10. Pathology and Oncology MCQs

DISCUSSION: 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. REFERENCES: 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. Wold LA, et al: Atlas of Orthopaedic Pathology. Philadelphia, PA, WB Saunders, 1990, p 232.

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.

The plain radiographs reveal a pedunculated osteochondroma with a fracture. There is a bony growth in the metaphysis of a long bone, on a stalk that is directed away from the nearby epiphysis. On the AP view, the host cortical and medullary bone are shown as “blending” with lesional bone. There is also a fracture through the lesion. Based on these radiographic findings, the diagnosis is an osteochondroma; therefore, initial management of an acute fracture of an osteochondroma is symptomatic treatment alone. Additional imaging studies are not indicated in this patient.

The history and laboratory studies indicate that this is not an infection. A lesion in this location and in this age group is likely a Ewing’s sarcoma. The presentation is usually a painful mass. About 20% of patients have a fever. The radiograph shows a typical mottled, permeative lesion with periosteal reaction. An MRI scan should be obtained to further evaluate the soft-tissue mass. Staging of the lesion should take place before biopsy, which should be done by the surgeon who would be performing the next stage of surgical treatment, ideally an orthopaedic oncologist.

Myeloma is a malignant bone tumor derived from plasma cells. It is associated with abnormalities of protein synthesis. It is the most common primary malignant tumor of bone. The disease is most common between the ages of 50 and 80. Patients most commonly present with bone pain, usually in the spine and ribs. Biopsy is necessary to establish the diagnosis in a solitary lesion and is still the gold standard for diagnosis of any lesion. Definitive diagnosis of multiple myeloma is established by bone marrow aspiration. However, multiple myeloma may also be diagnosed with considerable confidence based on radiographs and lab data. Bence Jones proteins may be found in the urine. Serum protein abnormalities may cause formation of a rouleaux in the peripheral blood smear. Serum and urine protein electrophoresis are usually abnormal. Answers #3, #4, and #5 may provide some information but the definitive diagnosis is based on bone marrow aspiration. Answer #1 provides little information.

The history of this pathologic fracture is unremarkable. What is notable, is the patient’s age, location, and x-ray appearance. Radiographically, there is an isolated, eccentric, intracortical osteolytic (bubble-like) tibia shown in figure.The differential diagnosis would include Adamantinoma (rarely seen under age 10, but commonly seen in the tibia), Fibrous dysplasia (usually older child and commonly seen in the tibia), Fibrous dysplasia (usually older child and commonly polyostotic), and Osteofibrous dysplasia (almost always prepubescent in age, isolated tibia/fibula, and eccentric osteolytic lesions).“The radiographic features are so characteristic that the diagnosis can often be made, with confidence, from the radiographs alone, before or without histological confirmation.”Therefore, any open biopsy or procedure answers would be wrong for test (OITE) purposes. However, it is not uncommon for thse to be biopsied and the pathology is also characteristic with two fundamental patterns: fibrous tissue surrounding bone trabeculae bordered by active osteoblasts and zonal architecture. Also, the absence of epithelia tissue would exclude adamantimona. Of note regarding Osteofibrous dysplasia, when biopsy/resection is performed, the benign tumor commonly locally returns if the patient is under age 10 to 15 years, but doesn’t if older.“Marginal subperiosteal excision should not be attempted in patients who are less than fifteen years old, because most likely the lesion will recur. In many cases a biopsy appears to be unnecessary, because clinically and radiographically the lesion is so typical that the physician can be reasonably confident about the diagnosis. The occasional pathological fracture can be treated by plaster-cast immobilization.”Question 197 -A 25-year-old woman who sustains a direct blow to the anteromedial aspect of her leg while playing basketball has immediate pain and cannot walk. Examination of the knee reveals an increase in posterior translation and external rotation at 90 degrees of flexion. At 30 degrees of flexion, posterior translation and external rotation decrease. Radiographs are normal. Which of the following structures has been injured?Posterolateral complexPosterior cruciate ligamentLateral collateral ligamentPosterior cruciate ligament and posterolateral complexPosterior cruciate ligament and medical collateral ligamentExternal rotation of the knee at 30 degrees of flexion averages 29 degrees with a range of 10-45. External rotation of the knee at 90 degrees of external rotation averages 37 degrees with a range of 15-

