Chapter 26: Soft Tissue

Question 1

Sarcomas with complex karyotypes which are pleomorphic and geneticaly heterogenous and carry a poor prognosis are most often seen in whom?

Answer 1

Adults

Question 2

A well-encapsulated mass of mature adipocytes that is soft, mobile, and painless arising most commonly in adults is known as what?

Answer 2

Lipoma

Question 3

Liposarcoma most often arises in whom and in which locations?

Answer 3

• Common malignant ST tumor, adults (50-60 y/o)
• Arise in deep ST of prox. extremities and retroperitoneum

Question 4

Which genetic abberations is associated with the myxoid type of liposarcomas?

Answer 4

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

Question 5

Which genetic abberation is associated with the well-differentiated type of liposarcoma?

Answer 5

12q13-q15 –> 12q encodes MDM2 a potent inhibitor of p53

Question 6

What is the morphology of the well-differentiated type of liposarcoma?

Answer 6

Contains adipocytes with scattered atypical spindle cells

Question 7

What is the morphology of the myxoid type of liposarcoma?

Answer 7

Basophilic myxoid matrix, arborizing capillaries (“chicken-wire”) + primitive cells at various stages of adipocyte differentiation

Question 8

Which age group is the myxoid type of liposarcoma most common in and where in the body do they arise?

Answer 8

30 y/o arising in the thigh and leg

Question 9

Which translocation is associated with nodular fasciitis?

Answer 9

t(17;22) –> MYH9-USP6 fusion gene

Question 10

A history of what is seen in some cases of nodular fasciitis?

Answer 10

Trauma

Question 11

Whom does nodular fasciitis arise in and in which locations; describe its typical presentation.

Answer 11

• Appear in UE’s (arms, forearm) of young adults (20-30 yo)
• Grow rapidly over several weeks or months; typically no larger than 5cm

Question 12

What is the prognosis and tx of nodular fasciitis?

Answer 12

Often spontaneously regress and if excised, rarely recurs

Question 13

What occurs in the palmar (dupuytren contracture) subtype of superficial fibromatosis?

Answer 13

• Irregular or nodular thickening of the palmar fascia; unilateral or bilaterally
• Slow progression to flexion contracture, mainly affecting 4th and 5th fingers of hand

Question 14

Which fibrous soft tissue tumors are large, infiltrative masses that frequently recur, but do not metastasize?

Answer 14

Deep Fibromatosis (Desmoid Tumors)

Question 15

Patients with what germline mutation and syndrome are predisposed to developing deep fibromatosis (desmoid tumors)?

Answer 15

APC mutations –> familial adenomatous polyposis (FAP) - Gardner syndrome

Question 16

Which age group and sex most often develop Deep Fibromatosis (desmoid tumors); where do they arise?

Answer 16

• Women in teens to 30’s
• Arise in anterior abdominal wall but may also be seen in limb girdles or the mesentery

Question 17

Mutations in which 2 genes are associated with Deep Fibromatosis (desmoid tumors)?

Answer 17

APC or β-catenin —> ↑ Wnt signaling

Question 18

What is the characteristic histologic pattern of Deep Fibromatosis (Desmoid Tumors)?

Answer 18

Cytologically bland fibroblasts arranged in broad sweeping fascicles amid dense collagen; histology resembles scar

Question 19

What is the clinical course of Deep Fibromatosis (Desmoid Tumors) and how are they dealt with?

Answer 19

• May be disfiguring and disabling; may be painful
• Because of extensive infiltration, may be difficult to resect

Question 20

What are the most common soft tissue sarcomas of childhood and adolescence?

Answer 20

Embryonal and alveolar type of rhabdomyosarcoma

Question 21

Where do the pediatric forms of rhabdomyosarcomas most often arise?

Answer 21

Siuses, head and neck, and GU tract

Question 22

Which genetic aberrations and translocations are associated with alveolar rhabdomyosarcomas?

Answer 22

Fusion of FOXO1 with either PAX3 = (2;13) or PAX7 = (1;13)

Question 23

What is the morphology of alveolar rhabdomyosarcomas?

Answer 23

• Networks of fibrous septae dividing cells into clusters and aggregates; centers are dischohesive
• Resemblance to pulmonary alveoli
• Cross striations are not a common feature

Question 24

In sarcoma botryoides, where the tumor cells abut the mucosa of an organ, they form a submucosal zone of hypercellularity called what?

Answer 24

Cambium layer

Question 25

Where does embryonal rhabdomyosarcoma most often arise, characteristic morphology, and age group?

Answer 25

• Arise in genitourinary tract
• Patients 1-5 y/o
• Primitive spindle cells, “strap cells“

Question 26

What is tx for rhabdomyosarcoma; which variant has the best and which has the worst prognosis?

Answer 26

• Tx is surgery + chemotherapy, with or without radiation
• Botryoid variant = best prognosis
• Pleomorphic variant = worse prognosis

Question 27

Phenotype of multiple cutaneos leiomuomas may be transmitted as an autosomal dominant trait associated with what?

Answer 27

Uterine leiomyomas + renal cell carcinoma –> hereditary leiomyomatosis and renal cell cancer syndorme

Question 28

Hereditary leiomyomatosis and renal cell cancer syndorme is due to what mutation and loss of what?

Answer 28

Germline loss-of-function mutation in fumarate hydratase gene on 1q42.3

Question 29

Soft tissue leiomyomas are usually 1-2 cm and are composed of what?

Answer 29

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

Question 30

Leiomyosarcomas most often develop in which age group, sex, and structures; common presentation?

Answer 30

• Present as painless firm masses, most often in women who are 40-60 y/o
• Arise in deep ST’s of the extremities and retroperitoneum

Question 31

Morphology of Leiomyosarcomas?

Answer 31

Pleomorphic eosinophilic spindle cells w/ blunt-ended, hyperchromatic nuclei arranged in interweaving fascicles

Question 32

Leiomyosarcomas arising where are particularly deadly?

Answer 32

Those arising from great vessels, especially the IVC

Question 33

Leiomyosarcomas will stain positive for what?

Answer 33

Antibodies to smooth muscle actin and desmin

Question 34

How does Synovial Sarcoma typically present and in which age group?

Answer 34

Pt’s in their 20s-40s presenting with deep-seated mass in thigh, leg, chest wall or head and neck that has been present for several years

Question 35

Which characteristic chromosomal translocation is associated with Synovial Sarcomas?

Answer 35

t(x;18) producing SS18-SSX1, -SSX2, or -SSX4

Question 36

Synovial sarcomas, especially the biphasic type can be differentiated from other sarcoma by (+) immunohistochemical staining for what?

Answer 36

Epithelial markers (i.e., keratin)

Question 37

Characteristic morphology of Synovial Sarcoma and how do the monophasic vs. biphasic types differ?

Answer 37

• Tight fascicles of uniform basophilic spindle cells
• Biphasic type also contains gland-like structures

Question 38

What is the prognosis of Synovial Sarcomas and where do they metastasize?

Answer 38

• 5-year of 25% to 62% related to stage** and **patient age
• Commonly metz to lung and regional LN’s