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Soft Tissue Tumors - Flashcard Topics with MCQs
TOPIC 1: General Overview & Epidemiology
Key Points:
- Soft tissue = non-epithelial tissue excluding skeleton, joints, CNS, hematopoietic/lymphoid tissues
- Benign : malignant ratio = ~100:1
- ~12,000 sarcomas/year in the U.S. (~1% of all cancers)
- Most sarcomas arise in extremities (especially thigh)
- ~15% occur in children; incidence increases with age
Theory MCQ 1
The ratio of benign soft tissue tumors to malignant sarcomas is approximately:
- A) 10:1
- B) 50:1
- C) 100:1
- D) 1000:1
Answer: C) 100:1
Benign tumors greatly outnumber sarcomas at roughly 100:1.
Theory MCQ 2
Soft tissue sarcomas account for what percentage of all cancer deaths in the U.S.?
- A) Less than 1%
- B) ~2%
- C) ~5%
- D) ~10%
Answer: B) ~2%
Despite representing ~1% of cancers, sarcomas cause ~2% of cancer deaths due to their aggressive behavior.
Clinical MCQ 1
A 55-year-old man presents with a painless, enlarging deep thigh mass. Biopsy confirms a soft tissue sarcoma. Which anatomical site is the MOST common location for soft tissue sarcomas?
- A) Retroperitoneum
- B) Head and neck
- C) Extremities (especially thigh)
- D) Trunk
Answer: C) Extremities (especially thigh)
The thigh is the most common primary site for soft tissue sarcomas in adults.
TOPIC 2: Pathogenesis & Molecular Classification
Key Points:
- Most sarcomas are sporadic
- Germline associations: NF1, Gardner syndrome, Li-Fraumeni, Osler-Weber-Rendu
- Environmental factors: radiation, burns, toxins
- Cell of origin: pluripotent mesenchymal stem cells
- Simple karyotype (15-20%): Ewing sarcoma, synovial sarcoma - fusion proteins, therapy targets
- Complex karyotype (80-85%): leiomyosarcoma, UPS - genomic instability
Theory MCQ 3
Which of the following sarcomas is characterized by a SIMPLE karyotype with a tumor-specific fusion protein?
- A) Leiomyosarcoma
- B) Undifferentiated pleomorphic sarcoma
- C) Synovial sarcoma
- D) Pleomorphic liposarcoma
Answer: C) Synovial sarcoma
Synovial sarcoma has a simple karyotype and harbors the SS18-SSX fusion gene via t(X;18). Leiomyosarcoma and UPS have complex karyotypes.
Theory MCQ 4
Li-Fraumeni syndrome predisposes to soft tissue sarcomas due to germline mutation in which gene?
- A) NF1
- B) APC
- C) TP53
- D) CTNNB1
Answer: C) TP53
Li-Fraumeni syndrome is caused by germline TP53 mutations, predisposing to multiple malignancies including soft tissue sarcomas.
Clinical MCQ 2
A 12-year-old girl is found to have multiple café-au-lait spots, axillary freckling, and develops a soft tissue sarcoma. The germline mutation most likely responsible is in:
- A) APC gene
- B) NF1 gene
- C) TP53 gene
- D) CTNNB1 gene
Answer: B) NF1 gene
Neurofibromatosis type 1 (NF1 mutation) presents with café-au-lait spots, freckling, and is associated with soft tissue sarcoma development.
TOPIC 3: Tumors of Adipose Tissue - Lipoma
Key Points:
- Most common soft tissue tumor in adults
- Arises in subcutis of proximal extremities and trunk
- Middle adulthood
- Cured by simple excision
Theory MCQ 5
What is the most common soft tissue tumor in adults?
- A) Liposarcoma
- B) Lipoma
- C) Nodular fasciitis
- D) Desmoid tumor
Answer: B) Lipoma
Lipoma is the most common soft tissue tumor in adults, arising most often in the subcutis of proximal extremities and trunk.
Clinical MCQ 3
A 45-year-old woman presents with a soft, mobile, painless 3 cm subcutaneous mass over her upper arm for 2 years. It has not changed in size. What is the most appropriate management?
- A) Wide local excision with radiation
- B) Simple excision - curative
- C) Observation only, no treatment needed unless symptomatic
- D) Core needle biopsy followed by chemotherapy
Answer: B or C (Both are correct depending on context; the key teaching point: simple excision is curative)
Lipomas are benign and cured by simple excision. Observation is also acceptable if asymptomatic and typical features are present.
