Menu

10. Pathology and Oncology MCQs

Practice Set 188 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 3741

Topic: 10. Pathology and Oncology

A 28-year-old male with known Neurofibromatosis type 1 presents with rapid enlargement and new-onset severe rest pain in a long-standing thigh mass. What is the most appropriate next step in management?

. Incisional biopsy or core needle biopsy
. Marginal excision of the mass
. Reassurance and repeat MRI in 6 months
. Immediate initiation of radiation therapy
. Wide en bloc resection without prior biopsy

Correct Answer & Explanation

. Incisional biopsy or core needle biopsy

Explanation

Rapid growth and severe pain in a pre-existing plexiform neurofibroma in an NF1 patient strongly suggest malignant transformation to a Malignant Peripheral Nerve Sheath Tumor (MPNST). A biopsy is required to confirm the diagnosis before planning definitive wide resection.

Question 3742

Topic: 10. Pathology and Oncology

A surgical pathology report for a resected peripheral nerve tumor describes unencapsulated spindle cells intermingled with nerve fibers and thick, wavy collagen bundles resembling "shredded carrots." Which of the following is most accurate regarding this lesion?

. It can usually be shelled out without nerve injury.
. It has a high propensity to be associated with bilateral vestibular schwannomas.
. Surgical excision inherently requires sacrificing the involved nerve.
. The tumor arises exclusively from the myelin sheath.
. It lacks S-100 immunoreactivity completely.

Correct Answer & Explanation

. Surgical excision inherently requires sacrificing the involved nerve.

Explanation

The histology describes a neurofibroma. Unlike schwannomas, neurofibromas are intimately intermingled with the nerve fascicles, meaning complete surgical excision typically requires sacrificing the involved nerve segment.

Question 3743

Topic: 10. Pathology and Oncology

A 30-year-old female presents with bilateral hearing loss, balance issues, and a palpable mass on her left ulnar nerve. MRI of the brain reveals bilateral vestibular tumors. The mutated gene in this syndrome encodes for which of the following proteins?

. Neurofibromin
. Merlin
. P53
. Rb
. Dystrophin

Correct Answer & Explanation

. Merlin

Explanation

The patient has Neurofibromatosis type 2, characterized by bilateral vestibular schwannomas. NF2 is caused by a mutation on chromosome 22, which encodes the tumor suppressor protein merlin (also known as schwannomin).

Question 3744

Topic: 10. Pathology and Oncology

On T2-weighted MRI, a benign peripheral nerve sheath tumor exhibits a "target sign" with peripheral hyperintensity and central hypointensity. The lesion is eccentric to the nerve. Which of the following immunohistochemical markers will be strongly and diffusely positive?

. SMA
. Desmin
. S-100
. CD34
. EMA

Correct Answer & Explanation

. S-100

Explanation

The MRI "target sign" and eccentric location are classic for a schwannoma. Schwannomas are of neural crest origin and stain strongly and diffusely positive for S-100 protein.

Question 3745

Topic: 10. Pathology and Oncology

A 42-year-old patient with NF-1 is diagnosed with a high-grade Malignant Peripheral Nerve Sheath Tumor (MPNST) of the sciatic nerve. Which of the following factors carries the worst prognostic implication for overall survival in this patient?

. Tumor size less than 5 cm
. S-100 positivity on immunohistochemistry
. Presence of the NF-1 mutation
. Complete surgical margins
. Distal location in the extremity

Correct Answer & Explanation

. Presence of the NF-1 mutation

Explanation

In patients with MPNST, the presence of an underlying NF-1 diagnosis is associated with a significantly worse prognosis and decreased overall survival compared to sporadic cases. Large tumor size and incomplete surgical margins also confer a poor prognosis.

Question 3746

Topic: 10. Pathology and Oncology

During microscopic examination of an enucleated peripheral nerve mass, the pathologist notes palisading nuclei surrounding eosinophilic, anuclear zones of cellular processes. What is the eponym for this specific histologic structure?

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

Correct Answer & Explanation

. Verocay bodies

Explanation

Verocay bodies are formed by palisading nuclei surrounding anuclear zones and are characteristic of Antoni A areas in schwannomas. This is a classic distinguishing histological feature of this benign nerve sheath tumor.

Question 3747

Topic: 10. Pathology and Oncology

A 55-year-old male incidentally discovers a 2 cm painless, mobile mass in the medial aspect of his arm. Ultrasound demonstrates a well-defined, hypoechoic lesion eccentric to the ulnar nerve with posterior acoustic enhancement. Neurological exam is normal. What is the most appropriate initial management?

. Immediate marginal excision
. Wide local excision with nerve graft
. Observation and clinical follow-up
. Core needle biopsy
. Neoadjuvant radiation therapy

Correct Answer & Explanation

. Observation and clinical follow-up

Explanation

The clinical and sonographic findings are highly suggestive of an asymptomatic benign schwannoma. Because malignant transformation is exceptionally rare and surgery carries a risk of iatrogenic nerve injury, observation is the most appropriate initial management.

