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10. Pathology and Oncology MCQs

Practice Set 107 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 2121

Topic: 10. Pathology and Oncology

Figures 21a and 21b show the radiographs of a 22-year-old man who has had progressive pain and swelling about the knee for the past 6 weeks. Examination reveals limited range of motion and fullness about the knee. What is the most likely diagnosis?

. Giant cell tumor
. Aneurysmal bone cyst
. Osteoblastoma
. Osteosarcoma
. Metastatic carcinoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

The radiographs reveal a destructive lesion in the metaphysis of the distal femur with periosteal changes and an associated soft-tissue mass with subtle mineralization. This suggests an aggressive malignant process. In this age group, the most likely diagnosis is osteosarcoma. Giant cell tumor, which usually is in a more subchondral location, is not typically so aggressive. Aneurysmal bone cyst is usually more geographic, with a well-marginated reactive rim. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 175-186.

Question 2122

Topic: Soft Tissue Tumors & Metastasis

Examination of the shoulder seen in Figure 52 shows atrophy and tenderness of the infraspinous fossa and profound weakness in external rotation. The supraspinous fossa shows normal muscle bulk. What is the most likely cause of this condition?

Shoulder Board Review 2002: High-Yield MCQs (Set 4) - Figure 18

. Neurofibroma of the suprascapular nerve
. Ganglion cyst of the suprascapular notch
. Ganglion cyst of the spinoglenoid notch
. Lipoma of the suprascapular notch
. Lipoma of the spinoglenoid notch

Correct Answer & Explanation

. Ganglion cyst of the spinoglenoid notch

Explanation

Compression of the suprascapular nerve by a ganglion cyst is a well-documented cause of pain and weakness in the shoulder. Isolated involvement of the infraspinatus indicates that the area of entrapment is at the spinoglenoid notch and not the suprascapular notch. The majority of ganglion cysts found in the shoulder are related to tears of the labrum. When such a compressive lesion is found, decompression can be accomplished through either an open or arthroscopic approach. Several authors have shown the value of arthroscopy in the treatment of this condition. It has been shown that it is technically possible to decompress a paralabral ganglion cyst using arthroscopy; this method is usually followed by repair of the torn labrum. Alternatively, arthroscopic repair of the labrum can be performed and the cyst may be aspirated at the time of surgery. Open cyst excision through a posterior approach is also an acceptable method of treatment. Schickendantz MS, Ho CP: Suprascapular nerve compression by a ganglion cyst: Diagnosis by magnetic resonance imaging. J Shoulder Elbow Surg 1993;2:110-114. Thompson RC, Schneider W, Kennedy T: Entrapment neuropathy of the inferior branch of the suprascapular nerve by ganglia. Clin Orthop 1982;166:185-187.

Question 2123

Topic: 10. Pathology and Oncology

A 29-year-old woman reports shoulder pain after sustaining a minor fall 6 weeks ago. She has a history of celiac sprue. Radiographs of the forearm and shoulder are shown in Figures 53a and 53b. Which of the following serum abnormalities would be expected?

. Elevated calcium level
. Elevated PTH level
. Elevated 1,25(OH)2D
. Elevated phosphate level
. Low alkaline phosphatase level

Correct Answer & Explanation

. Elevated PTH level

Explanation

Celiac sprue results in rapid gastrointestinal transit and fatty stools that impair the absorption of calcium and vitamin D and result in nutritional-deficiency osteomalacia with secondary hyperparathyroidism. The radiographs show marked osteopenia with brown tumors. A pathologic fracture is seen in the proximal humerus through a large brown tumor. Serum findings include low or normal calcium, low phosphate, elevated alkaline phosphatase, low 1,25(OH)2D, and increased PTH levels. Secondary hyperparathyroidism is associated with a variety of conditions including malabsorption syndromes. Potts JT: Parathyroid hormone: Past and present. J Endocrinol 2005;187:311-325. Corazza GR, Di Stefano M, Maurino E, et al: Bones in coeliac disease: Diagnosis and treatment. Best Pract Res Clin Gastroenterol 2005;19:453-465.

Question 2124

Topic: 10. Pathology and Oncology

Which of the following definitions best describes Batson's vertebral vein system?

