11)
What are pseudosarcomatous proliferations?
Reactive non-neoplastic lesions that develop in response to some form of local trauma or are idiopathic
Develop suddenly and grow rapidly
Hypercellularity, mitotic activity, and primitive appearance mimic sarcoma
What are two types of pseudosarcomatous proliferations?
Nodular fasciitis: deep dermis, subcutis, or muscle; several centimeters with poorly defined margins
Myositis ossificans: proximal extremities, young adults, trauma in >50% of cases; presence of metaplastic bone-- eventually the lesion ossifies and the intertrabecular spaces become filled with bone marrow. Must be distinguished from extraskeletal osteosarcoma.
What are fibromatoses?
Benign soft tumors with similar characteristics
Examples of superficial fibromatosis
Palmar (Dupuytren contracture)
Penile (Peyronie disease)
May stabilize and resolve spontaneously. Some recur.
Some characteristics of deep-seated fibromatosis (desmoid tumors)
Behavior lies between benign fibrous tumors and low-grade fibrosarcomas
Frequently recur after incomplete excision
Most frequent in the teens to 30s
Some associated with Gardner syndrome
Mutations in APC or B-catenin genes