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10. Pathology and Oncology MCQs

Practice Set 172 of 351

This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 3421

Topic: 10. Pathology and Oncology

A 45-year-old male presents with chronic knee pain, mechanical catching, and swelling. Radiographs show multiple, uniform-sized calcified loose bodies within the joint space.

What is the primary pathological mechanism underlying this condition?

. Metaplastic cartilage formation within the synovium
. Autoimmune destruction of articular cartilage
. Primary malignant transformation of resting chondrocytes
. Deposition of calcium pyrophosphate crystals
. Viral-induced proliferation of the synovial lining

Correct Answer & Explanation

. Metaplastic cartilage formation within the synovium

Explanation

Synovial chondromatosis is a benign condition characterized by metaplastic cartilage formation in the synovial membrane. These nodules can detach, ossify, and become multiple loose bodies of relatively uniform size. There is a rare but recognized risk of secondary malignant transformation to chondrosarcoma.

Question 3422

Topic: 10. Pathology and Oncology

A 50-year-old male discovers a painless, deep-seated 8 cm mass in his anterior thigh. Plain radiographs are unremarkable except for a soft tissue shadow.

What is the most appropriate next step in management?

. Open incisional biopsy
. Fine needle aspiration
. MRI of the extremity with and without contrast
. Whole-body PET scan
. Immediate wide excisional biopsy

Correct Answer & Explanation

. MRI of the extremity with and without contrast

Explanation

MRI with and without contrast is the gold standard for evaluating a suspected soft tissue sarcoma before any biopsy. It delineates the anatomical extent, compartment involvement, and proximity to neurovascular structures. Biopsy performed prior to advanced imaging can obscure tumor margins and complicate definitive resection.

Question 3423

Topic: 10. Pathology and Oncology

A 30-year-old female undergoes resection of a slow-growing, calcified mass near her knee joint. Histology reveals a biphasic pattern of spindle cells and epithelial cells. Which of the following translocations is diagnostic for this tumor?

. t(11;22)
. t(9;22)
. t(X;18)
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene. Despite its name, it rarely arises directly from the joint synovium, typically occurring in the periarticular soft tissues of young adults. It often presents with a biphasic or monophasic spindle cell morphology.

Question 3424

Topic: Bone Tumors

An 8-year-old girl is evaluated for precocious puberty, irregular cafe-au-lait macules, and recurrent fractures. Radiographs reveal polyostotic expansile, radiolucent bone lesions with a ground-glass appearance. What is the underlying genetic mutation?

. EXT1
. FGFR3
. GNAS1
. COL1A1
. RUNX2

Correct Answer & Explanation

. GNAS1

Explanation

This patient presents with McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, cafe-au-lait spots (coast of Maine), and endocrine abnormalities. It is caused by an activating post-zygotic somatic mutation in the GNAS1 gene. This leads to increased intracellular cAMP, disrupting normal osteoblast differentiation.

Question 3425

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with fever, focal mid-thigh pain, and an elevated ESR. Radiographs show a diaphyseal destructive lesion with an "onion-skin" periosteal reaction. Biopsy shows small round blue cells strongly expressing CD99. What translocation is characteristic of this tumor?

. t(11;22)
. t(X;18)
. t(12;16)
. t(17;22)
. t(12;22)

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is a highly aggressive, small round blue cell tumor often found in the diaphysis of long bones in children. It is defined by the t(11;22)(q24;q12) translocation, creating the EWS-FLI1 fusion protein. CD99 (MIC2) is a sensitive, though not perfectly specific, immunohistochemical marker.