Basic Science Board Review 2005: High-Yield MCQs (Set 2) - Figure 42

. A system of valves that allows retrograde embolism
. A vascular system that bypasses organs such as the breast, prostate, lung, kidney, and thyroid
. A system of veins within the thoracoabdominal cavity that are not subject to compression or collapse by increases in intra-abdominal pressure
. A series of valveless veins that allow tumor cell extravasation
. A longitudinal vein system with a segmental distribution to the vertebra that extends from the dural venous sinuses of the skull to the sacrum

Correct Answer & Explanation

. A longitudinal vein system with a segmental distribution to the vertebra that extends from the dural venous sinuses of the skull to the sacrum

Explanation

The venous plexus was described by Batson and helps to explain the common distribution of metastatic cells to the vertebrae, skull, ribs, and proximal long bones. Batson studied the vertebral vein system extensively by using contrast agents in human cadavers and live monkeys. Batson's plexus is a valveless system that allows retrograde embolism from the major organs such as the breast, prostate, lung, kidney, and thyroid. It is located within the thoracoabdominal cavity and has connections to the proximal long bones and an intercommunicating network of thin-walled veins with a low intraluminal pressure. Batson OV: Function of vertebral veins and their role in spread of metastases. Ann Surg 1940;112:138-149.

Question 2125

Topic: 10. Pathology and Oncology

A 21-year-old man has had right groin pain for the past year. A radiograph, CT scan, MRI scans, and a biopsy specimen are shown in Figures 50a through 50e. What is the most likely diagnosis?

. Chondrosarcoma
. Osteoblastoma
. Chondroblastoma
. Giant cell tumor of bone
. Subchondral cyst

Correct Answer & Explanation

. Chondrosarcoma

Explanation

The pathology demonstrates a very cellular chondroid matrix with multinucleated forms, atypia, and myxomatous regions. This is most consistent with a myxoid chondrosarcoma. The radiograph shows a well-circumscribed lesion in the superior and medial aspect of the right acetabulum. The CT and MRI scans confirm these same findings with no evidence of matrix mineralization or significant surrounding edema. Unfortunately, in this location with this appearance, the radiographic differential diagnosis includes all the diagnoses listed. Terek RM: Recent advances in the basic science of chondrosarcoma. Orthop Clin North Am 2006;37:9-14. Donati D, El Ghoneimy A, Bertoni F, et al: Surgical treatment and outcome of conventional pelvic chondrosarcoma. J Bone Joint Surg Br 2005;87:1527-1530.

Question 2126

Topic: 10. Pathology and Oncology

Eosinophilic granuloma frequently occurs as a solitary lesion in the tubular long bones. After biopsy, what is the best course of action?

Basic Science Board Review 2005: High-Yield MCQs (Set 2) - Figure 29

. Neoadjuvant chemotherapy
. En bloc resection
. Observation
. Amputation
. Chemotherapy followed by radiation therapy

Correct Answer & Explanation

. Observation

Explanation

Most lesions of eosinophilic granuloma are simply observed, but larger aggressive lesions may require curettage and bone grafting. Frequently, biopsy is required to rule out a malignant diagnosis. The differential diagnosis of eosinophilic granuloma is osteomyelitis, Ewing's sarcoma of bone, or osteogenic sarcoma. The biopsy alone can be followed by spontaneous resolution. In some patients, low-dose radiation therapy is used. Chemotherapy or amputation is not indicated for these benign lesions.

Question 2127

Topic: 10. Pathology and Oncology

A 14-year-old boy reports progressive right wrist pain. Radiographs are shown in Figure 3a, and a photomicrograph is shown in Figure 3b. What is the most likely diagnosis?

. Enchondroma
. Nonossifying fibroma
. Chondromyxoid fibroma
. Osteosarcoma
. Chondrosarcoma

Correct Answer & Explanation

. Chondromyxoid fibroma

Explanation

The radiographs show a benign-appearing, well-defined lytic lesion with a thin rim of surrounding reactive bone. The photomicrograph shows spindle cells with a myxoid cartilaginous matrix. These findings are diagnostic of chondromyxoid fibroma. This is a rare, benign tumor that usually causes pain and can be locally aggressive. Lersundi A, Mankin HJ, Mourikis A, et al: Chondromyxoid fibroma: A rarely encountered and puzzling tumor. Clin Orthop Relat Res 2005;439:171-175.

