10. Pathology and Oncology MCQs

DISCUSSION: 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.REFERENCES: Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors.  Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 364.Mirels H: Metastatic disease in long bones: A proposed scoring system for diagnosing impending pathologic fractures.  Clin Orthop 1989;249:256-264.

DISCUSSION: The MRI scan shows plantar fibromatosis.  The treatment is usually nonsurgical.If surgery is indicated, wide local excision with excision of the entire plantar fascia is usually indicated.  The main problem with simple excision of the lesion is the high chance of recurrence.  The other listed complications are those that are a result of the wide local excision.REFERENCES: Aluisio FV, Mair SD, Hall RL: Plantar fibromatosis: Treatment of primary and recurrent lesions and factors associated with recurrence.  Foot Ankle Int 1996;17:672-678.Bos GD, Esther RJ, Woll TS: Foot tumors: Diagnosis and treatment.  J Am Acad Orthop Surg 2002;10:259-270.

DISCUSSION: Radiation therapy is commonly used as an adjuvant in the treatment of soft-tissue sarcomas, but a controversy exists whether it should be preoperative or postoperative.  Radiation therapy can be given prior to or following resection of the tumor.  Postoperative radiation is usually given in a higher dose to a larger treatment field.  This commonly results in a higher incidence of fibrosis and lymphedema.  There is no statistical difference in local recurrence rate between the two radiation treatment plans.  Neuropathy is more commonly a complication of chemotherapy.  Preoperative radiation therapy has been shown to have a higher wound complication rate than postoperative radiation.REFERENCES: Vaccaro AR (ed): Orthopaedic Knowledge Update 8.  Rosemont, IL, American Academy of Orthopaedic Surgeons, 2005, pp 197-215.Davis AM, O’Sullivan B, Turcotte R, et al: Late radiation morbidity following randomization to preoperative versus postoperative radiotherapy in extremity soft tissue sarcoma.  Radiother Oncol 2005;75:48-53.

The age, imaging and histology are consistent with an osteosarcoma. The radiograph shows an aggressive (lytic, mottled, sclerotic) appearing lesion around the distal femur metadiaphyseal region. The T2 weighted MRI image shows a significant soft tissue mass which appears to arise from the distal femur with destruction of the adjacent cortex. The biopsy shows an infiltrative pattern with elements of osteoid and bone.Treatment for osteosarcoma includes neoadjuvant chemotherapy, wide resection, and adjuvant chemotherapy.

DISCUSSION: The CT scan shows an osteoblastic nidus pathognomonic for an osteoid osteoma. Surgical treatment should include an en bloc excision of the lesion. Surgical treatment is not mandatory because the lesion often becomes asymptomatic over time. This lesion is not amenable to radiofrequency ablation due to its proximity to the spinal cord. A complete corpectomy is not necessary to adequately resect the lesion, as only the nidus needs to be removed. Radiation therapy and antibiotics are not appropriate treatments for an osteoid osteoma. Posterior C2-C3 fusion will not address the pathology. REFERENCES: Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 351-366. Hadjipavlou AG, Lander PH, Marchesi D, et al: Minimally invasive surgery for ablation of osteoid osteoma of the spine. Spine 2003;28:E472-E477.

The patient has a pelvic chondrosarcoma. The radiograph shows a lytic bone lesion emanating from the left inferior pubic ramus and extending into the soft tissues. Punctate calcifications are revealed on the radiograph and CT scan. The histology is consistent with a malignant cartilage lesion. Appropriate treatment for a pelvic chondrosarcoma is wide resection. In this location, wide resection of the ischiopelvic region (type 3 internal hemipelvectomy) is the treatment of choice. A type 2 internal hemipelvectomy involves resection of the periacetabular region. A type 1 internal hemipelvectomy involves resection of the ilium. No reconstruction is required for a type 3 resection. A classic hemipelvectomy is not necessary because the tumor can be removed with an adequate margin while maintaining the neurovascular structures and hip joint.