TOPIC 4: Liposarcoma
Key Points:
- Most common sarcoma in adults (deep soft tissues & retroperitoneum, ages 50-60)
- Three subtypes:
- Well-differentiated: MDM2 amplification (chr 12q13-15); MDM2 inhibits p53; indolent
- Myxoid: t(12;16); basophilic matrix + arborizing capillaries; intermediate malignancy
- Pleomorphic: lipoblasts + bizarre nuclei; complex karyotype; most aggressive
Theory MCQ 6
Well-differentiated liposarcoma is characterized by amplification of which chromosome region, leading to overexpression of MDM2?
- A) 12q13-q15
- B) 11q13
- C) 17p13
- D) 22q11
Answer: A) 12q13-q15
MDM2 amplification on chromosome 12q13-q15 is the hallmark of well-differentiated liposarcoma; MDM2 inhibits p53 tumor suppressor function.
Theory MCQ 7
Myxoid liposarcoma is associated with which chromosomal translocation?
- A) t(9;22)
- B) t(12;16)
- C) t(11;22)
- D) t(X;18)
Answer: B) t(12;16)
t(12;16) arrests adipocyte differentiation and is the defining translocation of myxoid liposarcoma.
Theory MCQ 8
Which subtype of liposarcoma contains lipoblasts (immature adipocytes) with bizarre nuclei and has the worst prognosis?
- A) Well-differentiated
- B) Myxoid
- C) Round cell
- D) Pleomorphic
Answer: D) Pleomorphic
Pleomorphic liposarcoma contains sheets of anaplastic cells with bizarre nuclei and immature lipoblasts; it carries the highest metastatic risk and worst prognosis.
Clinical MCQ 4
A 58-year-old man presents with a large retroperitoneal mass. Histology shows adipocytes with atypical spindle cells; MDM2 gene amplification is confirmed on FISH. What is the diagnosis and expected behavior?
- A) Myxoid liposarcoma - intermediate malignancy
- B) Well-differentiated liposarcoma - indolent behavior
- C) Pleomorphic liposarcoma - high metastasis risk
- D) Lipoma - benign, cured by excision
Answer: B) Well-differentiated liposarcoma - indolent behavior
MDM2 amplification points to well-differentiated liposarcoma, which behaves indolently but tends to recur locally.
TOPIC 5: Nodular Fasciitis
Key Points:
- Self-limited fibroblastic/myofibroblastic proliferation
- Upper extremities, young adults
- ~25-50% have trauma history
- Rapid growth over weeks/months - MIMICS sarcoma
- t(17;22) → MYH9-USP6 fusion gene (same as aneurysmal bone cyst)
- Spontaneously regresses; malignant transformation virtually nonexistent
- Histology: plump fibroblasts in myxoid background with zonation, RBCs, mitoses
Theory MCQ 9
Nodular fasciitis contains which fusion gene, also found in aneurysmal bone cyst?
- A) SS18-SSX
- B) PAX3-FOXO1
- C) MYH9-USP6
- D) MDM2-CDK4
Answer: C) MYH9-USP6
The t(17;22) translocation creates the MYH9-USP6 fusion, shared with aneurysmal bone cyst, confirming clonal (not purely reactive) origin.
Theory MCQ 10
Which histological finding is characteristically ABSENT in nodular fasciitis?
- A) Mitotic figures
- B) Extravasated red blood cells
- C) Neutrophils
- D) Lymphocytes
Answer: C) Neutrophils
Nodular fasciitis shows abundant mitotic figures, lymphocytes, and extravasated RBCs, but neutrophils are rarely present.
Clinical MCQ 5
A 28-year-old man presents with a rapidly growing 3 cm forearm mass that appeared over 6 weeks after a minor injury. Biopsy shows plump spindle cells in a myxoid background with abundant mitoses and extravasated RBCs. The MOST likely diagnosis is:
- A) Fibrosarcoma
- B) Nodular fasciitis
- C) Synovial sarcoma
- D) Leiomyosarcoma
Answer: B) Nodular fasciitis
Rapid growth in a young adult after trauma + myxoid background + zonation + RBCs + mitoses = classic nodular fasciitis. Despite sarcoma-like histology, it is benign.
