Soft tissues

Question 1

What encompasses soft tissues?

Answer 1

Mesenchymal tissues excluding the central nervous system, bone and blood
–>Fibrous, adipose, muscle, vascular and neural tissue

Question 2

What is the general pathogenesis of soft tissue tumors?

Answer 2

Most of unknown etiology; Radiation/chemical carcinogen or genetic (neurofibromatosis) basis in some

Question 3

What is the behavior of soft tissue tumors?

Answer 3

Tumor grade – Very important prognostic factor (1 - 3)
Metastatic characteristics:
Lung is primary site of metastases
Hematogenous route more frequent than lymphatic
25% of sarcomas with lung metastases at diagnosis
Liver metastases uncommon except for intra-abdominal sarcomas
Lymph node metastases uncommon (

Question 4

What are the cytogenetics of soft tissue tumors generally?

Answer 4

• Most associated with a characteristic translocation or chromosomal abnormality that is present in the majority of given type tumor
• Diagnostic potential is significant
• Technically demanding procedure with tissue manipulation and interpretation difficulties of the result only allow diagnostic application to relatively few cases
• Poorly differentiated tumors are usual ones targeted for analysis – Establishing cell lineage important for treatment decisions
• Help indicate cell type for undifferentiatied tumors
• May have important prognostic implications

Question 5

What are clinical features of oral tissue benign tumors?

Answer 5

Uncommon, but all types can involve the oral cavity

Usually present as submucosal nodule, often slow growing

Question 6

Describe the tumors in the oral cavity-benign and malignant

Answer 6

Benign tumors’
Pyogenic granuloma – Reddish nodule; Lip most common location
Lipoma – Pretty uncommon in oral cavity; Yellow, soft nodule of buccal mucosa
Malignant tumors:
Malignant fibrous histiocytoma most common in oral cavity – Older patients
Malignant peripheral nerve sheath tumors
–At least 50% occur in patients with neurofibromatosis type 1 (NF1)
–Occur at younger ages and behave more aggressively in NF1
–Expansion of inferior alveolar nerve canal is characteristic radiographic finding

Question 7

What are some examples of oral cavity tumors?

Answer 7

Nodular Fasciitis:
Probably reactive in nature – Associated history trauma but only 15%
Regress spontaneously
Atypical histology/mitotic activity – difficult to distinguish from malignancy

Fibromatoses:
Benign tumors with variable behavior in respect to infiltrativeness/recurrence
Deep tissue based lesions behave more aggressively
Also known as “desmoid tumors”
Higher cellularity, decreased intercellular collagen and infiltrative growth distinguish from superficial fibromatoses
Gardner’s syndrome associated fibromatoses often aggressive

Question 8

what are features of fibrosarcoma?

Answer 8

Distinctive “herringbone pattern” and other malignant features (mitotic activity, etc.)

Question 9

What are features of pleomorphic fibroblastic sarcoma/pleomorphic undifferentiated sarcoma? (formerly known as malignant fibrous histiocytoma)

Answer 9

Fibroblastic differentiation
Large, uncircumscribed; usually in deep tissue of proximal extremities or retroperitoneum
Extremely aggressive, recur, and metastasize (30-50%)
Malignant cells appear to represent abnormal differentiation of fibroblast

Question 10

Describe the features and histology of lipoma

Answer 10

Most common soft tissue tumor
-Benign lesions - cure by resection (well circumscribed – rarely infiltrative)
-Location in superficial subcutaneous/subepithelial tissue
-Rare hereditary forms with multiple lipomas
Histology
-Composed of mature adipocytes without features distinguishing them from normal
Several types
-Angiolipoma – Peripheral vascular structures; Associated with pain
-Fibrolipoma, intramuscular, pleomorphic etc.

Question 11

Describe liposarcomas

Answer 11

Older patients generally
Retroperitoneal or deep soft tissues of extremities
Prognosis strongly related to grade

Histology
-Lipoblast is malignant cell and key to diagnosis
-Heterogeneous histologic appearance
-Well-differentiated, myxoid, pleomorphic and round-cell types
-Poorly-differentiated types may have little adipose character histologically – location, special studies (IHC, cytogenetics) important in establishing diagnosis
Poorly differentiated types can be very aggressive

Question 12

Describe rhabdosarcoma

Answer 12

Malignant tumor of skeletal muscle; rhabdomyoblast is malignant cell
Most common soft tissue tumor in children

Question 13

What are the three types of rhabdosarcoma?

Answer 13

1) Alveolar (kids) – t(2;13) translocation; Extremities
2) Embryonal (kids) – Head & neck, genital/urinary tract and retroperitoneum
3) Characteristic “cambium” layer at periphery of tumor
Pleomorphic – Adults

Question 14

What is a leiomyoma?

Answer 14

Benign smooth muscle tumor, esp in uterus (“fibroid”)

Question 15

What is a Leiomyosarcoma?

Answer 15

Malignant smooth muscle tumor
Uterus and all tissues (especially associated with vasculature outside uterus)
Increased mitoses, presence of necrosis, cellular atypia

Question 16

What is a Schwannoma (peripheral nerve tumor)?

Answer 16

Benign tumors without significant rate of conversion to malignancy
Well circumscribed tumors that generally arise eccentrically from nerve
Antoni A (cellular, palisading) and Antoni B (less cellular) areas

Question 17

What is a neurofibroma? (peripheral nerve tumor)

Answer 17

Benign with occasional progression to malignancy
Irregular masses (infiltrative) that arise centrally in nerve
Composed of benign cells with wavy nuclei; entrapped nerve twigs

Question 18

What are Malignant Peripheral Nerve Sheath Tumors? (peripheral nerve tumor)

Answer 18

50% spontaneous; 50% neurofibromatosis type 1 associated

Spindled cellular morphology; mitoses and necrosis indicate malignancy

Question 19

What is Type 1 neurofibromatosis? Genetics, features, etc.

Answer 19

Genetics:
-Mutation of NF1 gene on chromosome 17
-Autosomal dominant pattern of inheritance
-aka von Recklinghausen disease
Clinical features/Diagnostic features:
At least two of: Café-au-lait spots (>6); Neurofibromas (>2); Lisch nodules (>2); Optic glioma; Axillary freckling
Or one of above with 1st degree relative with NF1
Increased risk of glioma, meningioma and pheochromocytoma
Neurofibromas may occur anywhere – Skin, viscera, CNS, etc.
MPNSTs – 3% incidence in NF1

Question 20

What is Type 2 neurofibromatosis? Genetics, features, etc.

Answer 20

Genetics:
-NF2 gene mutated on chromosome 22
-Autosomal dominant pattern of inheritance
Clinical features:
Vestibular schwannomas (a/w CN VIII) are characteristic lesion – Bilateral tumors is diagnostic of NF2
Other diagnostic complexes
Family history + unilateral vestibular schwannoma
Family history + two of meningioma, glioma, schwannoma, cataracts
Malignant risk – Not prominent in NF2 (no increase incidence of MPNSTs)

Question 21

Describe Synovial Sarcomas

Answer 21

Clinical
10% of all sarcomas
May arise adjacent to joint, but also frequently arise in viscera or elsewhere
Cytogenetics – t(X;18) translocation is characteristic and present in large majority of synovial sarcomas
Histology
Biphasic (epithelioid and spindle cell components) or monophasic
High grade usually

Question 22

What is alveolar soft parts sarcoma?

Answer 22

Clinical
Rare but can involve oral cavity
Malignant tumors but slow growing
Young adults usually affected
Histology
Characteristic nested (alveolar) pattern of growth
Granular cytoplasm is distinctive, PAS positive