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10. Pathology and Oncology MCQs

Practice Set 91 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 1801

Topic: 10. Pathology and Oncology
A 15-year-old girl with a midshaft fibular lesion has histologic findings consistent with Ewing sarcoma. Following induction chemotherapy, local control typically consists of
. radiation therapy only.
. curettage and bone grafting.
. wide resection.
. below-knee amputation.
. observation.

Correct Answer & Explanation

. wide resection.

Explanation

The current treatment regimen for Ewing sarcoma typically involves induction chemotherapy followed by local control and further chemotherapy. Local control consists of surgery only, radiation therapy only, or a combination of the two. In bones that are easily resectable (expendable) with wide margins, surgery is usually recommended.

Question 1802

Topic: 10. Pathology and Oncology
Figures 83a through 83c are the radiograph and MRI scans of a 16-year-old girl who had posterior knee pain after a dance recital 3 weeks ago; the pain resolved 1 week ago with ibuprofen use. What is the appropriate treatment for this patient?
. Biopsy and resection of lesion
. Observation and serial radiographs
. Tc-99 whole-body bone scan and fine-cut CT scan
. Evaluation by a pediatric oncologist

Correct Answer & Explanation

. Observation and serial radiographs

Explanation

The images reveal a small reactive-type lesion in the posteromedial aspect of the distal femur consistent with an avulsive cortical irregularity (cortical desmoid or tug lesion). Proper treatment involves recognition of this benign disorder without further work-up.

Question 1803

Topic: 10. Pathology and Oncology
A 20-year-old man has a large soft-tissue mass behind his knee. MRI scans are shown in Figures 10a through 10c. Figure 10d shows a clinical photograph of his chest. The patient’s condition is most likely a result of a defect in what gene?
. NF1
. EWS
. EXT1
. P53
. Rb

Correct Answer & Explanation

. NF1

Explanation

DISCUSSION: The patient has a plexiform neurofibroma and multiple café-au-lait spots, all characteristic of von Recklinghausen’s neurofibromatosis. This disease has been linked to a defect of the gene NF1 on chromosome 17. EWS is one of the genes associated with the 11;22 translocation found in Ewing’s sarcoma and several other sarcomas. EXT1 is the most common gene affecting patients with multiple hereditary exostosis. P53 and Rb are tumor suppressor genes whose inactivation has been associated with tumors in conditions such as Li-Fraumeni and retinoblastoma, respectively.

Question 1804

Topic: 10. Pathology and Oncology
A 60-year-old woman with a history of breast cancer has progressive paraparesis. The MRI scan is shown in Figure 28. What form of management is most likely to restore or maintain ambulation?
. Radiation therapy and a thoracolumbosacral orthosis
. Laminectomy alone
. Laminectomy and radiation therapy
. Laminectomy and posterior fusion
. Anterior decompression and stabilization

Correct Answer & Explanation

. Anterior decompression and stabilization

Explanation

DISCUSSION: Surgical decompression and stabilization have been shown to be the most effective means of improving neurologic function. Decompression is most reliably done from the side of the compression, which is anterior in this patient.

Question 1805

Topic: Bone Tumors
Initial management of a pathologic fracture of the humerus secondary to a unicameral bone cyst should include
. open curettage and bone grafting.
. intralesional steroid injection.
. percutaneous grafting with a bone graft substitute.
. immobilization until the fracture heals.
. MRI.

Correct Answer & Explanation

. immobilization until the fracture heals.

Explanation

DISCUSSION: Most pathologic humeral fractures secondary to a unicameral bone cyst are minimally displaced and should be immobilized and allowed to heal. Persistent and/or progressive lesions may require treatment. Various treatments of unicameral bone cysts have been described. Acceptable treatment options include curettage and bone grafting, intralesional steroid injection, and percutaneous grafting with bone graft substitutes. MRI is not indicated when the diagnosis of unicameral bone cyst is known. REFERENCES: Wilkins RM: Unicameral bone cysts. J Am Acad Orthop Surg 2000;8:217-224. Bensahel H, Jehanno P, Desgrippes Y, Pennecot GF: Solitary bone cyst: Controversies and treatment. J Pediatr Orthop B 1998;7:257-261.

