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151 Cards in this Set

  • Front
  • Back
Two main grading systems for soft tissue sarcomas:
1. French Sarcoma Group
- favored system
- based on differentiation, mitotic activity, and necrosis
2. NCI
The most common primary soft tissue malignancy is ___
Adipocytic tumor occur most often in adults, with two exceptions __ and ___
1. lipoblastoma
2. some lipomas
Lipoblast are not specific for malignancy, they can be seen in ___
1. pleomorphic lipomas
2. chondroid lipomas
3. lipoblastoma
4. spindle cell lipoma (less often)
lipomas are mutiple in __% of patients
intramuscular versus intermuscular lipomas
Intramuscular lipomas:
- in skeletal muscle in a variety of locations
- incomplete excision : 20% recur
Intermuscular lipoma:
- most commonly anterior abdomen

Both: mid to late adulthood
Fatty infiltration of the subsynovial connective tissue
lipoma aborescens (villous lipomatous proliferation of synovial membrane)
or (synovial lipoma)
- may be a reactive process
Lipoma variant include:
The edge/margin of a intramuscular lipomas is
well-demarcated or more often infiltrative with adipocytes surrounding atrophic muscle fibers
The subtype of lipomas is not clinically significant except for:
infiltrating intramuscular lipomas

- higher local recurrence rate
- requires resection of the entire involved muscle or compartment
diffuse overgrowth of mature adipose tissue is known as __. Subtypes include:

1. diffuse lipomatosis
- pt usually < 2yo
- +/- macrodactyly
- involves large portions of body or limbs

2. pelvic lipomatosis
- most common in black males
- constipation, urinary freq, perineal pain, back pain
3. symmetric lipomatosis
- middle aged men of Mediterranean origin
- a/w liver disease and alcohol use
- deposition of at in upper body (mostly neck)

4. steroid lipomatosis
- exogenous or endogenous steroid
- deposition of fat in face, sternal area, upper mid back (buffalo hump)
Histologically, the fat seen in lipomatosis is __
normal-appearing mature fat

- the only abnormalities are the site of involvement and the distribution of the fat
Lipomatosis of nerve: the __ is infiltrated by __ and __.

(contrast to diffuse lipomatosis)

1. epineurium
2. fibrous and adipose tissue

AKA: neural fibrolipoma, fibrolipomatous hamartoma, perineural fibroma
neural fibrolipoma: usually first recognized at _ or in __
birth or early childhood
neural fibrolipoma: is a hamartoma of the nerve sheath because the __
constituent tissues are normal components of the epineurium
In some cases of neural fibrolipoma, there is associated __
macrodactyly due to lipohypertrophy (25% cases)

- enlargement of soft tissue and bone

effects the digits of the affected nerve
neural fibrolipoma: most commonly effects __
median nerve, followed by ulnar nerve
neural fibrolipoma: is typically a __ event
- not associated with any syndrome or known hereditary predisposition
neural fibrolipoma: histologically
- fatty infiltration w/ admixed fibrous tissue into the epinerual and perineural tissue

- concentric perineural fibrosis (about individual nerve bundles)
neural fibrolipoma: onset is in ___, but presentation to the physician is usually in __
- early childhood/birth

- early adulthood
superficial lipomas > 10 cm often turn out to be __
Atypical lipomatous tumors
dermal lipoma versus nevus lipomatosus superficialis
dermal lipoma:
- common, solitary lesion
- most likely a fibroepithelial polyp in which the adipose tissue predominates

nevus lipomatosus superficialis
- used ONLY when such lesions are mutliple and clustered about the lower limb girdle
- considered a hamartoma
intramuscular lipomas present in __ as __
mid adulthood

slow growing, deep-seated mass in the thigh or trunk
intramuscular lipoma versus intramuscular hemangioma (angioma)
intramuscular lipoma:
- mid-adulthood
- vessels are scarce and capillary-sized
- less frequent recurrences (20% w/ incomplete excision)

intramuscular angioma:
- younger(adolescent - young adult)
- prominent vascular component
- high probability of recurrence with incomplete excision (30-50%)
- slow growing, often PAINFUL, especially after exercise

