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Soft Tissue Tumors & Metastasis MCQs

Practice Set 4 of 6

This practice set contains high-yield board review questions covering key concepts in Soft Tissue Tumors & Metastasis. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 61

Topic: Soft Tissue Tumors & Metastasis

A 14-year-old boy presents with a massive, diffuse, tortuous swelling of his right upper extremity. Palpation of the mass yields a sensation described as a "bag of worms." This lesion is considered pathognomonic for which condition?

. Schwannomatosis
. Neurofibromatosis type 2
. Neurofibromatosis type 1
. Multiple Endocrine Neoplasia type 2B
. Sturge-Weber syndrome

Correct Answer & Explanation

. Neurofibromatosis type 1

Explanation

The "bag of worms" palpation refers to a plexiform neurofibroma. This lesion involves multiple nerve fascicles and branches, and is strictly pathognomonic for Neurofibromatosis type 1 (NF1).

Question 62

Topic: Soft Tissue Tumors & Metastasis

A patient presents with multiple distinct schwannomas in the extremities but lacks vestibular schwannomas. Genetic testing reveals a mutation distinct from NF1 and NF2. Which gene is most commonly implicated in this condition (Schwannomatosis)?

. SMARCB1 (INI1) or LZTR1
. APC
. TP53
. Rb1
. PTEN

Correct Answer & Explanation

. SMARCB1 (INI1) or LZTR1

Explanation

Schwannomatosis is a distinct clinical entity from NF1 and NF2, characterized by multiple schwannomas without bilateral acoustic neuromas. It is most commonly associated with mutations in the SMARCB1 (INI1) or LZTR1 genes.

Question 63

Topic: Soft Tissue Tumors & Metastasis
A 12-year-old boy is suspected of having Neurofibromatosis type 1. Which of the following is an established clinical diagnostic criterion for NF1 according to the NIH guidelines?
. Presence of 2 or more café-au-lait macules greater than 5 mm
. Presence of 4 or more café-au-lait macules greater than 15 mm
. A solitary neurofibroma of any size
. Presence of 6 or more café-au-lait macules (size >5 mm prepubertal or >15 mm postpubertal)
. Bilateral acoustic neuromas on MRI

Correct Answer & Explanation

. Presence of 6 or more café-au-lait macules (size >5 mm prepubertal or >15 mm postpubertal)

Explanation

The NIH diagnostic criteria for NF1 require at least two features, one of which can be the presence of 6 or more café-au-lait spots (measuring >5 mm in prepubertal individuals and >15 mm in postpubertal individuals).

Question 64

Topic: Soft Tissue Tumors & Metastasis

Which of the following describes the cellular composition of a neurofibroma compared to a schwannoma?

. Neurofibromas contain a heterogeneous mix of Schwann cells, perineurial cells, fibroblasts, and mast cells.
. Neurofibromas are composed purely of monoclonal neoplastic Schwann cells.
. Neurofibromas lack fibroblasts and are composed exclusively of mast cells.
. Schwannomas contain a dense population of axons within their central core.
. Schwannomas lack S-100 expressing cells entirely.

Correct Answer & Explanation

. Neurofibromas contain a heterogeneous mix of Schwann cells, perineurial cells, fibroblasts, and mast cells.

Explanation

Neurofibromas are heterogeneous, unencapsulated tumors containing Schwann cells, fibroblasts, perineurial-like cells, and mast cells admixed with axons. In contrast, schwannomas are predominantly homogeneous proliferations of neoplastic Schwann cells.

Question 65

Topic: Soft Tissue Tumors & Metastasis

Immunohistochemical staining is performed on a suspected peripheral nerve sheath tumor to differentiate between a schwannoma and a neurofibroma. Which staining profile most strongly supports a diagnosis of a schwannoma?

. Diffuse, strong S-100 positivity and presence of SOX10
. Patchy, weak S-100 positivity with CD34 positive fibroblasts
. Diffuse Desmin and MyoD1 positivity
. Loss of H3K27me3 expression
. Strong epithelial membrane antigen (EMA) positivity in the core

Correct Answer & Explanation

. Diffuse, strong S-100 positivity and presence of SOX10

Explanation

Schwannomas are composed almost entirely of Schwann cells, resulting in diffuse and strong S-100 and SOX10 positivity. Neurofibromas contain a mix of cell types, leading to patchy S-100 staining and CD34 positivity in the stromal network.

Question 66

Topic: Soft Tissue Tumors & Metastasis

A 35-year-old patient presents with multiple painful peripheral schwannomas but lacks bilateral vestibular schwannomas. Genetic testing reveals a mutation in the SMARCB1 (INI1) gene. What is the most likely diagnosis?

. Schwannomatosis
. Neurofibromatosis type 1
. Neurofibromatosis type 2
. Multiple Endocrine Neoplasia type 2B
. Li-Fraumeni syndrome

Correct Answer & Explanation

. Schwannomatosis

Explanation

Schwannomatosis is a distinct genetic condition characterized by multiple schwannomas without the vestibular involvement seen in NF2. It is typically associated with mutations in the SMARCB1 (INI1) or LZTR1 genes.

Question 67

Topic: Soft Tissue Tumors & Metastasis

During the histopathological review of an excised peripheral soft tissue mass, the pathologist identifies Verocay bodies. What do these specific structures consist of?

. Parallel rows of palisading Schwann cell nuclei separated by anucleate eosinophilic processes
. Wavy collagen bundles interspersed with mast cells
. Clusters of foamy histiocytes surrounding areas of necrosis
. Multinucleated giant cells engulfing hemosiderin
. Rosettes of primitive neuroectodermal cells around a central neuropil core

Correct Answer & Explanation

. Parallel rows of palisading Schwann cell nuclei separated by anucleate eosinophilic processes

Explanation

Verocay bodies are characteristic histologic features found in the Antoni A areas of schwannomas. They consist of stacked, parallel rows of palisading nuclei separated by pink, anucleate zones of cytoplasmic processes.

