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Question 2081

Topic: 10. Pathology and Oncology

A 17-year-old boy has had elbow pain for the past 6 weeks. A radiograph, MRI scans, and biopsy specimens are shown in Figures 65a through 65e. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Osteosarcoma
. Chondroblastoma
. Giant cell tumor

Correct Answer & Explanation

. Osteoblastoma


Explanation

The findings are consistent with an osteoblastoma. The radiographs show a bone-forming lesion of the distal humerus. The lesion has an osseous component extending out of the native cortex with a thin sclerotic border. The T2-weighted MRI scan shows the lesion extending anteriorly beyond the native cortex. No fluid-fluid levels are seen. Histology shows large osteoblasts producing osteoid and woven bone. The tissue between the spicules of bone and osteoid contains thin fibrous tissue and capillaries. Osteoid osteoma is a smaller lesion usually with sclerotic reactive bone around a small nidus. The histology differentiates osteoblastoma from osteosarcoma because no malignant cells are seen. There is no cartilage production or chondroblasts in the histologic specimen, eliminating chondroblastoma. Giant cell tumors of bone typically occur in a epiphyseal metaphyseal location, most commonly after skeletal maturity, and contain numerus giant cells. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 87-102.

Question 2082

Topic: 10. Pathology and Oncology

Figures 45a and 45b show the radiographs of a 46-year-old man who reports the acute onset of right knee pain and is unable to bear weight on the extremity. His medical history is unremarkable. The next most appropriate step in management should consist of

. intramedullary rod fixation.
. arterial embolization.
. skeletal traction and radiation therapy for 2 weeks.
. CT of the chest, abdomen, and pelvis, and serum protein electrophoresis.
. a skeletal survey and serum protein electrophoresis.

Correct Answer & Explanation

. CT of the chest, abdomen, and pelvis, and serum protein electrophoresis.


Explanation

The patient has a pathologic fracture of the right distal femur; therefore, given the patient's age, the most likely diagnosis is metastatic carcinoma. Staging studies should be obtained prior to surgical treatment. Immediate intramedullary fixation is contraindicated before a diagnosis is made by biopsy. Surgical stabilization should be performed prior to radiation therapy.

Question 2083

Topic: 10. Pathology and Oncology

A 21-year-old man has mild but persistent aching pain in his left proximal thigh during impact loading activities. He denies pain at rest and has no other symptoms. Figures 34a through 34e show the radiographs and T1-weighted, T2-weighted, and gadolinium MRI scans of the left hip. What is the most likely diagnosis?

. Enchondroma
. Giant cell tumor
. Osteosarcoma
. Simple bone cyst
. Histiocytosis

Correct Answer & Explanation

. Simple bone cyst


Explanation

The radiographs show a centrally located radiolucent lesion with cortical thinning and mild osseous expansion; these findings are the hallmarks of a simple bone cyst. Whereas this particular lesion does not demonstrate sclerosis, the distinct margin of this lesion with sharp transition to normal bone is common. The MRI scans reveal a purely cystic lesion with bright T2 signal, and the gadolinium image shows the classic rim enhancement of cystic lesions. Fibrous dysplasia with cystic degeneration might have a very similar appearance and should be considered in the differential diagnosis. Parsons TW: Benign bone tumors, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1027-1035. May DA, Good RB, Smith DK, et al: MR imaging of musculoskeletal tumors and tumor mimickers with intravenous gadolinium: Experience with 242 patients. Skeletal Radiol 1997;26:2-15.

Question 2084

Topic: 10. Pathology and Oncology

Figure 26a shows the radiograph of a 55-year-old woman who has pain in her right leg after falling. Laboratory studies reveal an elevated alkaline phosphatase level. A biopsy specimen from the proximal tibia is shown in Figure 26b. What is the most likely diagnosis?

