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 2041
Topic: 10. Pathology and Oncology
A 20-year-old man has a symptomatic lesion of fibrous dysplasia in the femoral neck. Management should consist of
Correct Answer & Explanation
. curettage, cortical strutting, and internal fixation.
Explanation
Fibrous dysplasia in the femoral neck frequently warrants treatment because of the risk of pathologic fracture. Cortical strut grafts reduce the risk of local recurrence compared with cancellous bone grafting. Because of the consequences associated with fracture in this location, prophylactic fixation is recommended. Radiation therapy and chemotherapy are not used for this benign condition. Simon M, et al: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, pp 197.
Question 2042
Topic: 10. Pathology and Oncology
A 7-year-old boy has a limp with pain and tenderness over the distal right femur. Radiographs are shown in Figures 5a and 5b. Based on these findings, what is the best course of action?
Correct Answer & Explanation
. Biopsy, curettage, and bone grafting
Explanation
The patient has a nonossifying fibroma, and the symptoms suggest that there is significant weakening of the cortex and/or microfracture; therefore, biopsy, curettage, and bone grafting is the treatment of choice. Based on the size of the lesion and the presence of symptoms, observation is likely to result in pathologic fracture. A biopsy will further weaken the bone unless combined with curettage and bone grafting. Radiation therapy is not used in the treatment of nonossifying fibroma and is rarely used in any benign condition affecting skeletally immature individuals. Steroid injection has been used in the treatment of unicameral bone cysts and in Langerhan's cell histiocytosis but not for nonossifying fibroma. Dormans, JP, Pill SG: Fractures through bone cysts: Unicameral bone cysts, aneurysmal bone cysts, fibrous cortical defects, and nonossifying fibromas. Instr Course Lect 2002;51:457-467.
Question 2043
Topic: 10. Pathology and Oncology
A 13-year-old boy has had a painless mass in the arm for the past 2 months. An MRI scan and biopsy specimens are shown in Figures 46a through 46c. What is the most likely diagnosis?
Correct Answer & Explanation
. Nodular fasciitis
Explanation
Nodular fasciitis is a benign soft-tissue lesion that usually arises from the fascia and is often misdiagnosed as a sarcoma. Desmoid tumors (aggressive fibromatosis) are also benign tumors with a greater tendency for local recurrence. Desmoid tumors have more spindle-shaped fibroblasts in an abundant collagenous matrix. Malignant fibrous histiocytoma is a hypercellular pleomorphic sarcoma more commonly found in adults. The histology is not consistant with a fatty tumor.
Question 2044
Topic: 10. Pathology and Oncology
A 10-year-old boy has had wrist pain for the past 3 months. He denies any history of trauma. He reports mild tenderness associated with a palpable mass. A radiograph and biopsy specimens are shown in Figures 52a through 52c. What is the most likely diagnosis?
Correct Answer & Explanation
. Periosteal chondroma
Explanation
The radiograph shows a benign-appearing cortically based lesion eroding the underlying cortex, producing a saucer-shaped defect typical of a periosteal chondroma. The histology shows benign-appearing neoplastic cartilage. Although enchondroma would have the same histologic appearance, radiographs generally show a lesion with a central medullary epicenter. The benign-appearing histology does not support chondrosarcoma. Chondromyxoid fibroma will generally show histologic elements of its fibrous and myxoid components. Chondroblastoma typically demonstrates histologic findings of polyhedral cells separated by a chondroid matrix with pericellular, lattice-like "chicken wire" calcification. Schajowicz F: Tumors and Tumorlike Lesions of Bone: Pathology, Radiology, and Treatment, ed 2. Berlin, Springer-Verlag, 1994, pp 147-151.
Question 2045
Topic: 10. Pathology and Oncology
A 16-year-old girl has had hip pain for 1 year. Approximately 2 months ago she noted the development of a hard mass in the right buttock that has steadily increased in size. She now reports severe pain in the right buttock, with radiation down the leg and numbness involving the right foot and toes. A radiograph is shown in Figure 70a and an axial postcontrast T1-weighted MRI scan is shown in Figure 70b. A biopsy specimen is shown in Figure 70c. The chest CT shows multiple lung metastases. Treatment of this lesion should consist of
Correct Answer & Explanation
. chemotherapy and radiation therapy.
Explanation
Ewing's sarcoma is the second most common primary tumor of bone in children. Depending on the site and extent of disease, chemotherapy, radiation therapy, and surgery are all treatment options. In this patient with extensive pelvic and metastatic disease, chemotherapy and radiation therapy offer the best oncologic control while preserving functional outcome. Gibbs CP Jr, Weber K, Scarborough MT: Malignant bone tumors. Instr Course Lect 2002;51:413-428. Thacker MM, Temple HT, Scully SP: Current treatment for Ewing's sarcoma. Expert Rev Anticancer Ther 2005;5:319-331.