Question 68

Topic: Soft Tissue Tumors & Metastasis

Which of the following clinical or anatomical characteristics accurately differentiates a solitary neurofibroma from a schwannoma?

. Neurofibromas incorporate nerve fascicles throughout the tumor substance
. Schwannomas lack a true epineurial capsule
. Neurofibromas uniquely possess Verocay bodies
. Schwannomas are always centrally located within the nerve
. Neurofibromas exclusively affect cranial nerves

Correct Answer & Explanation

. Neurofibromas incorporate nerve fascicles throughout the tumor substance

Explanation

Neurofibromas grow intrinsically within the nerve, intertwining with and separating the nerve fascicles, making nerve-sparing resection difficult. Schwannomas grow eccentrically and push the fascicles aside beneath a true capsule.

Question 69

Topic: Soft Tissue Tumors & Metastasis

A 35-year-old female presents with a growing mass in her popliteal fossa. Histology demonstrates a variable mix of Schwann cells, fibroblasts, and perineurial cells, with mast cells scattered among spindle cells with wavy nuclei. What is the most likely diagnosis?

. Neurofibroma
. Schwannoma
. MPNST
. Synovial sarcoma
. Fibroma of tendon sheath

Correct Answer & Explanation

. Neurofibroma

Explanation

The presence of a heterogeneous cell population (Schwann cells, fibroblasts, mast cells) with wavy, "buckled" nuclei is the classic histologic description of a neurofibroma. Schwannomas are more homogenous.

Question 70

Topic: Soft Tissue Tumors & Metastasis

The "target sign" seen on T2-weighted MRI of a schwannoma corresponds histologically to which of the following spatial arrangements?

. Central dense Antoni A tissue and peripheral myxoid Antoni B tissue
. Central necrosis and peripheral hypercellularity
. Central hemorrhage and peripheral edema
. Central calcification and peripheral fat deposition
. Central Antoni B tissue and peripheral Antoni A tissue

Correct Answer & Explanation

. Central dense Antoni A tissue and peripheral myxoid Antoni B tissue

Explanation

The T2 target sign represents a central area of low signal intensity (highly cellular Antoni A tissue with dense collagen) surrounded by a peripheral rim of high signal intensity (myxoid, hypocellular Antoni B tissue).

Question 71

Topic: Soft Tissue Tumors & Metastasis
Which of the following diagnostic criteria is sufficient to establish a definitive clinical diagnosis of Neurofibromatosis Type 2 (NF2)?
. Bilateral vestibular schwannomas on MRI
. Presence of an optic pathway glioma
. Six or more café-au-lait macules
. Axillary or inguinal freckling
. Congenital pseudarthrosis of the tibia

Correct Answer & Explanation

. Bilateral vestibular schwannomas on MRI

Explanation

Bilateral vestibular schwannomas are the hallmark of NF2 and are sufficient alone to make the diagnosis. The other options listed (optic glioma, café-au-lait spots, freckling, tibial pseudarthrosis) are diagnostic criteria for NF1.

Question 72

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 73

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 74

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 75

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 76

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 77

Topic: Soft Tissue Tumors & Metastasis

During physical examination, a plexiform neurofibroma is classically described as feeling like which of the following?

. A firm, immobile bony exostosis
. A pulsatile, compressible mass
. A "bag of worms"
. A fluctuant fluid-filled cyst
. A hard, painless subcutaneous nodule

Correct Answer & Explanation

. A "bag of worms"

Explanation

Plexiform neurofibromas involve multiple fascicles of a nerve and its branches, creating a complex, irregular mass. On palpation, this is classically described as feeling like a "bag of worms."

Question 78

Topic: Soft Tissue Tumors & Metastasis

When utilizing immunohistochemistry to differentiate peripheral nerve sheath tumors from other soft tissue masses, which marker is strongly and uniformly positive in schwannomas?

. Desmin
. Smooth Muscle Actin (SMA)
. S-100
. CD34
. Cytokeratin

Correct Answer & Explanation

. S-100

Explanation

Schwannomas show strong and uniform positivity for S-100 protein due to their neural crest origin. Neurofibromas also stain for S-100, but typically in a more patchy and variable distribution.

Question 79

Topic: Soft Tissue Tumors & Metastasis

Which of the following histological features best distinguishes a neurofibroma from a schwannoma?

. Neurofibromas are encapsulated; schwannomas are unencapsulated
. Neurofibromas contain primarily Antoni A areas
. Neurofibromas have scattered nerve fibers intermixed within the tumor
. Neurofibromas exclusively contain Verocay bodies
. Neurofibromas exhibit a strong, uniform S-100 positivity

Correct Answer & Explanation

. Neurofibromas have scattered nerve fibers intermixed within the tumor

Explanation

Neurofibromas grow interstitially among nerve fascicles, incorporating nerve fibers throughout the tumor matrix. Schwannomas are encapsulated and push nerve fibers to the periphery.

Question 80

Topic: Soft Tissue Tumors & Metastasis

A patient presents with multiple schwannomas without vestibular nerve involvement. Genetic testing for Schwannomatosis is most likely to reveal a mutation in which of the following genes?

. Neurofibromin (NF1)
. Merlin (NF2)
. SMARCB1 or LZTR1
. PTEN
. APC

Correct Answer & Explanation

. SMARCB1 or LZTR1

Explanation

Schwannomatosis is a distinct clinical entity from NF1 and NF2, characterized by multiple schwannomas without bilateral vestibular involvement. It is genetically linked to mutations in the SMARCB1 (INI1) and LZTR1 genes.

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