Chapter 26: Soft Tissue

Question 1

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

Answer 1

Lipoma

Question 2

Liposarcoma most often arises in whom and in which locations?

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

Contains adipocytes with scattered atypical spindle cells

Question 6

What is the morphology of the myxoid type of liposarcoma?

Answer 6

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

Question 7

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

Answer 7

30 y/o arising in the thigh and leg

Question 8

Which translocation is associated with nodular fasciitis?

Answer 8

t(17;22) –> MYH9-USP6 fusion gene

Question 9

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

Answer 9

Trauma

Question 10

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

Answer 10

• 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 11

What is the prognosis and tx of nodular fasciitis?

Answer 11

Often spontaneously regress and if excised, rarely recurs

Question 12

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

Answer 12

• 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 13

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

Answer 13

Deep Fibromatosis (Desmoid Tumors)

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

APC or β-catenin —> ↑ Wnt signaling

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

Embryonal and alveolar type of rhabdomyosarcoma

Question 20

Where do the pediatric forms of rhabdomyosarcomas most often arise?

Answer 20

Siuses, head and neck, and GU tract

Question 21

Which genetic aberrations and translocations are associated with alveolar rhabdomyosarcomas?

Answer 21

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

Question 22

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

Answer 22

Cambium layer

Question 23

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

Answer 23

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

Question 24

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

Answer 24

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

Question 25

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

Answer 25

**Uterine leiomyomas** + **renal cell carcinoma** --\> **hereditary leiomyomatosis** and **renal cell cancer syndorme**

Question 26

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

Answer 26

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

Question 27

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

Answer 27

**Fascicles** of _densely_ **eosinophilic** spindle cells that tend to _intersect_ each other at **right angles**

Question 28

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

Answer 28

- 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 29

Morphology of Leiomyosarcomas?

Answer 29

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

Question 30

Leiomyosarcomas arising where are particularly deadly?

Answer 30

Those arising from **great vessels**, especially the **IVC**

Question 31

Leiomyosarcomas will stain positive for what?

Answer 31

**Antibodies** to **smooth muscle actin** and **desmin**

Question 32

Which characteristic chromosomal translocation is associated with Synovial Sarcomas?

Answer 32

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

Question 33

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

Answer 33

**Epithelial markers** (i.e., **keratin**)

Question 34

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

Answer 34

- **5-year** of **25%** to **62%** related to **_stage**_ and _**patient age_** - Commonly metz to **lung** and **regional LN's**