Note: angioma: because most are a mix of capillary, small artery, venous, and lymphatic-like spaces
__% of intramuscular lipomas are well-circumscribed and non-infiltrative; these __ recur

do not recur
diagnosis of intermuscular lipomas requires __ and/or__
radiologic and/or intraoperative findings
Multiple symmetric lipomatosis is the __ common type of lipomatosis. It mainly involves the ____. It is associated with ___
- type of diffuse lipomatosis
- most common type of lipomatosis
- neck and shoulder areas
- a/w peripheral neuropathy, alcoholism, and hyperlipidemia
Liopmatosis mainly effects __
adult men
(except diffuse lipomatosis: <2 yo)
Lipoblastoma (aka__) is most commonly seen in the __ years of life
infantile lipoma

first 3 years of life
lipoblastoma most commonly occur in the _

- other sites: mediastinum, trunk, retroperitoneum, head&neck, within various organs (lung, heart, parotid gland)
Lipoblastoma versus lipoblastomatosis
- superficial (limited to subcutis)

- infiltrates deep muscle
Lipoblastoma histologically
- lobulated admix of mature and immature adipocytes
- lipoblasts in various stages of development
- number of lipoblasts varies with age
lipoblastomas can have myxoid stroma and a plexiform vascular pattern, mimicking a __
myxoid liposarcoma

- myxoid liposarc is rare <10yo
- expect to see nuclear atypia
- LACK the pronounced lobulated appearance of lipoblastoma
lipoblastoma: characteristic cytogenetic finding
rearrangements involving 8q11-13 (majority of cases)
lipoblastomas are __ lesions

- no mets
- no malignant transformation
- uncommonly recur (except: lipoblastomatosis has a greater chance of recurrence 9-22%) requiring wide local excision
lipoblastomas occur mostly in _
male children < 3yo
Histologic features of lipoblastoma
- lobules of mixed mature and immature adipocytes separated by fibrous septae
- more immature lobules contain primitive mesenchymal cells, lipoblasts, and small capillaries, all in a myxoid background (WITHOUT ATYPIA to distinguish it from a myxoid liposarc)
- more mature lobules resemble lipoma with a little more prominent nuclei and variation in adipocyte size
- commonly see foci of EMH
- may see hibernoma-like foci
lipoblastoma can appear very similar to a myxoid liposarcoma
- mxyoid liposarc in pts 10-30 are typically low grade tumors!
- lipoblastomas are lobulated, have more degress of maturation, lack nuclear atypia
- rarely lipoblastomas occur in older children
- cytogenetics may be needed
- t(12;16) myxoid liposarc
- rearrangements involving 8q11-13 (PRAG1 gene) in lipoblastoma
angiolipomas are usually <__cm
angiolipomas consists of two mesenchymal components:
1. mature adipocytes
2. branching capillary-sized vessels, with fibrin thrombi
cellular angiolipomas are those composed of __
predominantly vascular component

DDX: angiosarcoma or Kaposi sarcoma
angiolipomas have a __ karyotype
Myolipomas consists of two mesenchymal components:
1. mature adipocytes
2. smooth muscle
Myolipoma (aka___) are extremely__
1. extrauterine lipoleiomyoma
2. rare
most myolipomas (extrauterine lipoleiomyomas) occur __
- deep
- abdominal cavity, retroperitoneum, inguinal areas
average size for a myolipoma is ___
15 cm (big tumors)

Note: smaller lesions are seen in the subcutis
in myolipomas, the __ component usually dominates
smooth muscle component predominates (muscle:fat ratio 2:1)
myolipomas: histological findings
- evenly distributed short fascicles of smooth muscle intermixed with fat (sieve-like pattern)
- NO mitoses
- NO atypia in the lipomatous component!!!
- NO floret cells or lipoblasts
- NO large-caliber thick-walled vessels (AML)

