Bone Tumors

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Bone tumors are generally classified according to the matrix that their constituent cells produce: eg, tumors that produce a cartilaginous matrix are classified as chondrosarcomas, those that produce osteoid are classified as osteosarcomas and others that lack a distinct matrix may be classified as fibrosarcomas. Chondrosarcomas and osteosarco-mas are by far the most common sarcomas involving the facial skeleton, but other rarer types such as Ewing's sarcoma and peripheral primitive neuroectodermal tumor (pPNET), malignant fibrous histiocytoma (MFH), vasoformative tumors such as angiosarcoma, and chordoma are also found.

Chondrosarcomas (CS) are a heterogeneous group of malignant tumors of cartilaginous origin. At the Memorial Sloan-Kettering Cancer Center (MSKCC), only 28 (5%) of 557 chondrosarcomas involved the head and neck.42 Young males in the third or fourth decades of life are more commonly affected and the maxilla, cervical vertebrae and mandible are the most frequently involved sites (Figure 17-3). Most patients present with a painless swelling but there may be other site-specific symptoms. The pathologic spectrum ranges from a well-differentiated benign-looking cartilaginous tumor to a high-grade aggressive malignancy. Except for CS of the larynx that are known to be well-differentiated, slow-growing, localized tumors, the anatomic site of origin does not impact on the outcome. Surgical excision with histo-logically clear margins is the most effective treatment, and adjuvant radiotherapy may be added as indicated.

Orbital Cancer Invasion
Figure 17-3. A, Coronal MRI appearance of a large chondrosarcoma of the right maxilla. B, Axial section demonstrating tumor invasion into the orbit.

Aggressive treatment of local failures is warranted because the median interval between recurrence and death is 2 years. The reported survival rates range from 44 to 81 percent. Distant metastases occur infrequently and the most common cause of death is local recurrence that invades the base of the skull.

Osteosarcoma (OS) is a tumor composed of malignant spindle-shaped or round cells that produce osteoid or primitive bone and they are generally classified according to the pattern of proliferation of their malignant cells (Table 17-3). Approximately 7 percent of 1,095 patients treated for OS at MSKCC between 1921 and 1979 had tumors involving the craniofacial bones.43 Osteosarcomas of the jaws arise in older patients and tend to metastasize later in their natural course compared to OS of the long bones. The mandible (49%) is more frequently affected than the maxilla (37%), while other extragnathic bones are less commonly involved (14%).44 Within the head and neck, the histologic distribution varies according to the site of the tumor.47 Most OS of the head and neck are high-grade tumors but some lesions such as periosteal and juxtacortical OS may be of low grade. Local pain is a common symptom that leads to the patient seeking dental treatment, and a jaw lesion may be discovered subsequent to dental extraction. Radio-logically (Figure 17-4), most OS tend to be osteolytic except those of the mandible where about 50 percent are osteoblastic.45 Computed tomography, which is the imaging modality in routine use, reliably demonstrates calcification and cortical involvement, but MRI is more effective in detecting intramedullary and extraosseous soft-tissue extension. Unlike extremity

Table 17-3. THE CLASSIFICATION OF OSTEOSARCOMAS

Conventional osteosarcomas Osteoblastic Chondroblastic Fibroblastic Epithelioid Giant cell Small cell osteosarcoma Telangiectatic osteosarcoma Parosteal osteosarcoma Periosteal osteosarcoma Juxtacortical osteosarcoma High grade Low grade Secondary osteosarcoma Radiation-induced Paget's sarcoma

Bone Tumor Mandible

Figure 17-4. A, Clinical appearance of a patient presenting with an osteosarcoma of the left mandible. B, Panorex clearly demonstrating that the lesion was considerably more extensive than appreciated clinically. C, Complete surgical excision necessitated a total mandibulectomy and cut section of the specimen validated the radi-ologic findings.

Figure 17-4. A, Clinical appearance of a patient presenting with an osteosarcoma of the left mandible. B, Panorex clearly demonstrating that the lesion was considerably more extensive than appreciated clinically. C, Complete surgical excision necessitated a total mandibulectomy and cut section of the specimen validated the radi-ologic findings.

OS, there is currently no data from randomized controlled trials on the role of chemotherapy in treatment of OS of the head and neck, but 2 meta-analyses based on nonrandomized published data have reported conflicting conclusions.43,46 Adequate surgical resection remains the mainstay of treatment and adjuvant chemotherapy and/or radiation may be considered in appropriate situations. Osteosarcoma of the extragnathic craniofacial bones47 and those arising in the background of Paget's disease48 are generally associated with a poorer outcome. Although the overall 5-year survival of patients with head and neck OS was only 37 percent in a meta-analysis of 173 patients,43 smaller individual series have reported better survival of up to 59 percent at 10 years.49,50 Recurrences are usually local, but distant metastases, most commonly pulmonary, have been reported in 30 to 50 percent of patients.51