DISCUSSION: The patient has lung cancer metastatic to the right proximal femur. The lesion is large, has destroyed a portion of the cortex, and involves the peritrochanteric region. All of these findings put the patient at high risk for pathologic fracture. The lesion is amenable to intramedullary fixation in the form of some type of reconstruction nail. Chemotherapy alone will not restore the bone stock. Given the extent of the lesion, radiation therapy, chemotherapy, or embolization will not prevent fracture. A proximal femoral replacement would be indicated in patients with bone destruction extending into the femoral head and neck. Bisphosphonates may diminish the risk of subsequent lesions but are not sufficient to treat this high-risk lesion. Radiation therapy should be given postoperatively to prevent further bone destruction. REFERENCE: Mirels H: Metastatic disease in long bones: A proposed scoring system for diagnosing impending pathologic fractures. Clin Orthop 1989;249:256-264.

DISCUSSION: The radiographs show localized diffuse cortical thickening that is characteristic of melorheostosis. The condition may be monostotic or it may involve many bones in one extremity (monomelic) in the distribution of a sclerotome. Bone scans will show increased uptake at the site or sites of skeletal involvement. Long tubular bones are most commonly involved. Melorheostosis is usually asymptomatic and requires no treatment. On rare occasions, there may be associated soft-tissue contractures. REFERENCES: Dorfman H, Czerniak B: Bone Tumors. St Louis, MO, Mosby Inc, 1998, pp 1105-1107. Campbell CJ, Papademetriou T, Bonfiglio M: Melorheostosis: A report of the clinical, roentgenographic, and pathological findings in fourteen cases. J Bone Joint Surg Am 1968;50:1281-1304. Hove E, Sury B: Melorheostosis: Report on 5 cases with follow-up. Acta Orthop Scand 1971;42:315-319.

The radiograph shows enlargement of the bone, coarse trabeculation, a blastic appearance, and thickening of the cortex, revealing the classic appearance of Paget’s disease in the sclerotic phase, the most common presentation. While lymphoma may present as a blastic lesion, it will not have the same enlargement, coarse trabeculation of bone, and the significant sclerosis seen here.

The X-ray shows a mass in the leg with periosteal reaction in the fibula. The MRI shows a soft tissue mass arising from the fibula that looks aggressive. The pathology shows a bunch of small blue cells. The combination of small blue cells with a soft tissue mass and an onion skin appearance on X-ray in a patient in the 2nd decade of life is characteristic of Ewing sarcoma. 85% of Ewing sarcomas have the 11:22 translocation. None of the other answers are associated with Ewing sarcoma.

Prophylactic stabilization of impending fractures does not directly affect the overall survival rate, but it does improve factors related to intraoperative and postoperative complications and decreased recovery time.

Doxorubicin is a chemotherapeutic agent that is best known for dose-limiting cardiotoxicity. This is related not only to the cumulative dose, but also the rate of infusion.

DISCUSSION: The radiographic appearance of the lesion is lytic with calcifications in the supra-acetabular region. The CT scan shows bone destruction and periosteal reaction, which rules out an enchondroma. The histologic appearance is that of cellular cartilage, with a high cytoplasmic:nuclear ratio and basophilic appearance to the cytoplasm; these findings rule out chordoma and metastatic renal cell carcinoma. In addition, chordomas are most frequently found in the sacrum and base of the skull. Because there is no high-grade spindle cell component to suggest dedifferentiation, the most likely diagnosis is chondrosarcoma.

