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10. Pathology and Oncology MCQs

Practice Set 189 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 3761

Topic: 10. Pathology and Oncology

During physical examination of an upper extremity soft tissue mass suspected to be a peripheral nerve sheath tumor, the clinician elicits Valleix's sign. Which clinical finding best describes the mobility of these tumors?

. Freely mobile in all planes
. Mobile longitudinally but fixed transversely
. Mobile transversely but restricted longitudinally
. Completely fixed to underlying bone and fascia
. Pulsatile and expansile with dependency

Correct Answer & Explanation

. Mobile transversely but restricted longitudinally

Explanation

Peripheral nerve sheath tumors are tethered to the nerve of origin. Consequently, they are mobile perpendicular (transversely) to the axis of the nerve but restricted parallel (longitudinally) to it.

Question 3762

Topic: 10. Pathology and Oncology

A 35-year-old male with Schwannomatosis presents with multiple painful peripheral nerve tumors. Which gene mutations are most commonly implicated in the pathogenesis of familial Schwannomatosis in the absence of bilateral vestibular schwannomas?

. NF1 and TP53
. SMARCB1 and LZTR1
. EXT1 and EXT2
. BRCA1 and BRCA2
. COL1A1 and COL1A2

Correct Answer & Explanation

. SMARCB1 and LZTR1

Explanation

Schwannomatosis is distinct from NF1 and NF2 and is characterized by multiple painful schwannomas without vestibular involvement. It is frequently associated with mutations in the SMARCB1 and LZTR1 genes.

Question 3763

Topic: 10. Pathology and Oncology

A pathologist is using a neurofilament stain to differentiate between a schwannoma and a neurofibroma. Which pattern of axonal staining strongly favors the diagnosis of a schwannoma?

. Axons are completely absent within the tumor and the surrounding capsule.
. Axons are uniformly dispersed throughout the entire tumor matrix.
. Axons are trapped centrally within dense myxoid stroma.
. Axons are predominantly displaced to the thin peripheral capsule.
. Axons exhibit severe fragmentation and wallerian degeneration within the core.

Correct Answer & Explanation

. Axons are predominantly displaced to the thin peripheral capsule.

Explanation

Schwannomas are encapsulated and push the native nerve fascicles outward. A neurofilament stain will show axons draped over the peripheral capsule, whereas in a neurofibroma, axons traverse through the tumor mass.

Question 3764

Topic: 10. Pathology and Oncology

A 22-year-old with NF1 has a known large plexiform neurofibroma of the thigh. He reports a 2-month history of rapid tumor enlargement and new, unrelenting rest pain. What is the most appropriate next step in management?

. Immediate marginal enucleation of the tumor
. PET/CT scan followed by targeted core needle biopsy
. Initiation of high-dose oral corticosteroids
. Routine surveillance MRI in 6 months
. Empiric radiation therapy to the limb

Correct Answer & Explanation

. PET/CT scan followed by targeted core needle biopsy

Explanation

Rapid growth and new pain in a plexiform neurofibroma strongly suggest malignant transformation to an MPNST. An FDG-PET/CT helps identify the most metabolically active areas to target for biopsy.

Question 3765

Topic: Soft Tissue Tumors & Metastasis

Which of the following immunohistochemical staining profiles is most characteristic of a benign sporadic schwannoma?

. Weak, patchy S-100 positivity and absent SOX10
. Uniform, strong, diffuse S-100 and SOX10 positivity
. Strong positivity for SMA and Desmin
. Diffuse positivity for Cytokeratin and EMA
. CD34 positive, S-100 negative

Correct Answer & Explanation

. Uniform, strong, diffuse S-100 and SOX10 positivity

Explanation

Schwannomas are composed entirely of neoplastic Schwann cells, showing strong, diffuse, and uniform positivity for S-100 and SOX10. Neurofibromas exhibit only patchy S-100 staining due to their mixed cellular composition.

Question 3766

Topic: 10. Pathology and Oncology

What is the expected outcome regarding malignant transformation in a patient with a solitary, sporadic schwannoma of the ulnar nerve?

. A 10-15% lifetime risk of transforming into MPNST
. Transformation risk is directly proportional to the size of the lesion
. Malignant transformation is extremely rare, approaching 0%
. It requires prophylactic radiation to prevent transformation
. Transformation typically occurs within 5 years of initial presentation

Correct Answer & Explanation

. Malignant transformation is extremely rare, approaching 0%

Explanation

Unlike plexiform neurofibromas in NF1, solitary sporadic schwannomas have an exceptionally low risk of malignant transformation, essentially considered zero in most clinical series.

Question 3767

Topic: Soft Tissue Tumors & Metastasis

A 50-year-old patient undergoes uncomplicated marginal enucleation of a 3-cm median nerve schwannoma in the mid-forearm. Postoperatively, she experiences new numbness and tingling in the thumb and index finger without motor weakness. What is the most appropriate management?