Treatment of patients with unplanned excision of soft-tissue sarcomas is challenging. If the margins are positive or unclear, the patient is best managed with repeat excision of the tumor bed, and radiation therapy if the repeat excision does not yield wide margins. In patients with no detectable tumor on physical examination or imaging after unplanned excision, some studies have shown that up to 35% of patients will have residual disease and a poorer local recurrence rate (22% versus 7%). Therefore, whenever feasible, a reexcision of the tumor bed is recommended.

Patients with a metastatic lung carcinoma are best staged and imaged with a PET scan. Although many tumors are clinically evaluated with PET scans, metastatic lung cancer is one of the few “approved” indications for PET imaging. This imaging modality is sensitive for delineating the extent of disease and helpful for identifying areas that may also be at risk for pathologic fracture. Stabilization of painful, lytic lesions in weight-bearing bones is recommended to prevent pathologic fracture. Stabilization of an impending pathologic fracture is generally easier than stabilization of a pathologic fracture; once the patient in this vignette sustains a fracture, resection and reconstruction is indicated because stabilization alone is unlikely to heal and poses high risk for failure. In cases of extreme bone loss, especially in the epiphyseal region, reconstruction with tumor megaprostheses is desirable to avoid mechanical failure of additional internal fixation. Patients with widely metastatic disease may not be able to use ambulatory assistance aids effectively, placing traditional internal fixation at risk for failure. Use of megaprostheses obviates the need for adjuvant therapies to correct the loss of bone stock. Radiation therapy alone to lesions that are radiosensitive is effective but does not alleviate the risk for pathologic fracture. Chemotherapy alone is insufficient treatment for bone metastases. Hormonal therapy is acceptable for treatment of hormone-sensitive tumors; however, is not sufficient treatment for an impending pathologic fracture. For patients with remote diagnoses of carcinoma, biopsy of new-onset presumed metastases is mandatory to avoid an incorrect treatment regimen being employed. Patients can develop a secondary malignancy or infection, both of which will require a different treatment regimen. Biopsy should be done and diagnosis established either preoperatively or intraoperatively prior to instrumentation (with frozen section analysis) to avoid contamination of the femoral canal and soft-tissue envelope. Sending a specimen after instrumenting the femur or after surgery contaminates the femur if a sarcoma is diagnosed and lessens the likelihood of limb salvage.

Any large (greater than 5 cm), deep, heterogeneous mass in the extremities should be considered a sarcoma until proven otherwise. Needle biopsies can obtain sufficient tissue for diagnosis and are associated with less morbidity than open biopsy. Marginal resections or excisional biopsies should be reserved for a few select benign lesions and locations.

Upon review of the radiograph in fig. 63 it has the appearance of a classic Unicameral Bone Cyst of the proximal humerus of a skeletally immature individual. Also noted is a nondisplaced fracture of proximal humerus through the cyst. The article above gives accepted treatment protocols for unicameral bone cysts:Radiographically Active Cyst (age 4 to 8 years old with pathologic fracture)Align and immobilizeObserve for spontaneous healingReassess after 2 to 4 months and if recurrent, follow procedure for pathological fracture of radiographically active cysts described in the article above.

The radiographs show a well-defined, irregular, eccentric lesion in the distal tibia metaphysis with a thin sclerotic margin. The radiographs are diagnostic of nonossifying fibroma, a common entity in this age group and in this location. No further work-up is indicated. The patient was asymptomatic prior to the injury and the lesion is small and thus not worrisome for an impending pathologic fracture; therefore, no treatment is indicated beyond observation. The natural history of these lesions is to gradually ossify as the patient reaches skeletal maturity.

The clinical presentation is consistent with a symptomatic pedunculated osteochondroma. The next most appropriate step is marginal resection. Osteochondromas are benign lesions, and treatment is dictated by the severity of symptoms, skeletal maturity, and concern for malignant transformation. In symptomatic patients, marginal excision is the treatment of choice.