- angiomyolipoma
- WD liposarcoma with heterologous smooth muscle differentiation!!!
chondroid lipoma: DDX
1. chondroid lipoma
2. myxoid liposarcoma
3. extraskeletal chondrosarcoma
chondroid lipoma most commonly occur
mostly proximal extremity/ limb gridles
chondroid lipoma are often __-seated tumors, involving __
deep-seated tumors

involving skeletal muscle and deep fibrous connective tissues
chondroid lipoma often present as __, however, in 50% of cases, there is a history of __
painless mass of variable duration

recent history of enlargement
chondroid lipoma: histologic findings
- hallmark: nests and chords of abundant uni- and multi-vaculated lipoblasts embedded in a prominent myxoid to hyalinized chondroid matrix admixed with variable amounts of mature adipose
Key findings allowing recognition of a chondroid lipoma
- admixture of mature adipocytes, lipoblasts with bland nuclei, and hibernoma-like cells
The Frech Sarcoma Group system gaining favor for gradin STS because of __
- greater reproducibility
- less patients assigned to intermediate category
Single most common type of primary soft tissue malignancy __
Liposarcaroma (including the atypical lipomatous tumor)
Majority of adipocytic tumors occur in __hood, except for ___ and ___

1. lipoblastoma
2. occasional lipomas
Do lipoblasts = malignancy?

1. Lipoblasts are not seen in every liposaroma:
- some WD liposarcoma/Atypical lipomatous tumors
- some myxoid liposaromas

2. Lipoblasts can be seen in some benign tumors
- pleomorphic lipomas
- less often spindle cell lipomas
- chondroid lipomas
- lipoblastoma
Lipomas usually occur in the __ and ___, rarely do they occur in the __ and __
trunk/ proximal extremity

hands/ feet
Lipomas are usually solitary, but __% of patients have multiple lesions
Rate of recurrence of lipomas should be less than __
Grossly, most lipomas are ___, thinly ____, and ___

Rarely are the >__cm, if so:
thinly encapsulated

rarely >10cm, if so: should be sample carefully, often turn out to be a atypical lipomatous tumor/ED liposarcoma
Lipomas are composed of ___ adipocytes, with minimal variation in ___, and nuclei that are __
- univacuolated
- cell size
- inconspicuous, small compressed to the edge of the cell
Foci of adipocytic cells with variable cell size, in an otherwise benign lipoma, may represent __
- microscopic fat necrosis
reproducible karyotypic abnormalities involving ___ are seen in subcutaneous lipomas
Dermal lipoma, is a common, ___ skin lesion, mainly in ___ (age group), and most likely represents a __.
- common, pedunculated skin lesion
- young adults
- fibroepithelial polyp (skin tag) with a prominent adipose tissue component
- hamartomatous lesion
If a patient presents with multiple, grouped dermal lipomas, clustered around the ___, the term __ should be used.
- lower limb girdle
- nevus lipomatosus superficialis
Synovial lipomas (aka___) is characterized by ___ collections of __ adipocytes which project, in a ___ fasion, into the joint space. The overlying synovium is often __ and variably __
- lipoma aborescens
- subsynovial collections of mature adipocytes
- villous fashion

- hyperplastic synovium
- variably inflamed
Synovial lipoma usually occurs in ___ (age group), most often affects the ___, and is usually associated with ___
- adults
- knee
- degenerative joint disease
Synovial lipoma is most likely a __ process
Intramuscular lipomas differ from usual superificial lipomas
- poorly circumscribed
- infiltrative
- up to 20% (versus <1-2%) chance of recurrence if incompletely excised

Note: 10% of intramuscular lipomas are circumscribed, non-infiltrative, and tend NOT to recur
Intramuscular lipomas can and should be differentiated from intramuscular ___
intramuscular angioma(hemangiomas)!!

Intramuscular lipomas:
- scarce blood vessels
- vessels that are present are usually capillary-sized

Intramuscular angioma:
- variable amounts of mature fat
- more vascular lesions, classified by vessel size: small (capillary, large (cavernous), and most commonly mixed types