. Metastatic breast cancer
. Fibrous dysplasia
. Paget's disease
. Hyperparathyroidism
. Rheumatoid arthritis

Correct Answer & Explanation

. Paget's disease


Explanation

Paget's disease of bone is a metabolic disorder of bone remodeling. The normally coupled process of bone resorption and deposition is lost, resulting in excessive localized bone resorption and compensatory increased bone formation. Pagetic bone tends to be more brittle; therefore, it is susceptible to pathologic fractures and subsequent deformities. Lander PH, Hadjipavlou AG: A dynamic classification of Paget's disease. J Bone Joint Surg Br 1986;68:431-438.

Question 2085

Topic: 10. Pathology and Oncology

Figures 29a and 29b show the AP radiograph and CT scan of a 70-year-old man who has left thigh pain. Serum protein electrophoresis shows a monoclonal gammopathy. Additional radiographs of the femur show other lesions. Management should consist of

. chemotherapy, wide resection, and endoprosthetic reconstruction.
. radiation therapy only.
. chemotherapy only.
. prophylactic internal fixation with a locked intramedullary rod.
. open curettage, bone grafting, dynamic hip screw fixation, and radiation therapy.

Correct Answer & Explanation

. prophylactic internal fixation with a locked intramedullary rod.


Explanation

The underlying diagnosis is multiple myeloma. Because the patient has a large lucent lesion in the peritrochanteric region of the left proximal femur, the risk of pathologic fracture is high. Consideration should be given to prophylactic internal fixation with a locked intramedullary rod. The lesion does not appear to be a sarcoma requiring wide resection and endoprosthetic reconstruction. Neither chemotherapy nor radiation therapy alone is likely to result in long-term stabilization of the proximal femur. Postoperative treatment with bisphosphonates and radiation therapy is indicated to decrease the risk of future pathologic fractures. The patient should also be referred to a medical oncologist for medical management. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 364.

Question 2086

Topic: 10. Pathology and Oncology

A 16-year-old girl has had pain in the left groin for the past 4 months. She notes that the pain is worse at night; however, she denies any history of trauma and has no constitutional symptoms. There is no history of steroid or alcohol use. Examination reveals pain in the left groin with rotation of the hip. There is no associated soft-tissue mass. A radiograph and MRI scan are shown in Figures 32a and 32b, and biopsy specimens are shown in Figures 32c and 32d. What is the most likely diagnosis?

. Clear cell chondrosarcoma
. Chondroblastoma
. Giant cell tumor
. Aneurysmal bone cyst
. Osteonecrosis of the femoral head

Correct Answer & Explanation

. Chondroblastoma


Explanation

Based on the epiphyseal location and sharp, well-defined borders, the radiograph suggests chondroblastoma. Histologically, multinucleated giant cells are scattered among mononuclear cells. The nuclei are homogenous and contain a characteristic longitudinal groove. Although not seen here, "chicken-wire calcification" with a bland giant cell-rich matrix is also typical for chondroblastoma. Clear cell chondrosarcoma occurs in epiphyseal locations but has a more aggressive histologic pattern and occurs in an older age group. Giant cell tumors occur in the epiphysis but have a more uniform giant cell population histologically. Aneurysmal bone cyst often results in bone remodeling and has a different pathologic appearance. Osteonecrosis has a typical histologic pattern of empty lacunae and necrotic bone. Springfield DS, Capanna R, Gherlinzoni F, et al: Chondroblastoma: A review of seventy cases. J Bone Joint Surg Am 1985;67:748-755. Simon M, Springfield D, et al: Chrondroblastoma: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 190.

Question 2087

Topic: 10. Pathology and Oncology

A 53-year-old man has a 4- x 5-cm high-grade soft-tissue sarcoma in the midthigh. As part of the staging evaluation, regional nodes should be assessed by

Basic Science 2002 Practice Questions: Set 1 (Solved) - Figure 42

. CT of the pelvis and groin.
. sentinal node biopsy.
. clinical examination.
. fine needle aspiration.
. prophylactic inguinal node dissection.

Correct Answer & Explanation

. clinical examination.


Explanation

In general, soft-tissue metastases to regional nodes are a relatively rare occurrence (less than 5% overall). The incidence of lymphatic metastasis is highest for synovial sarcoma, rhabdomyosarcoma, clear cell sarcoma, and epithelioid sarcoma. Regional nodes should be assessed clinically. CT is not used to routinely assess regional nodes. Evaluation of a sentinal node is not indicated because of the low incidence of regional nodal involvement. Fine needle aspiration may be indicated to assess clinically suspicious nodes. Prophylactic inguinal node dissection is contraindicated because it may lead to unnecessary complications such as lymphedema.