Question 1806

Topic: 10. Pathology and Oncology
A 12-year-old girl has had increasing left knee pain for the past 3 months. A radiograph is shown in Figure 75a, and low- and high-power photomicrographs are shown in Figures 75b and 75c. What is the most appropriate treatment?
. Chemotherapy alone
. Surgery alone
. Radiation therapy alone
. Chemotherapy and surgery
. Radiation therapy and surgery

Correct Answer & Explanation

. Chemotherapy and surgery

Explanation

DISCUSSION: The radiograph reveals an aggressive purely lytic lesion of the distal femoral metaphysis. There is no apparent matrix mineralization or periosteal reaction. The photomicrographs show a malignant spindle cell neoplasm in a storiform pattern. Based on these findings, the diagnosis is malignant fibrous histiocytoma of bone. At most institutions, patients with this tumor are treated similar to patients with osteosarcoma with multi-agent chemotherapy and surgery with wide margins (resection or amputation). REFERENCES: Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 203-209. Papagelopoulos PJ, Galanis EC, Sim FH, et al: Clinicopathological features, diagnosis, and treatment of malignant fibrous histiocytoma of bone. Orthopedics 2000;23:59-65.

Question 1807

Topic: 10. Pathology and Oncology
A 37-year-old woman has had intermittent paresthesias and numbness in the plantar foot for the past 6 months. She reports that the symptoms are worse with activity, and the paresthesias are beginning to awaken her at night. MRI scans are shown in Figures 6a and 6b. What is the most likely diagnosis?
. Lipoma
. Giant cell tumor of the tendon sheath
. Synovial sarcoma
. Metastatic adenocarcinoma
. Ganglion cyst

Correct Answer & Explanation

. Ganglion cyst

Explanation

DISCUSSION: The symptoms are consistent with tarsal tunnel syndrome. Ganglion cysts are a well-known cause of tarsal tunnel syndrome. The MRI scans show a high intensity, well-circumscribed mass in the tarsal tunnel that is consistent with a fluid-filled cyst. Patients usually respond well to excision of the ganglion and resolution of the tarsal tunnel symptoms. The surrounding fat is a different signal intensity on the MRI scans, which rules out a lipoma. Synovial cell sarcoma has a heterogeneous appearance on an MRI scan. Metastatic tumors are most commonly found in the osseous structures of the foot, not the soft tissues. REFERENCES: Rozbruch SR, Chang V, Bohne WH, et al: Ganglion cysts of the lower extremity: An analysis of 54 cases and review of the literature. Orthopedics 1998;21:141-148. Llauger J, Palmer J, Monill JM, et al: MR imaging of benign soft-tissue masses of the foot and ankle. Radiographics 1998;18:1481-1498. Takakura Y, Kitada C, Sugimoto K, et al: Tarsal tunnel syndrome: Causes and results of operative treatment. J Bone Joint Surg Br 1991;73:125-128.

Question 1808

Topic: 10. Pathology and Oncology
A 17-year-old boy has had a mass in his right thigh for the past 6 months. He denies any history of trauma. Examination reveals that the mass is painless and firm. A radiograph and axial MRI scan are shown in Figures 49a and 49b. What is the most likely diagnosis?
. Osteochondroma
. Osteosarcoma
. Periosteal chondroma
. Ewing’s sarcoma of bone
. Chondroblastoma

Correct Answer & Explanation

. Osteochondroma

Explanation

DISCUSSION: Osteochondroma typically occurs as a bony projection or a sessile growth on the bone, and there can be flaring of the metaphysis. The radiograph shows continuity from the adjacent cancellous bone into the lesion itself. There is no soft-tissue mass or bone destruction to suggest osteosarcoma or Ewing’s sarcoma. Periosteal chondroma has a scalloped out radiographic appearance. Chondroblastoma typically is an epiphyseal-based lesion. REFERENCE: Wold LA, et al: Osteochondroma: Atlas of Orthopaedic Pathology. Philadelphia, PA, WB Saunders, 1990, p 50.

Question 1809

Topic: 10. Pathology and Oncology

Which of the following techniques is most commonly used to classify tissue type in soft-tissue tumors?

. karyotyping
. flow cytometry
. transmission electron microscopy
. immunohistochemistry staining
. scanning electron microscopy

Correct Answer & Explanation

. karyotyping

Explanation

Microscopy allows for visualization of the cells; however, special staining is required for identification and classification of specific cells. Karyotyping refers only to the number and structure of chromosomes in a cell. Flow cytometry is used to determine the amount of DNA in a cell, and are predictive for the degree of malignancy. Staining methods are currently the most commonly used method to classify tissue type.