. Immediate re-exploration for nerve repair
. Emergent compartment fasciotomies
. Observation and reassurance as this neuropraxia typically resolves
. Prescription of disease-modifying antirheumatic drugs (DMARDs)
. Immediate nerve grafting using the sural nerve

Correct Answer & Explanation

. Observation and reassurance as this neuropraxia typically resolves

Explanation

Transient sensory neuropraxia is common following schwannoma enucleation due to intraoperative manipulation and traction on the fascicles. It almost always resolves with conservative management and observation.

Question 3768

Topic: 10. Pathology and Oncology

Which of the following describes the characteristic gross pathological appearance and architectural relationship of a solitary intraneural neurofibroma to its parent nerve?

. A well-encapsulated mass easily separated from the nerve fibers
. A cystic lesion filled with mucin adjacent to the epineurium
. A fusiform, unencapsulated expansion of the nerve with fascicles entering and exiting the mass
. A lobulated mass with a distinct stalk arising from the perineurium
. A calcified nodule completely obliterating the vasa nervorum

Correct Answer & Explanation

. A fusiform, unencapsulated expansion of the nerve with fascicles entering and exiting the mass

Explanation

Solitary intraneural neurofibromas present as fusiform, unencapsulated expansions of the nerve. The nerve fascicles pass directly through the substance of the tumor, making nerve-sparing resection nearly impossible.

Question 3769

Topic: 10. Pathology and Oncology

Which of the following clinical features most reliably distinguishes a malignant peripheral nerve sheath tumor (MPNST) from a benign neurofibroma?

. Presence of a positive Tinel's sign over the mass
. A hyperintense signal on T2-weighted MRI
. Rapid size increase, unremitting rest pain, and new neurologic deficits
. Location of the tumor in the major nerves of the lower extremity
. The "split-fat" sign on MRI

Correct Answer & Explanation

. Rapid size increase, unremitting rest pain, and new neurologic deficits

Explanation

While benign nerve tumors can cause a Tinel's sign and have characteristic MRI features, rapid exponential growth, intractable rest pain, and new motor/sensory deficits are the clinical hallmarks of malignant transformation.

Question 3770

Topic: 10. Pathology and Oncology

A biopsy of a large sciatic nerve mass in an NF1 patient reveals pleomorphic spindle cells, frequent mitoses, necrosis, and loss of H3K27me3 expression. Which of the following best describes the prognosis and primary treatment?

. Excellent prognosis; treated with marginal excision
. Poor prognosis; requires wide surgical resection and multimodal therapy
. Benign natural history; managed with observation only
. Highly responsive to standard chemotherapy; surgery is contraindicated
. Self-limiting lesion; requires intralesional steroid injections

Correct Answer & Explanation

. Poor prognosis; requires wide surgical resection and multimodal therapy

Explanation

The biopsy shows an MPNST, a high-grade sarcoma associated with a poor prognosis. Treatment demands wide surgical resection, often combined with neoadjuvant or adjuvant radiation and chemotherapy.

Question 3771

Topic: 10. Pathology and Oncology

A 60-year-old female is incidentally found to have an asymptomatic 2-cm fusiform mass in the posterior tibial nerve on an MRI obtained for an ankle sprain. The mass has a target sign and biopsy confirms a benign neurofibroma. What is the most appropriate management?

. Immediate wide surgical resection with negative margins
. Marginal enucleation utilizing microscopic technique
. Observation with serial clinical exams and imaging
. Primary radiation therapy
. Amputation below the knee

Correct Answer & Explanation

. Observation with serial clinical exams and imaging

Explanation

Asymptomatic, benign intraneural neurofibromas should be managed with observation. Resection would inevitably sacrifice the functional posterior tibial nerve, resulting in significant plantar sensory and motor loss.

Question 3772

Topic: 10. Pathology and Oncology

Under the microscope, a peripheral nerve sheath tumor displays Antoni A tissue. What specific microscopic structure, composed of palisading nuclei surrounding eosinophilic zones of cellular processes, is diagnostic of this region?

. Homer-Wright rosettes
. Verocay bodies
. Psammoma bodies
. Lisch nodules
. Asteroid bodies

Correct Answer & Explanation

. Verocay bodies

Explanation

Verocay bodies are highly characteristic of the Antoni A (hypercellular) areas of a schwannoma. They consist of stacked arrangements of elongated palisading nuclei alternating with anuclear fibrillary zones.

Question 3773

Topic: Soft Tissue Tumors & Metastasis

What is the primary cellular origin of both Schwannomas and Neurofibromas?

. Fibroblasts
. Perineurial cells
. Neural crest-derived Schwann cells
. Mesenchymal stem cells
. Endothelial cells

Correct Answer & Explanation

. Neural crest-derived Schwann cells

Explanation

Both schwannomas and neurofibromas arise from Schwann cells, which are derived from the embryonic neural crest. Despite differing architectures and mixed cellularity in neurofibromas, the neoplastic driver is the Schwann cell.

Question 3774

Topic: 10. Pathology and Oncology

A 28-year-old patient with NF1 requires resection of a large, symptomatic, benign intraneural neurofibroma of the radial nerve. Which of the following preoperative discussions is most critical regarding expected postoperative outcomes?