Clinical MCQ 6
The same patient's biopsy was initially read as "concerning for sarcoma" due to high mitotic activity. What is the key distinguishing feature that argues AGAINST malignancy?
- A) Presence of lymphocytes
- B) Myxoid stroma
- C) Clinical rapid growth in a young patient with trauma history + small size + spontaneous regression
- D) Extravasated red blood cells
Answer: C) Clinical context: rapid growth, young patient, trauma history, small size, tendency to self-resolve
Nodular fasciitis is the classic "pseudosarcoma." Clinical context (rapid growth after trauma in young adult, <5 cm, upper extremity) is essential to avoid overdiagnosis.
TOPIC 6: Superficial Fibromatoses
Key Points:
- Infiltrative fibroblastic proliferations; local deformity but NO metastasis
- Affects males more than females
- Histology: nodular fascicles of fibroblasts in dense collagen
- Subtypes:
- Palmar (Dupuytren contracture): nodular palmar fascia thickening, bilateral possible
- Plantar: young patients, unilateral, no contracture
- Penile (Peyronie disease): dorsolateral induration
Theory MCQ 11
Dupuytren contracture is a clinical manifestation of which type of superficial fibromatosis?
- A) Plantar fibromatosis
- B) Palmar fibromatosis
- C) Penile fibromatosis
- D) Deep fibromatosis
Answer: B) Palmar fibromatosis
Dupuytren contracture results from nodular thickening/fibrosis of the palmar fascia (palmar fibromatosis).
Clinical MCQ 7
A 50-year-old male alcoholic presents with progressive inability to extend his ring and little fingers. Examination reveals cord-like thickening of his palm. What is the most likely diagnosis?
- A) Carpal tunnel syndrome
- B) Dupuytren contracture (palmar fibromatosis)
- C) Desmoid tumor
- D) Flexor tenosynovitis
Answer: B) Dupuytren contracture (palmar fibromatosis)
Palmar fascia thickening with fixed flexion contracture of the 4th and 5th fingers in a middle-aged male = Dupuytren. Associated with alcoholism, diabetes, epilepsy.
TOPIC 7: Deep Fibromatosis (Desmoid Tumors)
Key Points:
- Large, infiltrative, frequently recur but do NOT metastasize
- Most common in teens-30s, predominantly women
- Locations: abdominal wall (most common), limb girdles, mesentery
- Mutations: CTNNB1 (β-catenin) or APC genes → increased Wnt signaling
- Gardner syndrome (FAP) = germline APC mutation → mesenteric desmoids
- Morphology: gray-white firm masses, cytologically bland fibroblasts, dense collagen
Theory MCQ 12
Desmoid tumors (deep fibromatoses) are associated with mutations in which signaling pathway?
- A) MAPK/ERK pathway
- B) Wnt/β-catenin pathway
- C) PI3K/AKT pathway
- D) JAK/STAT pathway
Answer: B) Wnt/β-catenin pathway
Mutations in CTNNB1 (β-catenin gene) or APC lead to increased Wnt signaling, driving desmoid tumor formation.
Theory MCQ 13
Which syndrome predisposes to desmoid tumors of the mesentery due to a germline APC mutation?
- A) Li-Fraumeni syndrome
- B) Neurofibromatosis type 1
- C) Gardner syndrome (FAP)
- D) Osler-Weber-Rendu syndrome
Answer: C) Gardner syndrome (FAP)
Gardner syndrome is a variant of FAP with germline APC mutations; mesenteric desmoid tumors are a hallmark extra-colonic manifestation.
Clinical MCQ 8
A 25-year-old woman who underwent colectomy for familial adenomatous polyposis (FAP) now develops a large, poorly demarcated abdominal mass. Biopsy shows bland fibroblasts in dense collagen resembling scar tissue. There are no atypical mitoses. What is the diagnosis?
- A) Well-differentiated liposarcoma
- B) Retroperitoneal leiomyosarcoma
- C) Desmoid tumor (deep fibromatosis)
- D) Gastrointestinal stromal tumor (GIST)
Answer: C) Desmoid tumor (deep fibromatosis)
Post-colectomy FAP patient + bland fibroblasts + infiltrative abdominal mass + no metastasis = mesenteric desmoid. APC mutation is the link.