Question 2128

Topic: 10. Pathology and Oncology

Figure 16 shows the radiograph of a 7-year-old boy who sustained a pathologic fracture of the left humerus 1 day ago. Initial management should consist of

Pediatrics Board Review 2007: High-Yield MCQs (Set 2) - Figure 15

. a sling and swathe.
. needle biopsy of the lesion.
. a corticosteroid injection of the lesion.
. curettage and bone packing of the lesion.
. insertion of an intramedullary rod.

Correct Answer & Explanation

. a sling and swathe.

Explanation

The radiograph shows a pathologic fracture through a unicameral (simple) bone cyst (UBC). This is the most common location and presentation of a UBC. Less than 10% of UBCs heal spontaneously following a fracture. Urgent biopsy is not indicated because the lesion appears benign and the histology of fracture callus may be misinterpreted as osteosarcoma. After the fracture heals with the use of a sling and swathe, the UBC may be treated with a minimally invasive procedure such as injection of bone marrow and/or demineralized bone matrix. The chance for success is relatively low in an active cyst located adjacent to the physis. More invasive procedures, such as curettage, Rush rod fixation, or cannulated screw decompression, have been described but are rarely necessary for treatment of upper extremity cysts. Rougraff BT, Kling TJ: Treatment of active unicameral bone cysts with percutaneous injection of demineralized bone matrix and autogenous bone marrow. J Bone Joint Surg Am 2002;84:921-929. Robosch A, Saraph V, Linhart WE: Flexible intramedullary nailing for the treatment of unicameral bone cysts in long bones. J Bone Joint Surg Am 2000;82:1447-1453.

Question 2129

Topic: 10. Pathology and Oncology

A 70-year-old woman had poliomyelitis as a young child, and the residual weakness she has as an adult principally involves the lower extremities. She now notes progressive weakness in both legs and she tires easily. What is the best course of action?

Foot & Ankle 2000 Practice Questions: Set 1 (Solved) - Figure 17

. Gentle physical therapy and lifestyle modification to reduce demands on the symptomatic muscles
. Vigorous physical therapy to rehabilitate the weak muscle groups
. Muscle biopsy
. MRI of the lumbosacral spine
. Electromyography and nerve conduction velocity studies

Correct Answer & Explanation

. Gentle physical therapy and lifestyle modification to reduce demands on the symptomatic muscles

Explanation

The most likely diagnosis is postpolio syndrome, which is characterized by increasing weakness in both the paretic and previously normal muscles. Fatigability, joint pain, muscle atrophy, respiratory insufficiency, dysphagia, and sleep apnea are also seen. Gentle exercise and modification in lifestyle demands are generally recommended. Vigorous rehabilitation is likely to be detrimental in this condition. Further diagnostic work-up is not indicated at this time. Dalakas MC, Elder G, Hallett M, et al: A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms. N Eng J Med 1986;314:959-963.

Question 2130

Topic: 10. Pathology and Oncology

A previously healthy 14-year-old boy now reports fatigue, and has a bilateral Trendelenburg gait, right hip pain, and bilateral knee and foot pain. Biopsy of a right sacral mass reveals intermediate grade osteosarcoma. There are no metastases. Laboratory studies reveal a serum calcium level of 7.7 mg/dL (normal 8.5 to 10.5), a phosphate level of 2.0 mg/dL (normal 2.7 to 4.5), a 1,25-dihydroxyvitamin D level of less than 10 pg/mL (normal 18 to 62), a parathyroid hormone level of 19 pg/mL (normal 10 to 60), and an alkaline phosphatase level of 428 U/L (normal 15 to 351). What is the most likely cause of the patient's symptoms?

. Oncogenic rickets
. Calcium sequestration by the tumor
. Elevated alkaline phosphatase level
. Tumor cachexia
. L5 neuropathy

Correct Answer & Explanation

. Oncogenic rickets

Explanation

The laboratory findings are typical for rickets. Oncogenic rickets is a paraneoplastic syndrome that results from a substance secreted by the tumor that interferes with renal tubule reabsorption of phosphate. This substance previously had been called phosphatonin but recently has been identified as fibroblast growth factor 23. Nutritional rickets is rare in developed countries. Delayed onset familial hypophosphatemic rickets is possible, but the likelihood of having two rare diseases is unlikely. Osteosarcoma does not sequester calcium. Alkaline phosphatase levels can be elevated in osteosarcoma but does not cause muscle weakness. Tumor cachexia would occur only with advanced metastatic disease. A unilateral sacral mass would not cause a bilateral L5 neuropathy or the abnormal laboratory findings. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 29-2001. A 14-year-old with abnormal bones and a sacral mass. N Engl J Med 2001;345:903-908.