Question 2046
Topic: 10. Pathology and Oncology
An 11-year-old boy sustained an injury to his arm in gym class. He denies prior pain in the arm. Radiographs are shown in Figures 48a and 48b. What is the next most appropriate step in the management of this lesion?
Correct Answer & Explanation
. Allow the fracture to heal with nonsurgical management and serial radiographs
Explanation
This radiolucent lesion with a "fallen leaf sign" is typical for a unicameral bone cyst(UBC). The most appropriate treatment is to allow the fracture to heal with clinical and radiographic observation. Curettage and bone grafting is not the best initial management for UBC. Wide resection is not indicated for UBC. The proximal humerus is the most common site for UBC. While staging studies consisting of MRI, bone scan, and CT of the chest are appropriate for lesions suspected of being malignant, the classical appearance of this UBC is such that this work-up is not necessary initially. Following fracture healing, aspiration and injection of the cyst may be indicated. Dormans JP, Pill SG: Fractures through bone cysts: Unicameral bone cysts, aneurysmal bone cysts, fibrous cortical defects, and nonossifying fibromas. Instr Course Lect 2002;51:457-467.
Question 2047
Topic: 10. Pathology and Oncology
A 10-year-old child reports acute leg pain after wrestling with his brother. AP and lateral radiographs are shown in Figures 21a and 21b. What is the best course of action?
Correct Answer & Explanation
. Biopsy, curettage, and plating
Explanation
The radiographs show an eccentric metaphyseal lesion with a well-defined reactive rim of bone that is consistent with a nonossifying fibroma. Pathologic fractures through benign lesions should be treated as appropriate for the fracture, allowing the fracture to heal. Biopsy is not needed when the radiographic diagnosis is benign. MRI, in the presence of a fracture, is not particularly helpful because of the hematoma. If radiographic findings reveal that the lesion appears aggressive, a biopsy should be performed, obtaining tissue away from the fracture site. Marks KE, Bauer TW: Fibrous tumors of bone. Orthop Clin North Am 1989;20:377.
Question 2048
Topic: 10. Pathology and Oncology
An 8-year-old boy is diagnosed with acute onset cauda equina syndrome. A radiograph, MRI scans, and a biopsy specimen are shown in Figures 57a through 57d. What is the most appropriate treatment?
Correct Answer & Explanation
. Marginal surgical resection
Explanation
The findings are consistent with an aneurysmal bone cyst. The MRI scan demonstrates a lesion involving the posterior elements of the vertebrae with fluid-fluid levels and neural compression. Fibrovascular tissue with multinucleated giant cells surrounding a vascular lake is seen on the histology. The most appropriate treatment is a marginal resection of the involved posterior elements. Although the recurrence rate can be as high as 25% to 30%, wide surgical resection could result in permanent neurologic injury and is not necessary. Aspiration and steroid injection have been advocated but would not relieve the nerve compression in this patient. Radiation therapy and chemotherapy are not indicated. Mankin HJ, Hornicek FJ, Ortiz-Cruz E, et al: Aneurysmal bone cyst: A review of 150 patients. J Clin Oncol 2005;23:6756-6762.
Question 2049
Topic: 10. Pathology and Oncology
An axial T1-weighted MRI scan of the pelvis is shown in Figure 35. Which of the following structures is enclosed by the circle?
Correct Answer & Explanation
. Obturator vessels and nerve
Explanation
The obturator vessels and nerve pass along the lateral pelvic wall along the true pelvic brim (nerve lies anterior to the vessels and lies on the obturator internus muscle) and descend into the obturator groove at the upper portion of the obturator foramen. Higuchi T: Normal anatomy and magnetic resonance appearance of the pelvis, in Takahashi HE, Morita T, Hotta T, et al (eds): Operative Treatment of Pelvic Tumors. Tokyo, Japan, Springer-Verlag, 2003, pp 4-21.
Question 2050
Topic: Bone Tumors
A 40-year-old woman has a symptomatic mass on the anterior aspect of the ankle. She reports no constitutional symptoms. An MRI scan is shown in Figure 12. What is the most likely diagnosis?
Correct Answer & Explanation
. Ganglion
Explanation
The MRI scan reveals a lobular mass that is below the vitamin E tablet marker taped to the skin. This is juxtaposed to the tibialis anterior tendon. It is slightly more enhanced than the surrounding subcutaneous fat and is consistent with a ganglion. Osteosarcoma, aneurysmal bone cyst, or unicameral bone cyst all would demonstrate enhancement or pathology in the bone. This is clearly a well-defined soft-tissue mass. Gouty tophi show low to intermediate signal on T1- and T2-weighted images. Kransdorf MJ, Jelinek JS, Moser RP Jr, et al: Soft tissue masses: Diagnosis using MR imaging. Am J Roentgenol 1989;153:541-547. Wetzel LH, Levine E: Soft-tissue tumors of the foot: Value of MR imaging for specific diagnosis. Am J Roentgenol 1990;155:1025-1030.