TOPIC 8: Rhabdomyosarcoma
Key Points:
- Most common soft tissue sarcoma of childhood and adolescence
- Arises from mesenchymal stem cells (NOT mature muscle)
- Sites: sinuses, head/neck, genitourinary tract
- Three subtypes:
- Embryonal (60%): primitive round/spindle cells + rhabdomyoblasts; sarcoma botryoides variant (hollow viscera)
- Alveolar (20%): t(2;13) or t(1;13) → PAX3/PAX7-FOXO1 fusion; worst prognosis
- Pleomorphic (20%): adults; large eosinophilic cells; requires myogenin IHC
- Treatment: surgery + chemo ± radiation
- Best prognosis: botryoid variant; worst: pleomorphic
Theory MCQ 14
The alveolar subtype of rhabdomyosarcoma is characterized by which chromosomal translocation?
- A) t(12;16)
- B) t(X;18)
- C) t(2;13) or t(1;13)
- D) t(17;22)
Answer: C) t(2;13) or t(1;13)
t(2;13) fuses PAX3 with FOXO1; t(1;13) fuses PAX7 with FOXO1. These create chimeric transcription factors that disrupt normal muscle differentiation.
Theory MCQ 15
Sarcoma botryoides is a variant of which tumor, and in which locations does it typically arise?
- A) Alveolar rhabdomyosarcoma; extremities
- B) Embryonal rhabdomyosarcoma; hollow viscera (urinary bladder, vagina)
- C) Pleomorphic rhabdomyosarcoma; retroperitoneum
- D) Leiomyosarcoma; uterus
Answer: B) Embryonal rhabdomyosarcoma; hollow viscera (urinary bladder, vagina)
Botryoid (grape-like) sarcoma is an embryonal RMS variant arising in hollow viscera and carries the best prognosis among RMS subtypes.
Theory MCQ 16
Identification of rhabdomyosarcoma cells requires demonstration of muscle-specific proteins. Which marker is most useful in pleomorphic RMS?
- A) S-100
- B) Keratin
- C) Myogenin
- D) CD34
Answer: C) Myogenin
Myogenin (and MyoD1) are muscle-specific transcription factors used by IHC to confirm skeletal muscle differentiation in pleomorphic RMS, which otherwise resembles other pleomorphic sarcomas.
Clinical MCQ 9
A 4-year-old boy presents with a polypoid, "grape-like" mass protruding from the urethra. Histology shows sheets of primitive round cells with rhabdomyoblasts beneath an intact mucosa. What is the diagnosis?
- A) Embryonal carcinoma
- B) Nephroblastoma (Wilms tumor)
- C) Sarcoma botryoides (embryonal rhabdomyosarcoma)
- D) Alveolar rhabdomyosarcoma
Answer: C) Sarcoma botryoides (embryonal rhabdomyosarcoma)
Grape-like polypoid mass from hollow viscera (urinary tract/vagina) in a child = sarcoma botryoides, a variant of embryonal RMS. Characteristic cambium layer seen histologically.
Clinical MCQ 10
A 15-year-old male presents with a rapidly growing mass of his right cheek. Biopsy shows fibrous septa dividing uniform round cells into alveoli-like clusters with weak cohesion. FISH reveals PAX3-FOXO1 fusion. What is the expected prognosis compared to other RMS subtypes?
- A) Best prognosis - likely cured with surgery alone
- B) Intermediate prognosis - responds well to chemo
- C) Worst among RMS subtypes - aggressive, poor prognosis
- D) Same prognosis as embryonal subtype
Answer: C) Worst among RMS subtypes - aggressive, poor prognosis
Alveolar RMS with PAX3-FOXO1 fusion is the most aggressive RMS subtype with the worst prognosis.
TOPIC 9: Leiomyoma
Key Points:
- Most common in uterus; also skin, GI tract, deep soft tissues
- FH (fumarate hydratase) gene mutation in multiple cutaneous leiomyomas + renal cell carcinoma
- Morphology: intersecting fascicles of eosinophilic spindle cells, blunt-ended nuclei, minimal atypia, few mitoses
- Cured by simple excision
Theory MCQ 17
Multiple cutaneous leiomyomas associated with renal cell carcinoma are linked to mutation in which gene?
- A) CTNNB1
- B) APC
- C) Fumarate hydratase (FH)
- D) MDM2
Answer: C) Fumarate hydratase (FH)
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome is caused by germline FH mutations.
Clinical MCQ 11
A 32-year-old woman presents with menorrhagia and difficulty conceiving. Ultrasound reveals multiple uterine masses. What is the most likely diagnosis?