Question 2088

Topic: 10. Pathology and Oncology

An 83-year-old woman reports pain in her left middle finger after a minor injury. Laboratory studies show a WBC count of 7,000/mm3, an erythrocyte sedimentation rate of 3 mm/h, a uric acid of 10.4 mg/dL, and a normal serum protein electrophoresis. Radiographs are shown in Figures 49a and 49b. A core biopsy specimen is shown is Figure 49c. In addition to treatment of the finger fracture, treatment should include

. colchicine and indomethacin
. radiation therapy to the left hand.
. systemic chemotherapy.
. IV antibiotics.
. through the wrist amputation.

Correct Answer & Explanation

. colchicine and indomethacin


Explanation

This clinical picture is most consistent with periarticular erosions from gout. The patient has multiple periarticular lytic lesions in the hand. The laboratory studies show an elevated serum uric acid level, and the biopsy specimen demonstrates acute and chronic inflammation with prominent clefts. Therefore, the preferred treatment is systemic control of her gout. Radiation therapy, chemotherapy, and/or amputation should be considered for a malignancy; however, the pathology does not demonstrate any evidence of pleomorphism, high nuclear-to-cytoplasmic ratio, nuclear atypia, or mitotic activity. Antibiotics for an infectious process is a consideration, but the minimal elevation in the WBC count and erythrocyte sedimentation rate does not support an infectious process. Wise CM: Crystal-associated arthritis in the elderly. Clin Geriatr Med 2005;21:491-511.

Question 2089

Topic: 10. Pathology and Oncology

An infant is born with a mass that involves both the volar and dorsal compartments of the left arm. A clinical photograph and biopsy specimen are shown in Figures 41a and 41b. What is the best initial course of action?

. Debulking
. Wide resection with vascular and nerve grafting
. Above-elbow amputation
. Chemotherapy
. Radiation therapy

Correct Answer & Explanation

. Chemotherapy


Explanation

The patient has infantile fibrosarcoma. For unresectable lesions, the treatment of choice is chemotherapy with vincristine, actinomycin-D, and cyclophosphamide, followed by excision if there is an adequate decrease in the size of the lesion.

Question 2090

Topic: 10. Pathology and Oncology

A 52-year-old woman reports nagging shoulder pain that has been present for months and is slowly progressive in nature. The patient also reports nocturnal pain and notes that the pain is not activity related. Figures 27a and 27b show the radiograph and bone scan, and Figures 27c through 27e show T1-weighted, T2-weighted, and gadolinium MRI scans, respectively. Based on these findings, what is the most likely diagnosis?

. Aneurysmal bone cyst
. Enchondroma
. Plasmacytoma
. Giant cell tumor
. Chondrosarcoma

Correct Answer & Explanation

. Chondrosarcoma


Explanation

The radiograph reveals a metaphyseal lesion with some stippled mineralization suggesting a chondroid tumor. The bone scan shows increased uptake, beyond what is expected for a simple enchondroma, and beyond the limits of the lesion. The MRI sequences shows a lobular lesion on the T1- and T2-weighted (bright on the T2 sequence) images with inhomogeneous uptake of gadolinium; both findings are typical for a chondroid lesion. The history of pain, the positive bone scan, the age of the patient, the size of the lesion, and the central location (enostotic) of the lesion all suggest a malignant cartilage tumor. The images are not consistent with the other diagnoses. In particular, plasmacytoma is more uniformly bright on T2-weighted images and often has a negative bone scan. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 187-194.

Question 2091

Topic: 10. Pathology and Oncology

A 65-year-old woman has had chronic aching discomfort involving her elbow for the past 6 months. Radiographs and a biopsy specimen are shown in Figures 38a through 38c. What is the most likely diagnosis?