Question 3748

Topic: 10. Pathology and Oncology

A mass excised from a 12-year-old boy's brachial plexus reveals enlarged, tortuous nerve fascicles grossly resembling a "bag of worms." Histologically, the lesion expands the nerve fascicles. Which of the following is true regarding this tumor type?

. It is an encapsulated tumor that does not invade the epineurium.
. It is rarely associated with Neurofibromatosis Type 1.
. It has a 5-10% lifetime risk of malignant transformation.
. It primarily consists of Antoni A and Antoni B regions.
. Surgical excision is curative with almost no risk of recurrence.

Correct Answer & Explanation

. It has a 5-10% lifetime risk of malignant transformation.

Explanation

A "bag of worms" appearance describes a plexiform neurofibroma, which is pathognomonic for NF-1. These tumors carry an approximately 5-10% lifetime risk of transforming into a Malignant Peripheral Nerve Sheath Tumor (MPNST).

Question 3749

Topic: 10. Pathology and Oncology

Malignant Peripheral Nerve Sheath Tumors (MPNSTs) most commonly arise from which of the following cellular components of the peripheral nerve?

. Fibroblasts
. Perineurial cells
. Schwann cells
. Axonal neurons
. Endothelial cells

Correct Answer & Explanation

. Schwann cells

Explanation

MPNSTs are malignant sarcomas of neural crest origin that primarily differentiate toward, and arise from, Schwann cells. They often occur in the setting of pre-existing plexiform neurofibromas in NF-1 patients.

Question 3750

Topic: 10. Pathology and Oncology

A surgeon is performing an excision of a confirmed median nerve schwannoma. To minimize the risk of permanent neurologic deficit, the longitudinal incision through the epineurium should be made in which location?

. Directly over the most vascular portion of the tumor
. At the site with the highest density of nerve fascicles
. In an area devoid of functional nerve fascicles (safe zone)
. Circumferentially around the entire nerve
. Transversely across the proximal pole of the tumor

Correct Answer & Explanation

. In an area devoid of functional nerve fascicles (safe zone)

Explanation

Excision of a schwannoma requires a longitudinal epineurotomy in a "safe zone" devoid of traversing nerve fascicles. Careful microscopic dissection allows the encapsulated tumor to be shelled out while preserving functional motor and sensory fascicles.

Question 3751

Topic: 10. Pathology and Oncology

A 40-year-old male without systemic disease presents with a solitary, slow-growing, mildly tender cutaneous mass on his trunk. Biopsy reveals a well-circumscribed but unencapsulated proliferation of S-100 positive spindle cells with wavy nuclei in a collagenous stroma. No other lesions are present. What is the risk of malignant transformation for this specific lesion?

. Less than 1%
. 5 to 10%
. 20 to 30%
. 50%
. Virtually 100%

Correct Answer & Explanation

. Less than 1%

Explanation

The patient has a sporadic, localized cutaneous neurofibroma. Unlike plexiform neurofibromas associated with NF-1, solitary cutaneous neurofibromas have virtually zero (less than 1%) risk of malignant transformation.

Question 3752

Topic: 10. Pathology and Oncology

A 35-year-old female with known NF-1 presents for routine MRI surveillance of a massive sciatic plexiform neurofibroma. Which of the following MRI findings would be most highly suspicious for malignant transformation to an MPNST?

. Target sign on T2-weighted imaging
. Fascicular sign on T1-weighted imaging
. Presence of a split-fat sign
. Perilesional edema and ill-defined margins
. Location centrally within the nerve bundle

Correct Answer & Explanation

. Perilesional edema and ill-defined margins

Explanation

Findings suggesting malignant transformation include rapid growth, perilesional edema, ill-defined margins (suggesting local invasion), and cystic or necrotic changes. The "target sign" and "split-fat sign" are typical of benign peripheral nerve sheath tumors.

Question 3753

Topic: 10. Pathology and Oncology

In addition to spindle-shaped Schwann cells and fibroblasts, which inflammatory cell type is frequently abundant in the stroma of a neurofibroma and is thought to play a role in tumor growth and pain generation?

. Eosinophils
. Mast cells
. Neutrophils
. Plasma cells
. Multinucleated giant cells

Correct Answer & Explanation

. Mast cells

Explanation

Mast cells are characteristically abundant in the myxoid stroma of neurofibromas. They are believed to secrete mediators that promote tumor angiogenesis, fibroblast proliferation, and the typical pain or pruritus associated with these tumors.

Question 3754

Topic: 10. Pathology and Oncology

A 65-year-old female undergoes resection of a deep seated, long-standing retroperitoneal schwannoma. The pathology report notes degenerative changes including cyst formation, calcification, and nuclear atypia without mitotic figures. This histologic pattern is commonly referred to as:

. Malignant transformation
. Ancient schwannoma
. Plexiform schwannoma
. Cellular schwannoma
. Melanotic schwannoma

Correct Answer & Explanation

. Ancient schwannoma

Explanation

"Ancient schwannoma" is a benign variant characterized by degenerative changes such as cyst formation, calcification, hemorrhage, and marked nuclear atypia. The absence of mitotic figures and necrosis differentiates it from a true malignancy.