Intramuscular lipomas are less likely to recur, compared to intramuscular angiomas (up to 20% versus 30-50%)
Note: a WD liposarcoma/atypical lipomatous tumor is __ common than an intramuscular lipoma
more common
Intermuscular lipomas usually occur in the __
anterior abdnominal wall
Lipomatosis is a __ condition characterized by diffuse ___ of __ tissue. It usually affects __
- rare
- overgrowth
- fatty tissue
- adult males
There are four principle forms of lipomatosis
1. multiple symmetric lipomatosis
2. asymmetric lipomatosis
3. pelvic lipomatosis
4. mediastinoabdominal lipomatosis
Multiple symmetric lipomatosis is the __ form. It affects mainly the ___ and ___ region. Often associated with __, ___, and ___. Similary clinical features have been described in patients with a history of ___ therapy
- most common form
- neck and shoulder regions
- peripheral neuropathy, alcoholism, and hyperlipidemia

- HIV-1 protease inhibitor
Asymmetric lipomatosis is __ disributed.
- no associated with a clinical syndrome
Pelvic lipomatosis develops around the __ and __
rectum and bladder
- associated symptoms (obstruction and uremia)
- characteristic radiology
mediastinoabdominal lipomatosis and ___ lipomatosis are both associated with ___
type II diabetes
The adipose tissue in lipomatosis is __
- mature
- poorly circumscribed
- +/- focal fibrosis
Lipoblastoma is preominantly a tumor of __ (age group) that affects mostly __
- infancy (<3 yo)
- males

- some cases seen up to 7-8 yo
lipoblastomas present as __, __, ___-growing mass in a __
superficial, circumscribed, slow-growing, mass in a limb of a boy < 3 yo
lipoblastomas that present as deep-seated, larger, infiltrative lesions are termed __
lipoblastomatosis (diffuse form)
Lipoblastomas __ recur
typcially do NOT recur, if they do, it is usually with an infiltrative tumor (lipoblastomatosis)
Lipoblastomas histologically are characterized by __
- lobular architecture
- lobules composed of mature and immature adipocytes in VARYING degress of maturation
- lobules separated by fibrous septae
- IMMATURE LOBULES: consists of myxoid stroma with primitive mesenchymal cells, lipoblasts, and small capillaries (resembling myxoid liposarcoma BUT without atypia)
- MATURE LOBULES: resemble lipoma but with some variation in cell size and more prominent nuclei

- commonly may see foci of hibernoma-like cells and foci of extramedullary hematopoiesis
Key features allowing differentiation of the immature lobules of a lipoblastoma from myxoid liposaroma are __
- lobular architecture
- lack of nuclear atypia
- greaters spectrum of maturation
If a lipoblastoma recurs, it often shows ___ toward a __
- maturation
- simple lipoma
Lipoblastoma show consistent chromosomal abnormalities involving __
8q11-13 PLAG1 gene
Myxoid liposaromas are __ in children <__ years old; however those occuring in the ___ age group tend to be __ grade tumors
- exceedling rare
- 10 yo

- myxoid liposarcomas occuring in the 10-20 yo age group tend to be very low grade tumors!!
Angiolipomas, unlike typical lipomas, are often __
- mulitple (>50% cases)
- 50% painful or tender
Angiolipomas most often occur __
- in males-
- early adulthood
- wide anatomic distribution, but most often upper limb (forearm) and trunk
Most angiolipomas are <__cm
<2cm (small)
Angiolipomas __ recur, but __
- do NOT recur
- BUT new lesions may continue to develop
A key diagnostic feature of angiolipomas
- small fibrin thrombi
- their absence argues STRONGLY agianst the diagnosis
Angiolipomas with 90% or more vascularity are termed __
cellular angiolipomas
- can have a spindled endothelial cell appearance
- prominent pericapillary pericytes

- resemble KS or primitive capillary hemangioma
Angiolipomas can be distinguished from Kaposi sarcoma and primitive capillary hemangioma by __
- presence of intralesional mature adipocytes
- presence of microthrombi
Longstanding angiolipomas can show degenerative features
- perivascular fibrosis and hyalinization
- stromal myxoid change
Angiolipomas consistently have a __ karyotype
normal (unlike other fatty tumors)
myolipoma is __. They usually occur in __ or __, and present as __
- rare
- abdomen or pelvis
- large tumors
- slightly more common in females
DDX of a myolipoma (leiomyolipoma) includes ___ and ___
1. angiomyolipoma
2. WD liposaroma with heterologous smooth muscle component
In a chondroid lipoma, the cytoplasm is finely ___, containing small __ droplets or ___-positive ___. Alternatively, the cytoplasm may be __
- vacuolated
- lipid
- PAS+ glycogen

