10. Pathology and Oncology MCQs

DISCUSSIONFigures 14a through 14e show a 13-year-old boy with osteomyelitis of the distal tibia and a large subperiosteal abscess. The patient has failed treatment with IV ceftriaxone, and methicillin-resistant Staphylococcus aureus infection is likely. Aspiration, cultures, irrigation and debridement, IV vancomycin, an infectious disease consult, and an evaluation for possible deep vein thrombosis is prudent initial treatment. Figure 15a through 15c show a 7-year-old girl who sustained a deer tick bite while vacationing in Connecticut. She has Lyme arthritis and a Lyme “bulls-eye” rash on the same leg. Aspiration, cultures, Lyme serology, and oral amoxicillin for 30 days is prudent initial treatment. Figures 16a and 16b are the radiograph and MR image of a 15-year-old dance athlete with a probable minor fracture via a benign cyst of the distal femur. The geographic cyst may be a nonossifying fibroma, eosinophilic granuloma, Brodie abscess, or simple bone cyst. Biopsy, culture, curettage and bone graft, and possible internal fixation is reasonable initial treatment.

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.

DISCUSSION: 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. REFERENCES: Sailer SL: The role of radiation therapy in localized Ewing’ sarcoma. Semin Radiat Oncol 1997;7:225-235. Shankar AG, Pinkerton CR, Atra A, Ashley S, Lewis I, Spooner D, et al: Local therapy and other factors influencing site of relapse in patients with localised Ewing’s sarcoma. United Kingdom Children’s Cancer Study Group (UKCCSG). Eur J Cancer 1999;35:1698-1704. Carrie C, Mascard E, Gomez F, Habrand JL, Alapetite C, Oberlin O, et al: Nonmetastatic pelvic Ewing sarcoma: Report of the French society of pediatric oncology. Med Pediatr Oncol 1999;33:444-449. Terek RM, Brien EW, Marcove RC, Meyers PA, Lane JM, Healey JH: Treatment of femoral Ewing’s sarcoma. Cancer 1996;78:70-78.

DISCUSSION: 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. REFERENCES: Marks KE, Bauer TW: Fibrous tumors of bone. Orthop Clin North Am 1989;20:377. Ponseti IV, Friedman B: Evaluation of metaphyseal fibrous defects. J Bone Joint Surg Am 1949;31:582.

DISCUSSION: When a unicameral cyst is present in the setting of a pathological fracture, it is best to allow the fracture to heal before administering interventions for the cyst. In some cases, waiting may obviate the need for a procedure to manage the cyst. When indicated, the initial procedure of choice is aspiration and injection of the cyst. Although many variations of the procedure exist, current evidence continues to support the role of methylprednisolone in the injection portion of the procedure. Curettage and packing may sometimes be appropriate for recalcitrant cysts, but is not indicated for this patient. These cysts are typically solitary and are not considered at risk for malignant degeneration or systemic involvement; therefore, further distant imaging and biopsy is unnecessary.

DISCUSSION: The sagittal T2-weighted and axial T2-weighted images show a lesion within the T8 vertebral body that involves the posterior elements. There is an associated epidural component that results in compression of the spinal cord. The sagittal reconstructed CT image shows a lytic lesion within the T8 vertebral body. This pattern of vertebral body involvement with preservation of the adjacent disks and endplates in a 65-year-old patient is most compatible with a diagnosis of a tumor. The most likely tumor is a metastatic lesion. A CT-guided biopsy will confirm this diagnosis. Although thoracic tuberculosis does not typically cross the disk space, the lack of an anterior soft-tissue component decreases the likelihood of this diagnosis. RECOMMENDED READINGS: Khanna AJ, Shindle MK, Wasserman BA, Gokaslan ZL, Gonzales RA, Buchowski JM, Riley LH 3rd. Use of magnetic resonance imaging in differentiating compartmental location of spinal tumors. Am J Orthop (Belle Mead NJ). 2005 Oct;34(10):472-6. Review. PubMed PMID: 16304794. White AP, Kwon BK, Lindskog DM, Friedlaender GE, Grauer JN. Metastatic disease of the spine. J Am Acad Orthop Surg. 2006 Oct;14(11):587-98. Review. PubMed PMID: 17030592.

DISCUSSION: Neurilemoma is a benign tumor of nerve sheath origin, and peak incidence is in the third through sixth decades. The tumor is well encapsulated on the surface of a peripheral nerve. MRI findings may be significant for a “string sign.” A positive Tinel’s sign in the distribution of the nerve affected may be present. Grossly, the lesion is well encapsulated in a nerve sheath. Microscopically, there are structures referred to as Antoni A (a pattern of spindle cells arranged in intersecting bundles) and Antoni B (areas with less cellularity with loosely arranged cells). These lesions are benign, and treatment should consist of marginal excision. Nerve function may be preserved by careful dissection, excising the lesion parallel to the nerve fascicles so the lesion may be extruded. Recurrence is rare.

This patient has osteoid osteoma (OO). OO and osteoblastoma (OB) of the spine commonly present in the 2nd decade of life. CT shows a low attenuation nidus with central mineralization and varying degrees of perinidal sclerosis. NSAIDs are thought to inhibit PGE2 and PGI2 produced within the nidus, and suppress perinidal edema arising from high levels of COX2 expression in neoplastic nidal osteoblasts. OOs of the spine are the most common cause of painful scoliosis in children and young adults. Figures A and B are bone scan and SPECT scans respectively that demonstrate intense tracer uptake in the left transverse process of L3 characteristic of an osteoid osteoma. Figures C and D are axial and coronal reconstructed CT images showing a lesion of the left transverse process of L3 with a dense "nidus" with surrounding lucency characteristic of osteoid osteoma.