. There is a 100% chance of restoring normal nerve function immediately.
. The surgery involves an extremely high likelihood of permanent radial nerve palsy requiring tendon transfers.
. The tumor can easily be peeled away from the normal nerve without risk.
. Postoperative radiation is mandatory to prevent benign recurrence.
. The procedure will definitively cure their underlying genetic condition.

Correct Answer & Explanation

. The surgery involves an extremely high likelihood of permanent radial nerve palsy requiring tendon transfers.

Explanation

Because an intraneural neurofibroma incorporates the nerve fascicles within its substance, complete excision requires sacrificing that nerve segment. The patient must be prepared for the resulting functional loss and likely need for reconstruction.

Question 3775

Topic: Soft Tissue Tumors & Metastasis

A 40-year-old patient presents with a slow-growing, painful mass in the volar forearm. Intraoperatively, the mass is found to be encapsulated and eccentrically located on the median nerve. Which of the following is the most likely intraoperative characteristic of this lesion?

. Inseparable from the nerve fascicles, requiring segmental resection
. Eccentrically located with identifiable and separable nerve fascicles
. Composed of multiple grouped fascicles resembling a "bag of worms"
. Originating from the epineurium with minimal vascularity
. Lacking a true capsule and infiltrating adjacent muscle tissue

Correct Answer & Explanation

. Eccentrically located with identifiable and separable nerve fascicles

Explanation

Schwannomas are typically eccentrically located and encapsulated, allowing for enucleation while sparing the nerve fascicles. Neurofibromas, in contrast, are usually centrally located and inextricably intertwined with the fascicles.

Question 3776

Topic: 10. Pathology and Oncology

A biopsy of a peripheral nerve sheath tumor reveals a biphasic architecture with hypercellular areas containing palisading nuclei and hypocellular, myxoid areas. What are the hypercellular regions with palisading nuclei commonly called?

. Antoni B areas
. Antoni A areas
. Verocay bodies
. Homer-Wright rosettes
. Lisch nodules

Correct Answer & Explanation

. Antoni A areas

Explanation

The hypercellular areas in a schwannoma are called Antoni A areas, which often contain palisading nuclei. Verocay bodies are specific formations of these palisading nuclei within the Antoni A regions.

Question 3777

Topic: 10. Pathology and Oncology

A 25-year-old patient with bilateral vestibular schwannomas is evaluated. This condition is associated with a mutation in a tumor suppressor gene. What is the correct gene and its chromosomal location?

. Neurofibromin on chromosome 17
. Merlin on chromosome 22
. SMARCB1 on chromosome 22
. p53 on chromosome 17
. Rb on chromosome 13

Correct Answer & Explanation

. Merlin on chromosome 22

Explanation

Bilateral vestibular schwannomas are the hallmark of Neurofibromatosis Type 2 (NF2). This condition is caused by a mutation in the merlin (schwannomin) gene located on chromosome 22.

Question 3778

Topic: 10. Pathology and Oncology

A patient with Neurofibromatosis Type 1 (NF1) presents with rapid enlargement and increasing pain in a long-standing plexiform neurofibroma. What is the most likely malignant transformation?

. Malignant melanoma
. Malignant peripheral nerve sheath tumor (MPNST)
. Fibrosarcoma
. Synovial sarcoma
. Epithelioid sarcoma

Correct Answer & Explanation

. Malignant peripheral nerve sheath tumor (MPNST)

Explanation

Plexiform neurofibromas in NF1 carry a 5-10% lifetime risk of malignant transformation into Malignant Peripheral Nerve Sheath Tumors (MPNST). Rapid growth and pain are classic warning signs.

Question 3779

Topic: Soft Tissue Tumors & Metastasis

Which of the following is the most appropriate surgical management for a solitary, symptomatic, centrally located neurofibroma involving a major motor nerve?

. Simple enucleation sparing the fascicles
. Marginal excision with epineural repair
. Segmental nerve resection and nerve grafting
. Wide local excision and postoperative radiation
. Observation only

Correct Answer & Explanation

. Segmental nerve resection and nerve grafting

Explanation

Unlike schwannomas, solitary neurofibromas grow within the nerve, spreading apart the fascicles making them inseparable from the tumor. Removal typically requires segmental nerve resection and subsequent nerve grafting.

Question 3780

Topic: 10. Pathology and Oncology

On a T2-weighted MRI, a benign peripheral nerve sheath tumor demonstrates a "target sign" characterized by a hyperintense rim and a hypointense center. What histological feature corresponds to the central hypointensity?

. Myxoid degeneration
. Dense fibrocollagenous tissue (Antoni A)
. Acute hemorrhage
. Cystic necrosis
. Dystrophic calcification

Correct Answer & Explanation

. Dense fibrocollagenous tissue (Antoni A)

Explanation

The MRI "target sign" in nerve sheath tumors shows a hyperintense rim (myxoid Antoni B tissue) and a hypointense center. The hypointense center corresponds to dense, cellular fibrocollagenous tissue (Antoni A areas).

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