- A) Leiomyosarcoma
- B) Endometrial carcinoma
- C) Uterine leiomyomas (fibroids)
- D) Desmoid tumor
Answer: C) Uterine leiomyomas (fibroids)
Uterine leiomyomas are the most common uterine tumors and a leading cause of menorrhagia and infertility in women of reproductive age.
TOPIC 10: Leiomyosarcoma
Key Points:
- 10-20% of soft tissue sarcomas; predominantly affects adults, more frequent in women
- Locations: deep extremities, retroperitoneum, great vessels
- Histology: eosinophilic spindle cells, blunt hyperchromatic nuclei, interweaving fascicles, HIGH mitotic activity + necrosis
- IHC: actin, desmin, caldesmon positive
- Retroperitoneal = worst prognosis (often fatal)
Theory MCQ 18
Which immunohistochemical markers confirm smooth muscle differentiation in leiomyosarcoma?
- A) S-100, SOX10
- B) Actin, desmin, caldesmon
- C) Myogenin, MyoD1
- D) CD34, bcl-2
Answer: B) Actin, desmin, caldesmon
These smooth muscle markers distinguish leiomyosarcoma from other spindle cell sarcomas.
Theory MCQ 19
Which histological feature DISTINGUISHES leiomyosarcoma from leiomyoma?
- A) Eosinophilic spindle cells
- B) Blunt-ended nuclei
- C) High mitotic activity and necrosis
- D) Intersecting fascicles
Answer: C) High mitotic activity and necrosis
Both share spindle cell morphology and fascicular growth, but high mitotic rate and necrosis are the key features of malignancy (leiomyosarcoma).
Clinical MCQ 12
A 60-year-old woman presents with abdominal fullness and weight loss. CT reveals a 15 cm retroperitoneal mass with central necrosis. Biopsy shows interweaving fascicles of eosinophilic spindle cells with hyperchromatic nuclei, abundant mitoses, and necrosis. IHC is positive for smooth muscle actin and desmin. What is the prognosis?
- A) Excellent - curable by excision
- B) Good - responds well to radiation
- C) Poor - retroperitoneal leiomyosarcoma often fatal due to local extension and lung metastases
- D) Intermediate - 80% 5-year survival with chemotherapy
Answer: C) Poor - retroperitoneal leiomyosarcoma often fatal
Retroperitoneal leiomyosarcoma is difficult to manage with high recurrence and metastasis rates, primarily to lungs.
TOPIC 11: Synovial Sarcoma
Key Points:
- NOT derived from synovium despite its name
- ~10% of soft tissue sarcomas; ages 20-40
- t(X;18)(p11;q11) → SS18-SSX fusion → disrupts cell cycle control
- Morphology:
- Monophasic: uniform spindle cells in tightly packed fascicles
- Biphasic: spindle cells + gland-like structures (keratin positive)
- Metastasis: lungs AND regional lymph nodes (unusual for sarcomas)
- 5-year survival: 25-62%
Theory MCQ 20
Synovial sarcoma is characterized by which chromosomal translocation?
- A) t(12;16)(q13;p11)
- B) t(11;22)(q24;q12)
- C) t(X;18)(p11;q11)
- D) t(2;13)(q35;q14)
Answer: C) t(X;18)(p11;q11)
SS18-SSX fusion is pathognomonic for synovial sarcoma. This is the most testable molecular feature.
Theory MCQ 21
Which feature distinguishes the BIPHASIC type of synovial sarcoma from the monophasic type?
- A) Higher mitotic rate
- B) Presence of gland-like structures formed by epithelioid cells (keratin positive)
- C) PAX-FOXO1 fusion
- D) MDM2 amplification
Answer: B) Gland-like structures formed by epithelioid cells that are keratin positive
Biphasic synovial sarcoma contains both spindle cells and gland-like epithelial structures. The epithelioid cells express keratins, which is unusual for a mesenchymal tumor.
Theory MCQ 22
Synovial sarcoma is unusual among sarcomas because it metastasizes to which lymph node sites, in addition to lungs?
- A) Periaortic nodes
- B) Regional lymph nodes
- C) Mediastinal nodes
- D) Inguinal nodes
Answer: B) Regional lymph nodes
Most sarcomas spread hematogenously to lungs. Synovial sarcoma is unusual in also spreading to regional lymph nodes.