Question 2051
Topic: 10. Pathology and Oncology
Figure 2 shows the radiograph of a 72-year-old woman who reports pain after a fall. History includes several years of increasing thigh pain and limb shortening. Management consisting of an extensive work-up for infection reveals normal laboratory studies, a positive bone scan, and a negative hip aspiration. What is the most likely etiology of this complication?
Correct Answer & Explanation
. Loosening of the prosthesis
Explanation
The patient has a midstem periprosthetic fracture, which commonly results in loosening of the prosthesis. Patients who have a large amount of bone loss may require an allograft with the surgical reconstruction. Although the patient reported a fall, her history is also consistent with preexisting loosening of the prosthesis. Chronic infection has been shown in up to 16% of these fractures; however, the patient's work-up revealed no infection.
Question 2052
Topic: 10. Pathology and Oncology
A radiograph, MRI scans, and a biopsy specimen of a 9-year-old boy with thigh pain are shown in Figures 37a through 37d. Management should consist of
Correct Answer & Explanation
. wide resection of the femur and reconstruction.
Explanation
The patient has Ewing's sarcoma. Management options for local tumor control include radiation therapy, resection, or a combination; however, in this patient wide resection is preferred over radiation therapy. Radiation therapy is associated with damage to the growth plate, pathologic fracture, radiation-induced sarcomas, and a local recurrence rate of approximately 10% to 12%. Radiation therapy is used for positive margins, unresectable tumors, or for tumors that have a poor response to chemotherapy. Amputation is not necessary since the tumor is resectable. Chemotherapy has improved overall survival rates to over 60% of patients.
Question 2053
Topic: 10. Pathology and Oncology
Five weeks after undergoing a successful L4-L5 diskectomy, with complete relief of his preoperative sciatica, a 36-year-old man has severe, relentless back and buttock pain. Examination and laboratory studies are unremarkable with the exception of an erythrocyte sedimentation rate (ESR) of 90 mm/h. What is the next most appropriate step in management?
Correct Answer & Explanation
. MRI with gadolinium
Explanation
The patient's history, including the timing and type of symptoms, is typical for postoperative diskitis. The elevated ESR, 5 weeks after surgery, is also consistent with infection; a normal WBC count is not unusual. Management should consist of MRI with gadolinium; if positive, this should be followed by percutaneous biopsy to confirm the organism. Open biopsy may be considered if the percutaneous biopsy is unsuccessful. Anterior debridement and interbody fusion is reserved for the occasional patient that fails to respond to intravenous antibiotics, bed rest, and immobilization. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 257-271.
Question 2054
Topic: Bone Tumors
A 23-year-old man has had right posterolateral knee pain and occasional lateral calf dysesthesias for the past 8 months. A radiograph, CT scan, MRI scans, and a biopsy specimen are shown in Figures 62a through 62e. What is the most likely diagnosis?
Correct Answer & Explanation
. Osteoid osteoma
Explanation
The radiograph shows an eccentric, cortically based lytic lesion in the proximal fibula. The CT and MRI scans confirm that it is well circumscribed and cortically based with significant surrounding edema. The radiographic differential diagnosis would be a Brodie's abscess or osteoid osteoma. An osteoblastoma would have to be greater than 2 cm in size. A chondroblastoma may also have significant edema around it, but it is an epiphyseal-based lesion, not cortically based. The well-circumscribed nature of the lesion is not consistent with osteosarcoma. The pathology shows a very cellular and vascular stroma with plump, but not atypical osteoblast cells making a matrix of immature woven bone. There are no abundant inflammatory cells or dead bone suggestive of osteomyelitis or a Brodie's abscess. Therefore, the clinical and histologic picture is most consistent with an osteoid osteoma. Percutaneous radiofrequency ablation, usually with CT guidance, has become the preferred method for treating most cases of osteoid osteoma. Rosenthal DI: Radiofrequency treatment. Orthop Clin North Am 2006;37:475-484.
Question 2055
Topic: 10. Pathology and Oncology
What is the 5-year overall survival rate for adults with high-grade soft-tissue sarcomas?
Correct Answer & Explanation
. 50%
Explanation
The 5-year overall survival rate for deep, high-grade soft-tissue sarcomas is around 50%. The overall survival and disease-free survival rates chiefly depend on the tumor stage, but for all stages combined, most cancer treatment centers report a 5-year overall survival rate of around 70% and a disease-free survival rate of 65%. Fleming ID, et al: Manual for Staging of Cancer/American Joint Committee on Cancer, ed 5. Philadelphia, PA, Lippincott Raven, 1997, pp 149-156.