DISCUSSION: The history and physical examination are consistent with a monoarticular joint condition but not typical of joint sepsis. The arthroscopic appearance of brownish proliferative synovium is typical of PVNS. PVNS is a monoarticular synovial disease of unknown etiology and is treated with total synovectomy. The proliferative synovitis is not consistent with chondromalacia. Synovial cell sarcoma is an extracapsular disease. Rheumatoid arthritis typically is polyarticular, and the synovial appearance is not associated with hemosiderin deposition.

The patient has multiple hereditary exostoses and a secondary chondrosarcoma arising from a proximal femoral exostosis. The radiograph of the knee shows multiple osteochondromas typical in a patient with multiple hereditary exostoses. Patients with this diagnosis are at an increased risk for malignant degeneration of an osteochondroma. The lateral radiograph of the hip shows a bony lesion emanating from the anterior aspect of the femoral neck that is not well defined in the surrounding soft tissues. There are punctate calcifications and a large soft-tissue mass. The most likely diagnosis is a secondary chondrosarcoma developing from a benign osteochondroma. An enchondroma is an intramedullary benign cartilage lesion. Ollier’s disease and Maffucci’s syndrome involve multiple enchondromas. References: Scarborough M, Moreau G: Benign cartilage tumors. Orthop Clin North Am 1996;27:583-589. Garrison R, Unni K, McLeod RA, Pritchard DJ, Dahlin DC: Chondrosarcoma arising in osteochondroma. Cancer 1982;49:1890-1897.

This is an example of an unplanned excision. The patient has a history of trauma and a painless soft-tissue mass. The most common soft-tissue masses are benign; consequently, nononcologic surgeons may not expect a malignant sarcoma. The patient was taken to surgery with appropriate imaging and without a biopsy. If the imaging is conclusive, a biopsy is not always indicated, particularly for low-grade lipomatous tumors. The surgical resection was performed through a transverse incision. It is recommended that the incision be made longitudinally in the event a wider resection is needed. The grade of the tumor is the most important aspect. Benign and low-grade tumors may be observed, whereas intermediate and high-grade tumors require a wide resection and likely perioperative radiation. The appropriate work-up for a soft-tissue mass is a careful history and examination accompanied by radiographs and cross-sectional imaging. If a biopsy is needed, it should be performed or supervised by the surgeon who would do the final resection if it proves to be a sarcoma. The most common impact of an unplanned excision is wound complications. This is because of the need for a wider surgical resection and adjuvant radiation. Mortality and recurrence have not been shown to be increased with statistical significance. Functional outcome may be compromised; however, no studies confirm that functional outcome is poorer in patients who undergo unplanned excision.

The most likely diagnosis is osteosarcoma. The imaging studies show an aggressive primary tumor of bone, and the histology slide shows a typical chondroblastic osteosarcoma, with osteoid deposited along the surface of bone trabeculae. Ewing’s sarcoma histologically consists of small round blue cells. Osteochondroma and periosteal chondroma can occur near the knee but have different radiographic and histologic patterns. Chondrosarcoma rarely occurs in children. References: Simon M, Springfield D, et al: Osteogenic sarcoma: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 267. Wold LA, et al: Atlas of Orthopaedic Pathology. Philadelphia, PA, WB Saunders, 1990, pp 14-15.

DISCUSSION: MRI is the preferred imaging study to evaluate the local tumor extension for soft-tissue lesions, but CT can be used if MRI is contraindicated (e.g., patients with pacemakers). CT of the chest is always recommended in patients with high-grade sarcomas because 80% of metastases occur in the lungs. CT of the abdomen and pelvis is indicated in patients with lower extremity liposarcoma because some patients also have synchronous retroperitoneal liposarcoma. Lymph node metastasis occurs in up to 5% of patients with soft-tissue sarcoma. If the nodes are clinically enlarged, biopsy is indicated. Routine sentinel node biopsy currently is not recommended. Bone scan is not used in the staging of soft-tissue sarcoma as it has not been shown to be cost-effective.

DISCUSSION: The most common malignant disease to arise in conjunction with chronic osteomyelitis is squamous cell carcinoma particularly in patients with a long-standing draining sinus tract.