Question 3426

Topic: 10. Pathology and Oncology
An 18-year-old male with conventional osteosarcoma of the distal femur completes neoadjuvant chemotherapy followed by limb-salvage surgery. Which of the following pathological findings from the resected specimen is the most important prognostic factor for overall survival?
. Overall size of the tumor mass
. Distance of the tumor from the articular cartilage
. Percentage of tumor necrosis
. Presence of telangiectatic histological features
. Degree of periosteal elevation (Codman's triangle)

Correct Answer & Explanation

. Percentage of tumor necrosis

Explanation

The histological response to neoadjuvant chemotherapy, defined as the percentage of tumor necrosis, is the strongest prognostic indicator for overall survival in osteosarcoma. A good response is typically defined as greater than 90% tumor necrosis (Huvos grade III/IV). Poor responders may require altered postoperative chemotherapy regimens.

Question 3427

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a 10 cm destructive lesion in the ilium exhibiting "rings and arcs" calcification and cortical breakthrough. A biopsy confirms grade II chondrosarcoma. What is the most appropriate definitive management?

. Neoadjuvant chemotherapy followed by wide resection
. Definitive high-dose radiation therapy
. Wide surgical resection alone
. Intralesional curettage with liquid nitrogen cryotherapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcoma is notoriously resistant to both chemotherapy and radiation therapy due to its poor vascularity and slow growth. Therefore, the mainstay of treatment for intermediate to high-grade lesions (or pelvic lesions) is wide surgical resection alone. Achieving negative margins is critical for preventing local recurrence.

Question 3428

Topic: Soft Tissue Tumors & Metastasis

A 45-year-old male undergoes excision of a deep thigh mass. Pathology demonstrates a myxoid stroma, a prominent plexiform ("chicken-wire") capillary network, and scattered lipoblasts. Which genetic alteration is most likely present?

. t(11;22)
. t(X;18)
. t(12;16)
. t(12;22)
. t(2;13)

Correct Answer & Explanation

. t(12;16)

Explanation

Myxoid liposarcoma is characterized by the t(12;16)(q13;p11) translocation, resulting in the FUS-DDIT3 fusion gene. It commonly presents in the deep thigh of middle-aged adults and has a distinct "chicken-wire" vascular pattern. This subtype of liposarcoma is known to be highly sensitive to radiation therapy.

Question 3429

Topic: 10. Pathology and Oncology

When performing a core needle biopsy for a suspected soft tissue sarcoma of the extremity, which of the following is a critical technical principle?

. Transverse incisions are preferred for optimal cosmesis
. The biopsy tract should be placed through unaffected muscle bellies to ensure a clean sample
. The biopsy tract must be placed in line with the planned definitive longitudinal surgical excision
. Meticulous hemostasis is not necessary as the tract will be excised
. The biopsy should aim for the necrotic center of the tumor

Correct Answer & Explanation

. The biopsy tract must be placed in line with the planned definitive longitudinal surgical excision

Explanation

Biopsy tracts for musculoskeletal sarcomas must be longitudinally oriented and placed within the planned excision field. This ensures the entire tract can be excised en bloc with the tumor during definitive surgery. Contaminating new compartments or using transverse incisions compromises limb-salvage options.

Question 3430

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with a rapidly enlarging calf mass. Biopsy reveals small round blue cells with skeletal muscle differentiation. Cytogenetic analysis identifies a t(2;13) translocation. What is the most likely diagnosis?

. Undifferentiated pleomorphic sarcoma
. Synovial sarcoma
. Alveolar rhabdomyosarcoma
. Clear cell sarcoma
. Myxoid liposarcoma

Correct Answer & Explanation

. Myxoid liposarcoma

Explanation

Alveolar rhabdomyosarcoma is an aggressive soft tissue sarcoma affecting older children and adolescents, characterized by the t(2;13) translocation forming the PAX3-FOXO1 fusion gene. It carries a worse prognosis compared to the embryonal variant. Treatment requires a multidisciplinary approach with chemotherapy, surgery, and radiation.

Question 3431

Topic: 10. Pathology and Oncology

A 15-year-old boy has multiple painless, bony bumps around his knees and shoulders that have been growing slowly since childhood. His father has a similar condition. What is the primary function of the genes most commonly mutated in this disorder?