. Metastatic carcinoma (thyroid)
. Multiple myeloma
. Lymphoma
. Synovial cell sarcoma
. Osteomyelitis

Correct Answer & Explanation

. Multiple myeloma


Explanation

The histologic features of multiple myeloma are distinctive for this lesion. The plasma cells are round or oval and have an eccentric nucleus and prominent nucleolus. These characteristics and a clear area next to the eccentric nucleus representing the prominent Golgi center are pathognomonic for plasma cells. Lymphoma is in the differential diagnosis; the most frequent types that occur in bone are large cell or mixed small and large cell types. The histologic appearance of the specimen is not consistent with the other choices.

Question 2092

Topic: Bone Tumors

Figures 4a through 4c show the radiographs, CT scans, and T1-weighted MRI scan of a 19-year old man who has had increasing right hip pain and decreasing range of motion for the past several years. He also reports intermittent "locking" of the hip. What is the most likely diagnosis?

. Chondrosarcoma
. Stress fracture
. Osteochondroma
. Osteosarcoma
. Synovial osteochondromatosis

Correct Answer & Explanation

. Synovial osteochondromatosis


Explanation

The radiographs reveal small ossified masses around the femoral neck. The CT scans also show these masses and suggest that they are separate from the underlying cortex of the femoral neck, although they abut it. The MRI scan does not reveal significant marrow changes in the proximal femur apart from some mild reactive changes immediately adjacent to the nodules. These findings suggest a synovial or joint-based disorder as opposed to a primary bone tumor. The most likely diagnosis is synovial osteochondromatosis, which is consistent with the patient's mechanical symptoms. Crotty JM, Monu JU, Pope TL Jr: Synovial osteochondromatosis. Radiol Clin North Am 1996;34:327-342.

Question 2093

Topic: 10. Pathology and Oncology

Figure 26 shows the radiograph of a 48-year-old woman who has right arm pain and hematuria. A bone scan reveals increased uptake in the left ribs and thoracic spine. A needle biopsy specimen shows that the lesion is highly keratin positive and composed primarily of clear cells. What is the best course of action?

Basic Science Board Review 2005: High-Yield MCQs (Set 2) - Figure 43

. Interleukin-2-based chemotherapy
. Embolization followed by curettage, intramedullary fixation, and cementation
. Embolization followed by curettage and cementation
. External beam radiation
. Total humeral resection and prosthetic reconstruction

Correct Answer & Explanation

. Embolization followed by curettage, intramedullary fixation, and cementation


Explanation

The lesion has the typical "blown out" lytic radiographic appearance that is most commonly found in thyroid or renal cell metastases. Given the history of hematuria and histology findings, the most likely diagnosis is metastatic renal cell carcinoma. This tumor is relatively resistant to chemotherapy. Radiation therapy is used as a postoperative adjuvant treatment with varying response rates. Surgery should be performed after preoperative embolization to decrease the risk of intraoperative bleeding, as no tourniquet can be used in this location. Patients with metastatic renal cell carcinomas may survive for years, resulting in a higher likelihood of local tumor progression with ineffective adjuvant therapy. Intramedullary fixation combined with curettage and cementation will provide the best chance of local control while maintaining the patient's native shoulder and elbow joints. A total humeral resection is an extensive surgery with considerable morbidity and is not indicated for this patient because less extensive surgery is likely to be effective. Harrington KD, Sim FH, Enis JE, Johnston JO, Diok HM, Gristina AG: Methylmethacrylate as an adjunct in internal fixation of pathological fractures: Experience with three hundred and seventy-five cases. J Bone Joint Surg Am 1976;58:1047-1054. Sun S, Lang EV: Bone metastases from renal cell carcinoma: Preoperative embolization. J Vasc Interv Radiol 1998;9:263-269.

Question 2094

Topic: 10. Pathology and Oncology

A 35-year-old man reports the development of a painful 2-cm nodule on his dorsal wrist over the past 3 years. A surgeon excised the lesion with a presumptive diagnosis of a ganglion cyst. Histology sections from the excision are shown in Figures 11a and 11b. What is the most likely diagnosis?