Question 1810

Topic: 10. Pathology and Oncology

Figures 38a and 38b are the MRI scans of a 28-year-old man who reports progressively worsening severe back pain for the past 3 months. He denies fevers, chills, weakness, or neurologic dysfunction. Examination reveals tenderness to palpation over the lumbar spine but normal neurologic findings. Laboratory studies reveal an elevated erythrocyte sedimentation rate and C-reactive protein; blood cultures are positive for methicillin-sensitive Staphylococcus aureus. In addition to intravenous antibiotics, what is the next step in management? Review Topic

. CT-guided biopsy
. Application of lumbar orthosis
. Repeat MRI within 48 hours
. Anterior lumbar debridement and fusion
. Posterior lumbar debridement and fusion

Correct Answer & Explanation

. CT-guided biopsy

Explanation

The patient's symptoms and MRI findings are consistent with osteomyelitis and diskitis at L3-4 with a paraspinal fluid collection. Cultures confirm bacterial involvement. Given that finding, a biopsy of the level is unnecessary. Surgical treatment for infection is not indicated given the lack of neurologic deficit. Nonsurgical management is the best option, including both intravenous antibiotics and an external lumbar orthosis. A repeat MRI scan within a short duration would not impact clinical care. More important is close clinical follow-up to confirm response to treatment and identify any potential neurologic deficits that may develop.

Question 1811

Topic: 10. Pathology and Oncology
Chemotherapy is routinely included in the treatment of which of the following soft-tissue sarcomas?
. Angiosarcoma
. Malignant fibrous histiocytoma
. Liposarcoma
. Rhabdomyosarcoma
. Clear cell sarcoma

Correct Answer & Explanation

. Rhabdomyosarcoma

Explanation

DISCUSSION: Most soft-tissue sarcomas are treated with a combination of radiation therapy and wide resection. Rhabdomyosarcomas are an exception, where chemotherapy is included in all treatment plans. Chemotherapy for other soft-tissue sarcomas is controversial.

Question 1812

Topic: 10. Pathology and Oncology
What is the preferred treatment of a patient with breast cancer and a pathologic fracture of the clavicle in her dominant arm?
. Surgical stabilization
. Sling
. Physical therapy
. Wide resection
. Radiofrequency ablation

Correct Answer & Explanation

. Sling

Explanation

Closed management should be attempted for upper extremity pathologic fractures, particularly the clavicle. If nonunion or pain persists, surgery may be indicated. Radiofrequency ablation is not indicated for subcutaneous bones. Early motion is likely to cause increased pain and disability.

Question 1813

Topic: 10. Pathology and Oncology
Figures 19a and 19b show the AP and lateral radiographs of an 18-year-old man who has had knee pain for 3 months. Figure 19c shows a histopathologic photomicrograph of the biopsy specimen. Which of the following factors is most likely to affect his survival?
. The decision to proceed with limb-sparing surgery instead of amputation
. The presence of a mutated p53 gene
. Pulmonary nodules detected on a CT scan
. Location of the tumor
. Tumor necrosis of 99% following preoperative chemotherapy

Correct Answer & Explanation

. Pulmonary nodules detected on a CT scan

Explanation

The presence of metastatic disease at diagnosis is the most significant prognostic factor in a patient with osteosarcoma. Limb-sparing surgery, when compared with amputation, is not noted to be associated with any difference in the rate of survival. The presence of a mutated p53 gene has been noted in a minority of patients with osteosarcoma; however, the prognostic importance on an individual basis is unclear.

Question 1814

Topic: 10. Pathology and Oncology
Which of the following conditions is transmitted by an autosomal dominant trait?
. Multiple hereditary exostosis
. Ollier’s disease
. Li-Fraumeni syndrome
. Maffucci’s syndrome
. Retinoblastoma

Correct Answer & Explanation

. Multiple hereditary exostosis

Explanation

Multiple hereditary exostosis is transmitted by an autosomal dominant trait. Li-Fraumeni syndrome and retinoblastoma are associated with autosomal dominant mutations (though retinoblastoma can be sporadic). No genetic predisposition to Ollier’s disease or Maffucci’s syndrome has been identified.

Question 1815

Topic: 10. Pathology and Oncology

A 45-year-old agricultural worker who resides in the San Joaquin Valley of California presents with a 6-month history of right knee pain and swelling. Radiographs show a lytic lesion in the distal femur. Biopsy of the lesion reveals thick-walled spherules containing endospores. Which of the following is the most likely causative organism?

. Blastomyces dermatitidis
. Coccidioides immitis
. Sporothrix schenckii
. Histoplasma capsulatum
. Cryptococcus neoformans

Correct Answer & Explanation

. Blastomyces dermatitidis

Explanation

Coccidioidomycosis ('Valley Fever') is caused by Coccidioides immitis or C. posadasii, which are endemic to the arid regions of the Southwestern US, including the San Joaquin Valley. The classic histological hallmark of Coccidioides is the presence of thick-walled spherules containing endospores.