. Synthesis of heparan sulfate proteoglycans
. Signaling through fibroblast growth factor receptors
. Formation of Type I collagen triple helices
. Sulfate transport across the cell membrane
. G-protein coupled receptor signaling

Correct Answer & Explanation

. Synthesis of heparan sulfate proteoglycans

Explanation

Multiple hereditary exostoses (osteochondromatosis) is an autosomal dominant condition caused by mutations in the EXT1 or EXT2 genes. These genes encode glycosyltransferases essential for the synthesis of heparan sulfate proteoglycans. A major clinical concern is the risk of malignant transformation into secondary chondrosarcoma.

Question 3432

Topic: 10. Pathology and Oncology

A 70-year-old man presents with dull aching pain in his right leg, increasing hat size, and hearing loss. Radiographs show bowing of the tibia with cortical thickening and coarsened trabeculae. Blood tests reveal isolated significant elevation of alkaline phosphatase. What is the primary cellular pathogenesis?

. Excessive osteoblastic bone formation followed by secondary resorption
. Increased osteoclastic bone resorption followed by disorganized osteoblastic bone formation
. Primary defect in mineralization of normal osteoid matrix
. Defect in Type I collagen synthesis leading to brittle bone
. Failure of endochondral ossification at the physis

Correct Answer & Explanation

. Increased osteoclastic bone resorption followed by disorganized osteoblastic bone formation

Explanation

Paget's disease of bone begins with an intense phase of osteoclastic bone resorption, followed by a compensatory but disorganized (woven) osteoblastic bone formation. This results in structurally weak, enlarged bones prone to deformity and fracture. There is a small risk (about 1%) of malignant transformation to osteosarcoma.

Question 3433

Topic: 10. Pathology and Oncology

A 22-year-old man undergoes biopsy of a painless, deep, 3 cm mass on the plantar aspect of his foot. Histology reveals nests of polygonal cells with prominent nucleoli. Immunohistochemistry is positive for HMB-45 and S-100. Which translocation is characteristic of this "melanoma of soft parts"?

. t(11;22)
. t(12;22)
. t(X;18)
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(12;22)

Explanation

Clear cell sarcoma, historically termed melanoma of soft parts, often arises in the foot/ankle of young adults and shares immunophenotypic markers with melanoma (S-100, HMB-45). It is driven by the t(12;22)(q13;q12) translocation, producing the EWSR1-ATF1 fusion protein. It has a high propensity for metastasis to regional lymph nodes.

Question 3434

Topic: 10. Pathology and Oncology

A 35-year-old female presents with a slow-growing, multi-nodular indurated plaque on her trunk. Biopsy reveals a spindle cell tumor arranged in a "storiform" pattern that stains strongly positive for CD34. The translocation t(17;22) is identified. What is the most appropriate surgical management?

. Intralesional curettage
. Marginal excision just outside the pseudocapsule
. Wide local excision with 2 to 3 cm margins or Mohs micrographic surgery
. Neoadjuvant chemotherapy followed by wide excision
. Definitive external beam radiation therapy

Correct Answer & Explanation

. Wide local excision with 2 to 3 cm margins or Mohs micrographic surgery

Explanation

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive cutaneous sarcoma characterized by the COL1A1-PDGFB fusion gene t(17;22) and CD34 positivity. Due to extensive subclinical, tentacle-like local spread, standard treatment requires wide local excision with 2 to 3 cm margins or Mohs micrographic surgery to prevent recurrence.

Question 3435

Topic: 10. Pathology and Oncology

A 68-year-old male presents with a rapidly enlarging, deep-seated 12 cm soft tissue mass in the posterior thigh.

Core biopsy shows highly pleomorphic spindle cells with frequent, atypical mitoses, severe nuclear atypia, and no specific line of cellular differentiation. What is the most likely diagnosis?