Question 2131

Topic: Bone Tumors

A 40-year-old man with an acetabular chondrosarcoma has a small soft-tissue mass. Treatment should consist of

Basic Science 2005 Practice Questions: Set 3 (Solved) - Figure 2

. chemotherapy with ifosfamide and doxorubicin hydrochloride.
. external beam radiation.
. wide resection.
. curettage and cementation of the pelvic lesion.
. cemented total hip arthroplasty with acetabular reconstruction.

Correct Answer & Explanation

. wide resection.

Explanation

The treatment of choice for pelvic chondrosarcoma is wide resection via an internal hemipelvectomy. Chondrosarcoma requires surgical resection for control and does not respond to traditional chemotherapy or external beam radiation. Hip arthroplasty with acetabular reconstruction and curettage and cementation of the lesion are intralesional procedures that result in a higher incidence of local recurrence of tumor. Pring M, Weber KL, Unni K, Sim FH: Chondrosarcoma of the pelvis: A review of sixty-four cases. J Bone Joint Surg Am 2001;83:1630-1642.

Question 2132

Topic: 10. Pathology and Oncology

A 65-year-old man has a painful mass of the middle finger. A clinical photograph, lateral radiograph, coronal MRI scan, and biopsy specimen are seen in Figures 20a through 20d. What is the most likely diagnosis?

. Giant cell tumor
. Chondrosarcoma
. Osteosarcoma
. Infection
. Paget's disease

Correct Answer & Explanation

. Chondrosarcoma

Explanation

Although the degeneration of an isolated benign cartilaginous lesion into a chondrosarcoma is rare, it occurs in roughly 10% of patients with Ollier's disease. Pain is the most common symptom of chondrosarcoma. The treatment of low-grade chondrosarcoma ranges from intralesional excision to wide amputation. The intent of the surgery is to remove all the disease to decrease the chance of local recurrence. Lee FY, Mankin HJ, Fondren G, et al: Chondrosarcoma of bone: An assessment of outcome. J Bone Joint Surg Am 1999;81:326-338.

Question 2133

Topic: 10. Pathology and Oncology

A 38-year-old woman with metastatic thyroid carcinoma has had increasing pain in the left hip for the past 3 months. An AP radiograph and coronal T1-weighted MRI scan are shown in Figures 28a and 28b. Management should consist of

. external beam radiation.
. curettage and cementation of the lesion with a compression hip screw and side plate fixation.
. curettage and cementation of the lesion with intramedullary fixation.
. cemented bipolar hemiarthroplasty.
. radioactive iodine infusion.

Correct Answer & Explanation

. cemented bipolar hemiarthroplasty.

Explanation

The radiograph and MRI scan reveal a lytic lesion in the left femoral neck region that extends to the lesser trochanter. Although external beam radiation and radioactive iodine infusion may be helpful in controlling the local disease, the patient is at high risk for femoral neck fracture given the location of the lesion. Prophylactic surgery is indicated; therefore, the treatment of choice is a cemented bipolar hemiarthroplasty. The use of a compression hip screw and side plate or an intramedullary nail has a high likelihood of failure with disease progression. Postoperative treatment with radiation therapy and bisphosphonates is also indicated. Mirels H: Metastatic disease in long bones: A proposed scoring system for diagnosing impending pathologic fractures. Clin Orthop 1989;249:256-264. Swanson KC, Pritchard DJ, Sim FH: Surgical treatment of metastatic disease of the femur. J Am Acad Orthop Surg 2000;8:56-65.

Question 2134

Topic: 10. Pathology and Oncology

An 11-year-old child has Ewing's sarcoma of the femoral diaphysis with a small soft-tissue mass. Staging studies show no evidence of metastases. Treatment should consist of

. chemotherapy and radiation therapy to the femur.
. chemotherapy and wide resection.
. chemotherapy and above-knee amputation.
. hip disarticulation.
. wide resection.