Question 1816

Topic: 10. Pathology and Oncology

A 62-year-old male with a 30-year history of chronic osteomyelitis of the tibia secondary to an open fracture presents with a newly enlarging, fungating, exophytic mass arising from his chronic draining sinus tract. What is the most likely pathological diagnosis of this mass?

. Osteosarcoma
. Malignant fibrous histiocytoma
. Squamous cell carcinoma
. Basal cell carcinoma
. Chondrosarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

A malignant transformation arising within a chronic osteomyelitis sinus tract or chronic burn scar is known as a Marjolin's ulcer. Histologically, the vast majority of these lesions are squamous cell carcinomas (SCC).

Question 1817

Topic: 10. Pathology and Oncology
Mutations of what gene are associated with subsequent development of osteosarcoma?
. NF1 (neurofibromatosis)
. Rb (retinoblastoma)
. VEGF (vascular endothelial growth factor)
. E-Cadherin
. EWS-FLI1 (11,22 translocation)

Correct Answer & Explanation

. Rb (retinoblastoma)

Explanation

The mutation of the retinoblastoma gene has been associated with an increased prevalence of osteosarcoma. The mutation resulting in EWS-FLI1 is associated with Ewing’s sarcoma. The other mutations are associated with tumor formation and proliferation but not necessarily with osteosarcoma formation.

Question 1818

Topic: 10. Pathology and Oncology

Radiotherapy for palliative pain control as the risk for pathological fracture is very small

. Open incisional biopsy
. Chemotherapy and surgical stabilization with intramedullary nailing of the tibia
. Radiotherapy and surgical stabilization with intramedullary nailing of the tibia

Correct Answer & Explanation

. Open incisional biopsy

Explanation

Treatment for musculoskeletal oncology depends on a correct tissue diagnosis, which in this patient requires an open incisional biopsy. Despite the concern that this lesion may represent a metastasis from lung carcinoma, without tissue diagnosis, treatment cannot ensue. Regarding concerns for pathologic fracture, this patient would be best managed with no weight bearing until a diagnosis can be determined. If this lesion is a sarcoma, then despite the patient's pain and risk of pathologic fracture, neo-adjuvant chemotherapy and wide surgical resection will be needed for the best chance at local control and patient survival. While intramedullary nailing of the tibia and sending canal reamings to pathology may either appear appropriate or be performed atsome centers, this procedure may contaminate the entire bone with tumor and make limb salvage nearly impossible if this is a sarcoma. If the incisional biopsy shows carcinoma, then intramedullary nailing with adjuvant radiotherapy would be completely appropriate.

Question 1819

Topic: 10. Pathology and Oncology
A 10-year-old girl has a knee pain for the past 2 months. She also has a low-grade fever of 101.3 degrees F (38.5 degrees C). Laboratory studies show a WBC count of 12,100/mm3 and an erythrocyte sedimentation rate of 58/h. A biopsy specimen of a lesion in the distal femoral metaphysis is shown in Figure 38. What is the most appropriate treatment?
. Radiation therapy alone
. Intralesional steroid injection
. Chemotherapy followed by surgery or radiation therapy
. Debridement and antibiotics
. Debridement alone

Correct Answer & Explanation

. Debridement and antibiotics

Explanation

The clinical presentation of this patient is consistent with both acute osteomyelitis and Ewing’s sarcoma. Both entities can be noted in the distal femoral metaphysis although Ewing’s sarcoma is classically noted in the diaphysis. The histology reveals a mixed inflammatory cell infiltrate with neutrophils, plasma cells, lymphocytes, and histiocytes. Ewing’s sarcoma would be a uniform population of small round blue cells without an inflammatory component. Eosinophilic granuloma (EG) is characterized by Langerhans histiocytes and eosinophils. Treatment of EG often consists of an intralesional steroid injection. Treatment of acute osteomyelitis includes surgical debridement and antibiotics.

Question 1820

Topic: 10. Pathology and Oncology
The lesion seen in Figure 4 is most likely the result of metastases from what solid organ?
. Breast
. Lung
. Thyroid
. Prostate
. Liver

Correct Answer & Explanation

. Lung

Explanation

The primary carcinoma most likely to metastasize distal to the elbow and knees is lung carcinoma. Renal cell carcinoma can also metastasize to distal sites. Most metastatic bone disease occurs in the vertebral bodies, pelvis, and proximal long bones.

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