. Myxoid liposarcoma
. Undifferentiated pleomorphic sarcoma (UPS)
. Synovial sarcoma
. Dermatofibrosarcoma protuberans
. Clear cell sarcoma

Correct Answer & Explanation

. Undifferentiated pleomorphic sarcoma (UPS)

Explanation

Undifferentiated pleomorphic sarcoma (formerly malignant fibrous histiocytoma, MFH) is one of the most common high-grade soft tissue sarcomas in older adults. It is a diagnosis of exclusion characterized by high-grade pleomorphic cells without a specific line of differentiation. It frequently metastasizes to the lungs.

Question 3436

Topic: 10. Pathology and Oncology

A 42-year-old male presents with knee pain and catching. Radiographs are shown.

What is the primary pathophysiologic mechanism for this condition?

. Metaplastic transformation of the synovial lining
. Clonal proliferation of chondroblasts
. Fragmentation of articular cartilage
. Infectious seeding of the joint space
. Deposition of calcium pyrophosphate

Correct Answer & Explanation

. Metaplastic transformation of the synovial lining

Explanation

Primary synovial chondromatosis involves benign metaplasia of the synovial lining, leading to the formation of cartilaginous loose bodies that may ossify. Secondary synovial chondromatosis occurs due to degenerative joint disease causing cartilage fragmentation.

Question 3437

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a slowly enlarging, painless mass near her ankle. Radiographs show punctate calcifications in the soft tissues.

A biopsy reveals a biphasic spindle and epithelial cell pattern. Which cytogenetic abnormality is diagnostic?

. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(11;22)(q24;q12)
. t(12;22)(q13;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, resulting in the SYT-SSX fusion gene. It often presents with soft tissue calcifications near a joint in young adults.

Question 3438

Topic: 10. Pathology and Oncology

A 45-year-old man undergoes resection of a large intramuscular thigh mass. Histology demonstrates a plexiform capillary network and lipoblasts in a myxoid stroma. Which of the following is essential in the staging of this specific tumor?

. Sentinel lymph node biopsy
. Whole spine MRI
. Bone marrow aspirate
. Cerebrospinal fluid analysis
. PET scan only

Correct Answer & Explanation

. Whole spine MRI

Explanation

Myxoid liposarcoma has a unique propensity to metastasize to extrapulmonary soft tissue and bone sites, particularly the spine. Staging requires a whole-spine MRI in addition to standard chest imaging.

Question 3439

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a firm, ulcerated nodule on the volar aspect of his right index finger, initially misdiagnosed as a wart. Biopsy reveals a nodular proliferation of atypical epithelioid cells with central necrosis. Which of the following characteristics is true regarding this malignancy?

. It has a high rate of lymphatic metastasis
. It is uniformly positive for S-100 and HMB-45
. It typically demonstrates a t(11;22) translocation
. It originates primarily from skeletal muscle
. It has an excellent prognosis with marginal excision

Correct Answer & Explanation

. It has a high rate of lymphatic metastasis

Explanation

Epithelioid sarcoma commonly presents in the distal extremities of young adults and is notable for a high rate of lymphatic metastasis. Proximal subtypes show loss of INI-1, and treatment requires aggressive resection.

Question 3440

Topic: 10. Pathology and Oncology

A 30-year-old female presents with a deep-seated, painful mass associated with her Achilles tendon. Histology shows nested cells with clear cytoplasm separated by fibrous septa. Immunohistochemistry is strongly positive for HMB-45 and Melan-A. What is the characteristic translocation?

. t(X;18) SYT-SSX
. t(12;16) FUS-DDIT3
. t(12;22) EWS-ATF1
. t(2;13) PAX3-FOXO1
. t(9;22) BCR-ABL

Correct Answer & Explanation

. t(12;22) EWS-ATF1

Explanation

Clear cell sarcoma, also known as melanoma of soft parts, typically involves tendons or aponeuroses and is driven by the t(12;22) EWS-ATF1 translocation. Unlike cutaneous melanoma, it lacks a BRAF mutation.

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