Correct Answer & Explanation

. chemotherapy and wide resection.

Explanation

The use of chemotherapy has dramatically improved survival rates of patients with Ewing's sarcoma. Local disease is best handled with wide resection to decrease local recurrence and to avoid the complications of radiation therapy (ie, secondary sarcomas). Radiation therapy alone is reserved for unresectable lesions or poor surgical margins. Amputation generally is not necessary. Toni A, Neff JR, Sudanese A, et al: The role of surgical therapy in patients with non-metastatic Ewing's sarcoma of the limbs. Clin Orthop 1991;286:225. Picci P, Rougraff BT, Bacci G, et al: Prognostic significance of histopathologic response to chemotherapy in non-metastatic Ewing's sarcoma of the extremities. J Clin Oncol 1993;11:1763.

Question 2135

Topic: 10. Pathology and Oncology

A 14-year-old boy reports pain in the distal thigh. He denies any history of trauma. Examination reveals tenderness and swelling of the distal thigh without effusion. A radiograph and CT scan are shown in Figures 10a and 10b. A biopsy specimen is shown in Figure 10c. Management should consist of

. wide excision with neoadjuvant chemotherapy.
. radiation therapy.
. curettage and bone grafting.
. observation.
. chemotherapy followed by radiation therapy.

Correct Answer & Explanation

. curettage and bone grafting.

Explanation

Based on these findings, the patient has an aneurysmal bone cyst. Frequently, fluid-fluid levels can be detected on MRI or CT images. The histologic results show a lesion that consists of cavernous spaces filled with blood. The lining of the cavity contains spindle cells, multinucleated giant cells, and reactive bone. Curettage and bone grafting is the preferred treatment method. Without treatment, these lesions can become quite large and destructive. Radiation therapy is not recommended for resectable lesions. Chemotherapy is not required for these benign lesions. Simon MA, Springfield DS, et al: Common Benign Bone Tumors: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, pp 194-200.

Question 2136

Topic: 10. Pathology and Oncology

Figure 9 shows the radiograph of a 75-year-old woman who reports the sudden onset of disabling medial knee pain. What is the most likely diagnosis?

Hip Board Review 2004: High-Yield MCQs (Set 2) - Figure 1

. Osteoarthritis
. Osteonecrosis
. Meniscal tear
. Metastatic lesion
. Synovial osteochondromatosis

Correct Answer & Explanation

. Osteonecrosis

Explanation

Idiopathic osteonecrosis of the medial femoral condyle occurs predominantly in women older than age 60 years. It is characterized by pain centered in the medial anterior aspect of the knee, and onset is sudden. Flattening, sclerosis, and the radiolucent crescent sign are radiographic indicators of osteonecrosis. The radiographs show no narrowing of the joint space or osteophyte formation to indicate osteoarthritis, and there are no loose bodies to indicate synovial osteochondromatosis. A meniscal tear is not consistent with the radiographic findings shown here. Meniscal tears can coexist with osteonecrosis, but the pain is not eliminated merely by partial meniscectomy. Metastatic lesions to the distal femoral epiphysis are exceedingly rare. Urbaniak JR, Jones JP Jr (eds): Osteonecrosis: Etiology, Diagnosis, and Treatment. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 413-418.

Question 2137

Topic: 10. Pathology and Oncology

A 13-year-old girl is referred for a painful progressive valgus deformity of the right knee. Examination reveals an antalgic gait with an obvious valgus deformity. The right distal femur has a palpable, tender mass with erythema and warmth. Figures 4a and 4b show a clinical photograph and a radiograph. Management should consist of

. needle biopsy of the distal femur.
. open reduction and internal fixation with a locking plate.
. closed reduction and fixation with a reamed antegrade locking intramedullary nail.
. referral to an orthopaedic oncologist for staging studies, biopsy, and definitive management.
. IV antibiotics for 6 weeks.

Correct Answer & Explanation

. referral to an orthopaedic oncologist for staging studies, biopsy, and definitive management.