Question 2056
Topic: 10. Pathology and Oncology
A 14-year-old boy has had knee pain for the past 2 months. He 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?
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. McCarthy JJ, Dormans JP, Kozin SH, et al: Musculoskeletal infections in children: Basic treatment principles and recent advancements. Instr Course Lect 2005;54:515-528.
Question 2057
Topic: 10. Pathology and Oncology
A 43-year-old woman is referred after excisional biopsy of a cutaneous soft-tissue mass from her left shoulder. Based on the biopsy specimens shown in Figures 44a and 44b, what is the best course of action?
Correct Answer & Explanation
. Wide tumor bed resection
Explanation
Dermatofibrosarcoma protuberans (DFSP) is a rare superficial sarcoma that is frequently misdiagnosed at presentation. It is frequently excised prior to suspecting that the lesion is a sarcoma and if not appropriately treated with tumor bed resection to obtain wide margins, these lesions have a high incidence of local recurrence. It is recommended that the wide excision include the deep fascia and a 2.5- to 3-cm cuff of normal-appearing skin. Distant disease spread is rare and usually occurs in the face of a multiply recurrent lesion. Despite the apparent gross circumscription of these lesions, the tumor diffusely infiltrates the dermis and subcutaneous tissues. A characteristic histologic finding can be seen in the deep margins of the tumor where it intricately interdigitates with normal fat. Lindner NJ, Scarborough MT, Powell GJ, et al: Revision surgery in dermatofibrosarcoma protuberans of the trunk and extremities. Eur J Surg Oncol 1999;25:392-397.
Question 2058
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?
Correct Answer & Explanation
. Anterior decompression and stabilization
Explanation
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. Harrington KD: Metastatic tumors of the spine: Diagnosis and treatment. J Am Acad Orthop Surg 1993;1:76-86.
Question 2059
Topic: 10. Pathology and Oncology
A 47-year-old woman has had left medial clavicle pain for the past 6 months. History is remarkable for mediastinal non-Hodgkin's lymphoma, treated with mantel radiation 22 years ago. A radiograph, CT scan, MRI scan, and a biopsy specimen are shown in Figures 68a through 68d. What is the most likely diagnosis?
Correct Answer & Explanation
. Radiation-associated sarcoma
Explanation
Radiation-associated sarcomas typically occur at least 5 years following radiation therapy, in the radiation therapy field, and with different histology than the original disease. The radiograph shows a lytic destructive lesion of the medial clavicle. The radiographic differential could include any of the above etiologies. The CT and MRI scans show this same reaction with extension into the adjacent soft tissue and periosteal reaction. These findings eliminate a degenerative process or radiation-induced osteonecrosis but do not distinguish between a neoplastic and infectious process. A PET scan showed marked uptake in the distal clavicle, which is more consistent with a malignant neoplastic process than a reactive process, like that of an infection. These findings, combined with the cellular atypia and bone formation on the biopsy specimen, confirm the diagnosis of radiation-associated sarcoma. In this older patient, radiation-associated sarcoma appears in an unusual location secondary to her previous radiation treatment in that region, which can occur 3 to 50 years after previous radiation therapy. Shaheen M, Deheshi BM, Riad S, et al: Prognosis of radiation-induced bone sarcoma is similar to primary osteosarcoma. Clin Orthop Relat Res 2006;450:76-81.
Question 2060
Topic: 10. Pathology and Oncology
A 16-year-old girl has had painless swelling in her posterior left arm for the past 4 months. A radiograph, MRI scans, and an incisional biopsy specimen are shown in Figures 43a through 43d. What is the cytogenetic translocation most commonly associated with this tumor?
Correct Answer & Explanation
. (X; 18) (p11; q11)
Explanation
This is a case of synovial sarcoma. The radiograph shows some soft-tissue swelling in the upper arm. The MRI scans show a lesion that has increased signal on T2-weighted images and low signal on T1-weighted images. There is a suggestion of a large cystic component to this lesion. The pathology shows a biphasic population of cells, a spindle cell component, and an epithelioid component. Up to 20% of synovial cell sarcomas have areas of cyst formation. The most common cytogenetic translocation with synovial cell sarcoma is X; 18. The 11; 22 translocation is most commonly associated with Ewing's sarcomas; the 12; 22 translocation is most commonly associated with clear cell sarcomas; the 2; 13 translocation is most commonly associated with alveolar rhabdomyosarcomas, and the 12; 16 translocation is most commonly associated with myxoid liposarcomas. Kawai A, Woodruff J, Healey JH, et al: SYT-SSX gene fusion as a determinant of morphology and prognosis in synovial sarcoma. New Engl J Med 1998;338:153-160.
Test Yourself
Switch to an interactive, timed exam simulation to truly master this topic.