. Ganglion cyst
. Clear cell sarcoma
. Epithelioid sarcoma
. Epidermal inclusion cyst
. Synovial sarcoma

Correct Answer & Explanation

. Clear cell sarcoma


Explanation

The histologic appearance of the soft-tissue lesion reveals compact nests of cells with a clear cytoplasm surrounded by a delicate border of fibrocollagenous tissue. There can be scattered multinucleated giant cells. This is consistent with a clear cell sarcoma, also called malignant melanoma of soft parts. This tumor is usually positive for S-100 and HMB45 (a melanoma-associated antigen). These tumors are frequently found around the foot and ankle. Similar to epithelioid sarcoma, it is usually intimately bound to tendons or tendon sheaths. Often the tumors are present for many years. The classic histologic appearance of this lesion differentiates it from the other choices. Enzinger FM, Weiss SW: Soft Tissue Tumors, ed 3. St Louis, MO, Mosby, 1995, p 913.

Question 2095

Topic: 10. Pathology and Oncology

A 16-year-old girl has a painful foot mass. A radiograph, MRI scan, and biopsy specimens are shown in Figures 35a through 35d. What is the most likely diagnosis?

. Synovial sarcoma
. Pigmented villonodular synovitis (PVNS)
. Malignant fibrous histiocytoma
. Synovial chondromatosis
. Lyme disease

Correct Answer & Explanation

. Pigmented villonodular synovitis (PVNS)


Explanation

Synovial sarcoma should always be considered in the differential diagnosis of a foot mass; however, the histopathology shows a typical example of PVNS, with hemosiderin, giant cells, and synovium. Synovial chondromatosis would have metaplastic cartilage in the synovium. The radiograph shows subtle erosion of the lateral cortex of the cuboid, and the MRI scan shows a soft-tissue mass. Ghert MA, Scully SP, Harrelson JM: Pigmented villonodular synovitis of the foot and ankle: A review of six cases. Foot Ankle Int 1999;20:326-330. Jones BC, Sundaram M, Kransdorf MJ: Synovial sarcoma: MR imaging findings in 34 patients. Am J Roentgenol 1993;161:827-830. Sartoris DJ, Resnick D: Magnetic resonance imaging of pediatric foot and ankle disorders. J Foot Surg 1990;29:489-494.

Question 2096

Topic: 10. Pathology and Oncology

Figure 18a shows the clinical photograph of a 31-year-old man who has a slowly growing nodule on his right middle finger. It is minimally tender, and there is no erythema on examination. A biopsy specimen is shown in Figure 18b. What is the most likely diagnosis?

. Clear cell sarcoma
. Clear cell carcinoma
. Epidermal inclusion cyst
. Nora's tumor (BPOP)
. Epithelioid sarcoma

Correct Answer & Explanation

. Epithelioid sarcoma


Explanation

Epithelioid sarcoma is the most common soft-tissue sarcoma in the hand and most commonly occurs in young adults. The tumors can be superficial and may become ulcerated. Deeper lesions are often attached to tendons, tendon sheaths, or fascial structures. These are usually minimally symptomatic. The biopsy specimen reveals the typical appearance of a nodular pattern with central necrosis. They can mimic a necrotizing granulomatous process. Usually there are chronic inflammatory cells along the margin of the tumor nodules. This biopsy specimen does not have the clear cells necessary for a clear cell carcinoma or sarcoma. Nora's tumor is a bizarre parosteal osteochondromatous proliferation (BPOP) first described in 1983 by the pathologist, Nora. The lesion is defined as a reactive heterotopic ossification and is mostly found in the hands or feet of adults in the third decade of life. Enzinger FM, Weiss SW: Soft Tissue Tumors, ed 3. St Louis, MO, Mosby, 1995, p 1074.

Question 2097

Topic: Bone Tumors

A 9-year-old boy has a painless enlarged mass on the dorsum of his hand. Figures 14a through 14d show the clinical photograph, radiographs, and biopsy specimen. What is the most likely diagnosis?