Explanation

The radiograph shows a pathologic fracture through a destructive lesion of the distal femur metaphysis with osteolytic and osteoblastic features. The lateral cortex is destroyed, and there is periosteal new bone formation. These findings are consistent with malignancy, most likely an osteogenic sarcoma. Patients with suspected malignant tumors are best managed by surgeons with specific expertise in orthopaedic oncology. The biopsy of a malignant lesion should be deferred to the surgeon who is capable of definitive management of the patient. Enneking W: Principles of musculoskeletal oncologic surgery, in Evarts C (ed): Surgery of the Musculoskeletal System. New York, NY, Churchill Livingston, 1990.

Question 2138

Topic: 10. Pathology and Oncology

A 54-year-old woman reports worsening pain in her buttock, especially when sitting for long periods of time. She has occasional pain and paresthesias radiating down her posterior leg. She has no significant medical history. MRI scans are shown in Figures 15a and 15b and a biopsy specimen is shown in Figure 15c. What is the most likely diagnosis?

. Myxoid liposarcoma
. Myxoma
. Malignant fibrous histiocytoma
. Fibromatosis
. Neurofibroma

Correct Answer & Explanation

. Neurofibroma

Explanation

The biopsy specimen shows a wavy collagenous matrix with elongated cells; this is most consistent with neurofibroma. The patient has a mass in the region of the sciatic nerve. Imaging characteristics, homogeneous and very low signal on T1-weighted and very high signal on the T2-weighted sequences, are consistent with a myxoid-type lesion. These include myxoma, myxoid sarcomas, and nerve sheath tumors. Campanacci M: Bone and Soft Tissue Tumors, ed 2. New York, NY, Springer-Verlag, 1999, pp 1135-1136

Question 2139

Topic: 10. Pathology and Oncology

A 38-year-old man has an enlarging left paraspinal soft-tissue mass. Based on the MRI scans and biopsy specimens shown in Figures 32a through 32e, what is the most likely diagnosis?

. Fibromatosis
. Well-differentiated liposarcoma
. Synovial sarcoma
. Schwannoma
. Malignant fibrous histiocytoma

Correct Answer & Explanation

. Fibromatosis

Explanation

Fibromatosis is a benign but aggressive fibrous lesion that principally arises from the connective tissue of muscle and the overlying fascia. The peak incidence is between the ages of 25 and 35 years. Most patients have a deep-seated, firm, poorly circumscribed mass that has grown insidiously and causes little or no pain. MRI is helpful in diagnosing the lesion and in assessing the extent of disease prior to surgical intervention. Histologically, the lesion is poorly circumscribed and infiltrates the surrounding tissue. The lesion appears bland with uniform spindle cells separated by abundant collagen, with little or no cell-to-cell contact. Despite its bland microscopic appearance, the tumor frequently behaves in an aggressive manner. These lesions do not metastasize but have a high incidence of recurrence. Treatment options consist of surgical resection, radiation therapy, chemotherapeutic protocols, hormone modulation, and/or anti-inflammatory medications. Weiss SW, Goldblum JR, Enzinger FM: Enzinger and Weiss's Soft Tissue Tumors, ed 4. Philadelphia, PA, Elsevier, 2001, pp 309-337.

Question 2140

Topic: 10. Pathology and Oncology

A 34-year-old woman reports constant midlateral arm pain after sustaining minimal trauma to the shoulder. Radiographs and a biopsy specimen are shown in Figures 29a and 29b. What is the most likely diagnosis?

. Chondroblastoma
. Lymphoma
. Giant cell tumor
. Chondromyxoid fibroma
. Desmoplastic fibroma

Correct Answer & Explanation

. Giant cell tumor

Explanation

Eighty percent of giant cell tumors occur in patients older than age 20 years, with the peak incidence in the third decade of life. Most of these tumors are eccentrically located and epiphyseal in location. They are lytic in nature as in this patient. Although named for the hallmarked multinucleated giant cells seen in the lesion, the basic cell type is the spindle-shaped stromal cell. Chondroblastoma is highly cellular and contains large multinucleated giant cells with intercellular chondroid material, some of which is calcified. Chondromyxoid fibroma has chondroid tissue separated by strands of more cellular tissue with occasional multinucleated giant cells. Desmoplastic fibroma is characterized by poorly cellular fibrous tissue, and lymphoma is highly cellular with characteristic round cells. Campanacci M, Baldini N, Boriani S, et al: Giant cell tumor of bone. J Bone Joint Surg Am 1987;69:106-114.

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