The imaging shows an aneurysmal bone cyst with a destructive, eccentric metaphyseal lesion with fluid-fluid levels on MR imaging. The described histology confirms this. The appropriate treatment is extended intralesional curettage.

In nearly 50% of patients with a unicameral bone cyst, the lesion remains asymptomatic until a fracture occurs, usually as the result of relatively minor trauma. If the lesion expands, the bone is weakened and may cause pain. Fibrous cortical defects are usually an incidental finding and typically asymptomatic. Malignant bone tumors such as osteosarcoma and Ewing’s sarcoma most commonly cause pain, and pathologic fracture occurs in less than 10% of patients. Giant cell tumors are uncommon in children and usually are painful.

In an adult with an anterior cortical tibial lesion, this is the classic histologic appearance and anatomic location for an adamantinoma. The histology reveals areas of epithelial cells (in a glandular pattern) within a fibrous stroma. The epithelial cells are shown in nests. They would stain positively for keratin. Adamantinoma is a rare malignant bone tumor with a propensity for late metastasis. It has a high incidence of local recurrence unless resected with a wide margin. Chemotherapy and radiation therapy are not helpful in the treatment of this disease. Amputation generally is not necessary because a diaphyseal resection is usually possible.

A mucous cyst is thought to be a ganglion arising from the DIP joint in patients with osteoarthritis. They are frequently associated with nail deformities. Treatment involves removal of the cyst with debridement of DIP joint osteophytes.

DISCUSSION: Surgical curettage or en bloc resection is the treatment of choice for osteoid osteoma. Night pain and relief of symptoms with nonsteroidal anti-inflammatory drugs are classic findings for osteoid osteoma. REFERENCES: Donley BG, Philbin T, Rosenberg GA, Schils JP, Recht M: Percutaneous CT guided resection of osteoid osteoma of the tibial plafond. Foot Ankle Int 2000;21:596-598. Kenzora JE, Abrams RC: Problems encountered in the diagnosis and treatment of osteoid osteoma of the talus. Foot Ankle 1981;2:172-178. Shereff MJ, Cullivan WT, Johnson KA: Osteoid-osteoma of the foot. J Bone Joint Surg Am 1983;65:638-641.

DISCUSSION: The presence of a painless soft-tissue mass that is greater than 5 cm and deep to the fascia should be considered a soft-tissue sarcoma until proven otherwise. The diagnosis of a hematoma should be made with great caution because the absence of a history of trauma, pain, or presence of ecchymosis makes it unlikely. A diagnosis of pyomyositis is unlikely because of the absence of warmth, erythema, or adenopathy. The MRI scans are not consistent with lipoma or hemangioma. The MRI signal characteristics of a lipoma should be the same as subcutaneous fat on all sequences. Soft-tissue hemangiomas are not well defined and have an infiltrative appearance on MRI scans, as does pyomyositis.

DISCUSSION: Distant bone metastasis is associated with an extremely poor prognosis for patients with osteosarcoma (5-year survival rate of less than 10%). Most osteosarcomas are high grade and extracompartmental, and approximately half are greater than 8 cm at presentation. The 5-year survival rate for these patients is approximately 70%. Patients with a solitary pulmonary metastasis have a prognosis worse than patients without detectable metastases but not as bad as those with bone metastases. REFERENCES: Bielack SS, Kempf-Bielack B, Delling G, et al: Prognostic factors in high-grade osteosarcoma of the extremities or trunk: An analysis of 1,702 patients treated on neoadjuvant cooperative osteosarcoma study group protocols. J Clin Oncol 2002;20:776-790. Heck RK, Stacy GS, Flaherty MJ, et al: A comparison study of staging systems for bone sarcomas. Clin Orthop Relat Res 2003;415:64-71. Kager L, Zoubeck A, Potschger U, et al: Primary metastatic osteosarcoma: Presentation and outcome of patients treated on neoadjuvant Cooperative Osteosarcoma Study Group protocols. J Clin Oncol 2003;21:2011-2018.