- eosinophilic and granular
Chondroid lipomas are highly ____tumors and common have foci of ___ and ___
- vasular
- hemorrhage and fibrosis
IHC in a chondroid lipoma
- lipoblast are WEAKLY S-100+ (increaseing + as they mature)

- vimentin+
- EMA-
- Ki-67 <1%
Spindle cell lipomas are __ in the lower extremity
distinctly RARE!!
spindle cell/pleomorphic lipoma usually occur in __
- older men (>55 yo)
- 90% are men (only 10% women)
spindle cell lipoma histologically consists of ___
- bland mitotically inactive spindle cells in parallel short fascicles between fat cells
- spindle cells are short, undifferentiated cells with poorly defined cytoplasm
- thick, ropey collagen bundles
- many mast cells
- +/- lymphs and plasma cells
+/- myxoid stroma
pleomorphic lipoma histologically consists of __
- similar to spindle cell lipoma PLUS:
- small spindled and round hyperchromatic cells
- multinucleated giant cells with radially arranged nuclei (floret cells)
IHC in spindle cell/pleomorphic lipomas
-spindle cells are CD34+ and RARELY S-100+
A few spindle cell/pleomorphic lipomas are entirely intradermal and are more common in __
A lesion that looks like a spindle cell/pleomorphic lipoma, but occuring in deep tissue is better diagnosed as a ___
atypical lipomatous tumor
- often supported by cytogenetics

- also any lesion in an unusal site should be suspect
The spindle cell predominant spindle cell lipoma may show ___ , reminiscent of a schwannoma
- nuclear palisading

Distnguished from a schwannoma by :
- intralesion adipocytes
- spindle cells are S-100-
Floret cells in pleomorphic lipomas exhibit a __ of nuclei and __ cytplasm
- ring of nuclei
- eosinophilic cytoplasm
spindle cell/pleomorphic lipomas may contain __
Distinction between a pleomorphic lipoma and a WD liposarcoma rest mainly on:
- location (anatomic site and superifical nature)
- lack of marked variation in adipocyte size
- minimal atypia in the adipocyte nuclei

- spindle cell lipomas - abnormalities of 13q and 16q
- WD liposarcoma - giant marker and ring chromosome (12q)
hibernoma is a __ neoplasm consisting of at least in part __
- rare
- brown fat cells with granular, multivacuolated cytpolasm admixed with variable amounts of white fat
Residual brown fat (not hibernoma) is common found in the __ and __
cerivcal and axiallary regions around lymph nodes
Hibernomas usually present in __
- yound adults
Most common site for a hibernoma
- thigh
- followed by trunk, upper extr, H&N

- <10% occur intrabdominally or intrathoracically
Spindle cell and myxoid variants of hibernoma tend to occur in the ___
posterior neck/shoulder region similar to spindle cell/pleomorphic lipomas
There are six variants of hibernoma based on __
- stromal background
1. granular or eosinophilic
2. mixed variant with pale and esoinophiic cells
3. lipoma-like variant (small foci of white fat and multivacuolated lipoblast-like cells)
4. myxoid variant
5. spindle cell variant (thick collagen bundles, scattered mast cells, mature adipose)
6. pale variant (pure pale cells)
Hibernoma cells have a __ placed nucleus
In the spindle cell variant of hibernoma, the spindle cells are CD__+
CD34+ (similar to those of spindle cell lipomas)
IHC in hibernomas
- S-100+
Hibernomas are grossly well-___ and ___. Average size is ___. Majority are located in the ___, with __% being ___, most often in the __
- well-circumscribed and encapsulated
- 5-10 cm
- subcutaneous tissues
- 10% being intramuscular, most often in the thigh
DDx of hibernoma: remember that a myxoid liposarcoma may contain __
hibernoma-like cells
Atypical lipomatous tumor (ALT)/WD liposarcoma are considered ___ (behavior)
intermediate (locally aggressive) malignant mesenchymal neoplasms
ALT/WD lipsarcoma show at least in part significant ___ and at least focal ___
- variation in cell size
- nuclear atypia in BOTH the adipocytic and stromal cells
How often do ALT/WD liposarcoma metastasis?
- they do not show metastatic potential UNLESS they dedifferentiate
ALT/WD liopsarcoma account for __% of liposarcomas
40-45%!! Most common type!
ALT/WD lipsarcoma most often present in ___
- middle aged adults (peak in 50's)
- M=F (except for spermatic cord lesions! ;) )
ALT/WD liopsarcoma: most common sites
- usually deep-seated in limbs (especially thigh)
- retroperitoneum
- paratesticular
- mediastinum
- subcutaneous tissues
- RARELY in the skin
Grossly, ALT/WD liposarcoma__
- usually well-circumscribed, lobulated
- IN RETROPERITONEUM may be multiple discontinuous masses
- rarely infiltrative pattern
4 main subtypes of ALT/WD liposarcoma
1. adipocytic (lipoma-like) MOST COMMON
2. sclerosing SECOND MOST COMMON (most often retroperitoneal or paratesticular)
3. spindle cell
4. inflammatory (RARE, retroperitoneum)