. Fracture callus
. Enchondroma (Ollier's disease)
. Multiple hereditary exostosis
. Osteosarcoma
. Chondrosarcoma

Correct Answer & Explanation

. Multiple hereditary exostosis


Explanation

Multiple hereditary exostosis and enchondroma commonly present as multiple lesions in the hand. Multiple hereditary exostosis consists of cartilage capped bony exostoses arising from the metaphyseal end of rapidly growing bones. Osteosarcoma and chondrosarcoma rarely appear as multiple lesions. Fracture callus can exhibit enchondral ossification that is usually circumferential, but the radiographic findings are not consistent with fracture. Porter DE, Emerton ME, Villanueva-Lopez F, Simpson AH: Clinical and radiographic analysis of osteochondromas and growth disturbance in hereditary multiple exostoses. J Pediatr Orthop 2000;20:246-250.

Question 2098

Topic: 10. Pathology and Oncology

Which of the following lesions most closely resembles Ewing's sarcoma histologically?

. Metastatic neuroblastoma
. Osteosarcoma
. Osteomyelitis
. Fibrous dysplasia
. Fracture healing

Correct Answer & Explanation

. Metastatic neuroblastoma


Explanation

Ewing's sarcoma is characterized by small round blue cells. Lesions with a similar appearance include lymphoma, primitive neuroectodermal tumor, rhabdomyosarcoma, small cell lung tumor, and metastatic neuroblastoma. Karyotyping, immunohistochemistry, and electron microscopy can help differentiate these lesions.

Question 2099

Topic: Bone Tumors

An otherwise healthy 33-year-old man who works in construction reports a 3-month history of knee pain. Radiographs are shown in Figures 9a and 9b. An axial T1-weighted MRI scan with contrast, an angiogram, and histologies are shown in Figures 9c through 9f. What is the most likely diagnosis?

. Conventional osteosarcoma
. Myositis ossificans
. Osteochondroma
. Parosteal osteosarcoma
. Dedifferentiated parosteal osteosarcoma

Correct Answer & Explanation

. Dedifferentiated parosteal osteosarcoma


Explanation

Dedifferentiated parosteal osteosarcoma designates high-grade transformation of conventional low-grade parosteal osteosarcoma. Unlike conventional parosteal osteosarcoma, where wide surgical excision alone is considered adequate treatment, patients with dedifferentiated osteosarcoma are treated with neoadjuvant chemotherapy and wide local resection. Recognition of dedifferentiated areas with angiography can localize the area that should be biopsied and thus render an accurate diagnosis. Percutaneous biopsy of hypervascular areas should prompt the administration of chemotherapy and wide local excision to optimize patient outcome. Sheth DS, Yasko AW, Raymond AK, et al: Conventional and dedifferentiated parosteal osteosarcoma: Diagnosis, treatment, and outcome. Cancer 1996;78:2136-2145.

Question 2100

Topic: 10. Pathology and Oncology

An otherwise healthy 32-year-old man who underwent an uneventful L5-S1 lumbar microdiskectomy 6 weeks ago now reports increasing and severe back pain that awakens him from sleep. Examination reveals a benign-appearing wound, and the neurologic examination is normal. Laboratory studies show an erythrocyte sedimentation rate (ESR) of 90 mm/h and a WBC of 9,000/mm3. Plain radiographs are normal. What is the next most appropriate step in management?

. Oral antibiotics for staphylococcus
. Repeat laboratory studies in 1 week to recheck the ESR
. MRI with gadolinium
. Biopsy of the surgical disk space
. Irrigation and debridement of the surgical wound in the operating room

Correct Answer & Explanation

. MRI with gadolinium


Explanation

The patient's history and laboratory studies are very suspicious for a postoperative diskitis. The predominant symptom often is back pain. An ESR of 90 mm/h is considered significantly elevated and normally would be expected to return to near baseline by 2 weeks postoperatively. A normal WBC result is not unusual with postoperative diskitis. Management should consist of an MRI with gadolinium to confirm the diagnosis, followed by a biopsy percutaneously to obtain tissues for pathology and microbiology. Surgical debridement is reserved for patients whose percutaneous biopsy results are negative and a high index of suspicion for diskitis remains, or when management consisting of IV antibiotics, bed rest, and spinal immobilization fails to provide relief. Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 257-271.