Clinical MCQ 13
A 25-year-old woman presents with a slowly growing deep-seated mass near the knee for 3 years. Imaging shows a heterogeneous mass with calcifications. Biopsy reveals uniform spindle cells with scant cytoplasm in tightly packed fascicles. FISH confirms SS18-SSX fusion. What is the diagnosis?
- A) Nodular fasciitis
- B) Well-differentiated liposarcoma
- C) Monophasic synovial sarcoma
- D) Fibrosarcoma
Answer: C) Monophasic synovial sarcoma
Deep-seated peri-articular mass in a young adult + SS18-SSX fusion = synovial sarcoma. Monophasic type shows only the spindle cell component.
Clinical MCQ 14
A biopsy from a soft tissue tumor in a 30-year-old man shows both spindle cells AND gland-like structures; the glandular cells stain positive for keratin. A pathologist might initially confuse this with a carcinoma. The MOST appropriate test to confirm the diagnosis is:
- A) MDM2 FISH
- B) PAX3-FOXO1 RT-PCR
- C) SS18-SSX fusion by FISH or RT-PCR
- D) Desmin and actin IHC
Answer: C) SS18-SSX fusion detection
Biphasic synovial sarcoma with keratin-positive glands is a classic diagnostic trap. Confirming SS18-SSX fusion is diagnostic.
TOPIC 12: Undifferentiated Pleomorphic Sarcoma (UPS)
Key Points:
- Previously called malignant fibrous histiocytoma (MFH) - now obsolete
- High-grade mesenchymal tumor, unclassifiable by histology/IHC/genetics
- Complex aneuploid karyotype with genomic instability
- Deep soft tissues of extremities (thigh), middle-aged/older adults
- Morphology: large gray-white fleshy masses (10-20 cm), sheets of anaplastic spindle-to-polygonal cells with bizarre hyperchromatic nuclei, atypical mitoses, necrosis
- Metastasis: 30-50%
- Treatment: surgery + chemo ± radiation; poor prognosis
Theory MCQ 23
Undifferentiated pleomorphic sarcoma (UPS) was previously classified as:
- A) Fibrosarcoma
- B) Malignant fibrous histiocytoma (MFH)
- C) Liposarcoma
- D) Synovial sarcoma
Answer: B) Malignant fibrous histiocytoma (MFH)
MFH is now a largely obsolete term, replaced by UPS for tumors that cannot be classified along any recognized mesenchymal lineage.
Theory MCQ 24
Which karyotype pattern is characteristic of UPS (undifferentiated pleomorphic sarcoma)?
- A) Simple karyotype with specific fusion gene
- B) Euploid with few chromosomal changes
- C) Complex aneuploid/polyploid karyotype with genomic instability
- D) t(X;18) translocation
Answer: C) Complex aneuploid/polyploid karyotype
UPS belongs to the complex karyotype group (80-85% of sarcomas), with significant structural and numerical chromosomal abnormalities.
Clinical MCQ 15
A 65-year-old man presents with a 12 cm deep thigh mass. Biopsy shows sheets of large anaplastic cells with bizarre, hyperchromatic nuclei, atypical mitoses, and areas of necrosis. IHC and molecular studies fail to identify any specific lineage marker or translocation. What is the diagnosis?
- A) Rhabdomyosarcoma
- B) Synovial sarcoma
- C) Undifferentiated pleomorphic sarcoma (UPS)
- D) Leiomyosarcoma
Answer: C) Undifferentiated pleomorphic sarcoma (UPS)
UPS is diagnosed by exclusion: high-grade pleomorphic sarcoma with no identifiable differentiation. Large deep thigh mass in an older adult is classic.
Clinical MCQ 16
A patient is diagnosed with UPS of the thigh. What is the expected rate of distant metastasis?
- A) Less than 5%
- B) 10-15%
- C) 30-50%
- D) Greater than 80%
Answer: C) 30-50%
UPS is aggressive; metastasis occurs in 30-50% of cases, contributing to its poor prognosis.
RAPID-FIRE THEORY MCQs (Mixed Topics)
MCQ 25
Which soft tissue sarcoma arises from pluripotent mesenchymal stem cells (NOT mature differentiated cells)?