Mixed type is common, especially in retroperitoneum
DDX of inflammatory WD liposarcoma
1. inflammatory myofibroblastic tumor
2. Hodgkin lymphoma
3. Castleman disease
4. NHL

presence of an adipocytic component (which may be scarce) or the presence of bizarre multinucleate stromal cells is a clue
Heterologous differentiation in a WD liposarcoma?
Yes! although rare!

- smooth or skeletal muscle differentiation
- metaplastic bone formation

MUST distinguish heterologous differentiation in a WD liposarcoma from that arising in a dedifferentiated liposarcoma

HMB45- (if AML in DDX)
cytogenetic abnormality of ALT/WD liposarcoma
- supernumerary circular (ring) and giant rod chromosomes
-- contain amplification of 12q region incluidng MDM2 gene
Risk of dedifferentiation of ALT/WDLPS is based larged on __
site and lesional duration
- probably >20% for retroperitoneal
- <2% in limbs
Dedifferentiated liposarc show __, either in the primary or recurrent tumor, from ___ to ___
- transition
- ALT/WDLPS to NON-LIPOGENIC sarcoma of variable histologic grade
Most (about __%) of dedifferentiated liposarc arise __, while __% occur in __
- 90%
- de novo
- 10% occur in recurrences
Occurence of dedifferentiated liposarc is most common in the __ and rare in the __
- most common in retroperitoneum, spermatic cord

- rare in subcutaneous tissues
Clue to dediff in a limb lesion is __
history of recent increase in size of a long standing mass
Histologic hallmark of dediff liposarc
- seeing the transition from ALT/WDLPS to any type of non-lipogenic sarcoma (most often high grade)
- the areas of dediff are most often recognizable grossly!!!
Significance of microscopic foci of dedifferentiation in a liposarocoma
- uncertain!!
- usually the areas of dedifferentiation are grossly recognizable

- note: dediff can be more gradual and low grade (uncommon)
Most common histologic appearance of dediff liposarc
- unclassifiable MFH-like pleomorphic sarcoma
- intermediate to high grade myxofibrosarcoma
Dediff liposarc appears to be clinically __ aggressive compared to other high grade pleomorphic sarcomas
less aggressive

- careful sampling, looking for the WD liposarc component is important
The local recurrence of a dediff liposarcoma may be entirely __
well differentiated
Dediff liposarcoma cytogenetic findings
- similar to ALT/WDLPS, ring or giant marker chromosomes
- still limited number of cases examined to determine if a consistent difference between the two exists
Dediff liposarc: tendency to recur locally is __% and distant metastases in ___%
- 40% recur locally; almost all retroperitoneal tumors recur if followed 10-20 years

- 15-20% distant metastasis

- overall mortality about 30% over 5 years
How useful is the extent of dedifferentiated areas at predicting the outcome?
It is NOT!
5% of dediff liposarcomas can show foci of __ differentiation
- heterologous
- most commonly myogenic (smooth muscle or rhabdomyosarcomatous)