DISCUSSION: The radiograph reveals bilateral patchy sclerosis of the femoral heads without evidence of collapse. The MRI scan shows bilateral head involvement with a common serpentine-like low-intensity signal of the superior femoral head that is common to osteonecrosis. Changes confined to the femoral head effectively exclude rheumatoid arthritis and osteoarthritis. REFERENCES: Resnick D (ed): Diagnosis of Bone and Joint Disorders, ed 4. Philadelphia, PA, WB Saunders, 2002, vol 4, pp 3160-3162. Epstein RE, Dalinka MK: Ischemic necrosis, in Stark DD, Bradley WG (eds): Magnetic Resonance Imaging, ed 3. St Louis, MO, Mosby, 1999, vol 2, pp 1023-1027.

DISCUSSION: Casali and associates provided a recent review of the treatment options for chordomas. These tumors are not radiosensitive; however, modern intensity modulated radiosurgery techniques may be of value. The combination of surgery and radiotherapy compared to surgery alone results in the same disease-free survival time. Complete surgical resection of the chordoma with clean margins offers the best survival; however, its location may make total removal impossible. Thus subtotal resection followed by radiotherapy results in better survival despite the tumor’s lack of radiosensitivity. REFERENCE: Casali PG, Stacchiotti S, Sangalli C, et al: Chordoma. Curr Opin Oncol 2007;19:367-370.

Discussion: The imaging shows a soft-tissue mass with histology showing a synovial sarcoma. This histology is associated with t(X;18). Ewing sarcoma is associated with t(11;22); alveolar rhabdomyosarcoma with t(2;13); and myxoid liposarcoma with t(12;16). Although the presented monophasic histology could be consistent with other sarcomas, it does not have the characteristics of Ewing sarcoma (small round blue cells), alveolar rhabdomyosarcoma (alveolar pattern), or myxoid liposarcoma (myxoid stroma and signet ring lipoblasts with a plexiform capillary network).

DISCUSSION: Chondrosarcomas associated with diffuse bone lesions (enchondromas) are characteristic of Ollier’s disease. When accompanied by subcutaneous masses (hemangiomas), the condition is called Maffucci’s syndrome. Multiple hereditary exostosis is characterized by diffuse osteochondromas. McCune-Albright syndrome is characterized by polyostotic fibrous dysplasia with café-au-lait spots and precocious puberty. Neurofibromatosis can have associated bone lesions but is not associated with chondrosarcomas.

SCC in situ is a low-grade malignancy that typically presents as painless lesions on areas of high sun exposure such as the dorsum of the hand and fingers. The recommended treatment for lesions smaller than 100 mm is wide excision with 4 mm margins to a depth 1 layer below the tumor, along with any adjacent area of induration. Sentinel lymph node biopsy is typically not indicated in the setting of a low-grade tumor such as this one and in the absence of axillary lymphadenopathy.

Langerhans cell histiocytosis or eosinophilic granuloma is a nonneoplastic lesion that is part of a spectrum of clinical diseases featuring histiocytes. Most occur during the first two decades of life within any bone. Radiographs show a radiolucent lesion, frequently diaphyseal in location. A periosteal response is occasionally seen and can resemble more aggressive lesions such as osteomyelitis or Ewing’s sarcoma. Histology demonstrates CD1a positive histiocytes with large oval-shaped nuclei with indentation, and a variable presence of eosinophils.

Discussion: Conventional osteosarcoma most frequently occurs in the second decade, followed by the third decade. Approximately 70% to 75% of patients with osteosarcoma are between the ages of 10 and 25 years. Secondary osteosarcoma (arising in Paget’s disease or radiation-induced) is seen in older adults.

Discussion: The radiographs reveal a blastic lesion of the proximal tibial metaphysis with cortical destruction, mineralization extending into the soft tissue laterally, indistinct margins, and destruction of the normal trabecular pattern. In this age group, with this aggressive appearance, osteosarcoma is the most likely diagnosis.

The images show a complex, lobular lesion of the thigh that has signal characteristics that follow fat. The size of the lesion, the areas of stranding within the mass, along with mild uptake on the gadolinium sequences and the mild edema within the lesion on the T2-weighted image make liposarcoma the most likely diagnosis.

DISCUSSION: Giant cell tumors occur near articular surfaces in young adults. The histology shows abundant giant cells with nuclei resembling the surrounding cells. Although the MRI scan shows soft-tissue involvement, curettage is still the preferred treatment. Chemotherapy is not necessary for benign lesions, and amputation is too aggressive. Cementation, phenol, and cryosurgery (liquid nitrogen) are all acceptable local adjuvants to curettage. Packing the cavity with bone graft rather than cement is also acceptable. REFERENCES: Dahlin DC, Unni KK: Bone Tumors: General Aspects and Data on 8,542 Cases. Springfield, IL, Charles C. Thomas, 1986. Gitelis S, Mallin BA, Piasecki P, Turner F: Intralesional excision compared with en bloc resection for giant cell tumor of bone. J Bone Joint Surg Am 1993;75:1648-1655.

The imaging is characteristic for high-grade osteosarcoma. In patients with osteosarcoma, stage at presentation has the most prognostic impact; clinically detectable metastases at presentation have a very poor prognosis.

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.