Question 3755

Topic: 10. Pathology and Oncology

A 45-year-old female presents with a slow-growing, painful mass in her volar forearm. Excisional biopsy reveals an encapsulated tumor with alternating hypercellular and hypocellular areas. The hypercellular areas feature palisading nuclei around fibrillary processes. What is the most likely diagnosis?

. Neurofibroma
. Schwannoma
. Malignant Peripheral Nerve Sheath Tumor (MPNST)
. Desmoid Tumor
. Synovial Sarcoma

Correct Answer & Explanation

. Schwannoma

Explanation

The description highlights Antoni A (hypercellular with Verocay bodies) and Antoni B (hypocellular) areas, classic for a Schwannoma. Schwannomas are encapsulated and eccentric to the nerve fascicles.

Question 3756

Topic: 10. Pathology and Oncology

When evaluating a peripheral nerve sheath tumor using MRI, the "target sign" is frequently observed on T2-weighted images. What histologic features correspond to this radiographic appearance?

. Central hemorrhage and peripheral necrosis
. Central calcification and peripheral edema
. Central dense fibrous tissue and a peripheral myxoid stroma
. Central cystic degeneration and a peripheral cellular rim
. Central hemosiderin deposition and peripheral hypervascularity

Correct Answer & Explanation

. Central dense fibrous tissue and a peripheral myxoid stroma

Explanation

The T2 target sign reflects a low-signal center of dense fibrous collagenous tissue and a high-signal periphery of water-rich myxoid tissue. It is commonly seen in both neurofibromas and schwannomas.

Question 3757

Topic: 10. Pathology and Oncology

A 30-year-old male with a known genetic disorder presents with a massive, tortuous, "bag of worms" soft tissue mass along his sciatic nerve. He complains of new-onset severe pain and rapidly progressive foot drop. What is the most likely underlying genetic mutation?

. Mutation of the NF1 gene on chromosome 17 encoding neurofibromin
. Mutation of the NF2 gene on chromosome 22 encoding merlin
. Mutation of the SMARCB1 gene on chromosome 22
. Mutation of the APC gene on chromosome 5
. Translocation t(X;18) involving the SYT and SSX genes

Correct Answer & Explanation

. Mutation of the NF1 gene on chromosome 17 encoding neurofibromin

Explanation

The patient has a plexiform neurofibroma ("bag of worms"), which is pathognomonic for Neurofibromatosis type 1 (NF1). The new pain and motor deficit suggest malignant transformation to MPNST.

Question 3758

Topic: 10. Pathology and Oncology

A surgeon is planning the excision of a symptomatic solitary peripheral nerve sheath tumor located in the median nerve. Preoperative imaging suggests a schwannoma. Which of the following describes the most appropriate surgical approach?

. En bloc resection of the tumor with a 2-cm margin of healthy nerve
. Epineurotomy with marginal enucleation of the tumor, sparing the fascicles
. Intralesional curettage followed by phenol application
. Nerve resection with immediate cable grafting
. Primary radiation therapy without surgical excision

Correct Answer & Explanation

. Epineurotomy with marginal enucleation of the tumor, sparing the fascicles

Explanation

Schwannomas grow eccentrically and displace nerve fascicles to the periphery. They can typically be treated with longitudinal epineurotomy and careful marginal enucleation, preserving nerve function.

Question 3759

Topic: 10. Pathology and Oncology

Histologic evaluation of a resected peripheral nerve sheath tumor demonstrates unencapsulated proliferation of spindle cells, an abundant myxoid matrix, interwoven nerve fascicles, and "shredded carrot" collagen bundles. Which of the following is true regarding this lesion?

. It strongly uniformly expresses S-100 and SOX10 markers.
. It can usually be enucleated without causing neurologic deficits.
. It is defined by its biphasic Antoni A and B histologic patterns.
. Surgical resection inevitably requires sacrifice of the involved nerve fascicles.
. Malignant transformation occurs in >50% of solitary sporadic lesions.

Correct Answer & Explanation

. Surgical resection inevitably requires sacrifice of the involved nerve fascicles.

Explanation

The histology describes a neurofibroma. Unlike schwannomas, neurofibromas grow intrinsically among the nerve fascicles, meaning surgical resection typically requires sacrifice of the involved nerve segment.

Question 3760

Topic: 10. Pathology and Oncology

A patient with bilateral vestibular schwannomas and multiple peripheral nerve tumors is being evaluated. Which of the following proteins is deficient or defective in this patient's underlying syndrome?

. Neurofibromin
. Merlin (Schwannomin)
. P53
. Dystrophin
. Fibrillin-1

Correct Answer & Explanation

. Merlin (Schwannomin)

Explanation

Bilateral vestibular schwannomas are the hallmark of Neurofibromatosis type 2 (NF2). This disorder is caused by a mutation in the NF2 gene on chromosome 22q12, which encodes the protein merlin.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page