- A) Lipoma
- B) Rhabdomyosarcoma
- C) Nodular fasciitis
- D) Leiomyoma
Answer: B) Rhabdomyosarcoma
RMS arises from mesenchymal stem cells that acquire muscle differentiation capacity, NOT from mature skeletal muscle.
MCQ 26
Arrange the following liposarcoma subtypes from LEAST to MOST aggressive:
- A) Well-differentiated → Myxoid/round cell → Pleomorphic
- B) Pleomorphic → Myxoid → Well-differentiated
- C) Myxoid → Pleomorphic → Well-differentiated
- D) All have equal prognosis
Answer: A) Well-differentiated (indolent) → Myxoid/round cell (intermediate) → Pleomorphic (most aggressive)
MCQ 27
A soft tissue tumor shows t(17;22) translocation creating MYH9-USP6 fusion. What is the clinical implication?
- A) High risk of metastasis - start chemotherapy
- B) Benign, self-limiting lesion - conservative management or excision
- C) Intermediate malignancy - wide excision required
- D) Associated with Li-Fraumeni syndrome
Answer: B) Benign, self-limiting - nodular fasciitis
MYH9-USP6 is the fusion in nodular fasciitis. Despite clonal origin, it is benign and spontaneously regresses.
MCQ 28
Which of the following soft tissue tumors does NOT metastasize?
- A) Synovial sarcoma
- B) Undifferentiated pleomorphic sarcoma
- C) Deep fibromatosis (desmoid tumor)
- D) Pleomorphic liposarcoma
Answer: C) Deep fibromatosis (desmoid tumor)
Desmoids are locally aggressive (frequent recurrence) but do not metastasize. This is a classic exam point.
MCQ 29
Rhabdomyosarcoma is the most common soft tissue sarcoma in which age group?
- A) Neonates (<1 year)
- B) Childhood and adolescence (<20 years)
- C) Middle adulthood (40-60 years)
- D) Elderly (>70 years)
Answer: B) Childhood and adolescence (<20 years)
RMS is the most common soft tissue sarcoma in children and adolescents. Pleomorphic RMS is the exception, occurring in adults.
MCQ 30
A biphasic tumor with spindle cells AND keratin-positive glandular structures near the knee in a 28-year-old: the MOST characteristic molecular finding is:
- A) MDM2 amplification
- B) t(2;13) PAX3-FOXO1
- C) t(X;18) SS18-SSX
- D) MYH9-USP6 fusion
Answer: C) t(X;18) SS18-SSX
Biphasic tumor with keratin-positive glands near a joint in a young adult = biphasic synovial sarcoma. SS18-SSX is pathognomonic.
QUICK REFERENCE SUMMARY TABLE
| Tumor | Key Molecular Marker | Malignant? | Classic Clinical Feature |
|---|---|---|---|
| Lipoma | - | No | Most common adult soft tissue tumor |
| Liposarcoma (WD) | MDM2 amp (12q13-15) | Yes | Indolent; retroperitoneum in 50-60s |
| Liposarcoma (Myxoid) | t(12;16) | Yes | Arborizing capillaries; intermediate |
| Liposarcoma (Pleomorphic) | Complex karyotype | Yes | Lipoblasts; most aggressive |
| Nodular Fasciitis | MYH9-USP6 | No | Rapid growth, young adult, trauma |
| Superficial Fibromatosis | - | No | Dupuytren/Peyronie/plantar |
| Deep Fibromatosis (Desmoid) | APC/CTNNB1 | No* | FAP, abdominal; no metastasis |
| RMS - Embryonal | Heterogeneous | Yes | Children; botryoid in hollow viscera |
| RMS - Alveolar | PAX3/PAX7-FOXO1 | Yes | Worst RMS prognosis |
| RMS - Pleomorphic | Heterogeneous | Yes | Adults; needs myogenin IHC |
| Leiomyoma | FH (multiple cutaneous) | No | Uterus; menorrhagia/infertility |
| Leiomyosarcoma | Complex karyotype | Yes | Actin/desmin/caldesmon+ |
| Synovial Sarcoma | SS18-SSX t(X;18) | Yes | Peri-articular; lymph node mets |
| UPS (ex-MFH) | Complex karyotype | Yes | Diagnosis of exclusion; thigh in older adult |
*Locally aggressive, no metastasis
This covers all major topics from your PDF across 30 MCQs (16 theory + 14 clinical) organized into 12 topic-based flashcard sections. Each question tests a high-yield concept directly from your lecture material.
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