Ewing's sarcoma/peripheral primitive neuroectodermal tumor are now thought to represent a spectrum of tumors arising from the primitive neuroectoderm and characterized not only by certain common ultrastructural findings but also by a specific genetic translocation t(11;22) (q24; q11.2-12).52 Immumohis-tochemical and cytogenetic studies are useful in distinguishing these tumors from other "small, blue, round cell tumors." Ewing's sarcoma of the jaw more commonly involves the mandible and most often presents with pain and swelling. It tends to affect individuals in their teens and seems to have no predilection for either sex. Imaging shows an osteolytic lesion but the classic "onion peel" appearance due to periosteal reaction is rarely seen. Ewing's sarcoma is considered a systemic disease even if only a single lesion is demonstrable, and treatment consists of multimodality treatment including chemotherapy, surgery and radiation. This approach has improved the 5-year survival of patients from around 15 percent to 74 percent.53

Odontogenic cysts (Table 17-4) and tumors (Table 17-5) arise from the teeth-producing tissue or its remnants and comprise a wide spectrum of lesions (see Chapter 2). Both ectodermal and mesenchymal odontogenic tissues can undergo neoplastic change giving rise to a myriad of lesions. The diverse clinical behavior of these tumors can generally be predicted by their histologic appearance. Therefore, adequate biopsy must be undertaken and the precise

Table 17-4. THE MSKCC STAGING SYSTEM FOR SOFT TISSUE SARCOMAS

Factors

Favorable

Unfavorable

Size < 5 cm > 5 cm

Depth

Superficial

Deep

Graue Low yiaue niyn yiaue

Good differentiation

Poor differentiation

Hypocellularity

Hypercellularity

Dense stroma Hypovascular

Minimal stroma Hypervascular

< ^ mitnQpQ /

Significant necrosis

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10 high-power fields

10 high-power fields

Stage Grouping

Stage O Stage I Stage II Stage III

2 favorable signs

1 unfavorable sign 1 favorable, 2 unfavorable signs

3 unfavorable signs

Data from Hajdu S, et al. The role of the pathologist in the management of soft tissue sarcomas. World J Surg 1988;12:326-31.

Distant metastasis

Data from Hajdu S, et al. The role of the pathologist in the management of soft tissue sarcomas. World J Surg 1988;12:326-31.

histologic diagnosis of the lesion must be used to guide treatment. Tumors at the benign end of the spectrum such as ameloblastic fibromas, ameloblas-tic fibro-odontomas and cementoblastomas may be treated by enucleation with or without curettage. More aggressive lesions such as ameloblastoma, calcifying epithelial odontogenic tumor and ameloblastic odontoma require wider margins of excision while malignant tumors may require adjuvant treatment in addition to radical surgery.

Ameloblastomas are among the most common odontogenic tumors and are thought to arise from either the remnants of the dental lamina, the enamel organ or basal cells of the surface epithelium. They can also originate in the epithelium of odontogenic cysts such as dentigerous cysts. The mean age at diagnosis is about 38 years and there seems to be no predilection for either sex.54 The mandible is more commonly affected than the maxilla, and most tumors

Table 17-5. ODONTOGENIC CYSTS OF THE JAWS

Periapical or radicular cyst Residual cyst Lateral periodontal cyst Glandular odontogenic cyst Dentigerous cyst Odontogenic keratocyst Calcifying odontogenic cyst arise in a posterior location. Early lesions remain asymptomatic and may be incidentally picked up on dental radiographs as a radiolucency without any calcified components. However, most patients present with a slow-growing, painless swelling that may be associated with loose teeth, malocclusion, or ill-fitting dentures. Radiologically, the lesion may be either unilocular or multilocular (Figure 17-5). Conventional ameloblastomas have a tendency to infiltrate the bony trabeculae so that enucleation or curettage is associated with high failure rates.55 Radical surgical resection is associated with a recurrence rate of only 4.5 percent while enucleation and curettage fails in as many as 59 percent and radiotherapy in 42 percent of cases.56 Malignant odontogenic tumors are rare and may arise in one of three settings: (1) conventional ameloblastoma without cytologic features of malignancy that is designated malignant ameloblastoma because of histologically documented distant metastasis of well-differentiated ameloblastoma, (2) malig-

Figure 17-5. A, Panorex of the mandible showing a loculate lesion of the posterior aspect of the body of the right hemimandible. B, The extent of involvement of the bony trabeculae is clearly evident on this radiograph of the segmental mandibulectomy specimen.

nant transformation of ameloblastoma with features of poorly differentiated carcinoma, ameloblastic carcinoma, and (3) primary intra-alveolar carcinoma that is thought to develop from residual odontogenic epithelium within the jaws so that it exhibits features of squamous cell carcinoma without any continuity with the surface epithelium. Malignant ameloblas-tomas almost always involve the mandible and have been reported to metastasize to lungs (75%) and lymph nodes (15%) with a median post-treatment disease-free interval of 9 years.57 Ameloblastic carcinoma signifies the presence of poorly-differentiated elements within a primary well-differentiated ameloblastoma and/or its metastases. Most tumors involve the mandible and metastasize to the lungs, lymph nodes, liver or bones, and most patients with dedifferentiated tumors succumb to their disease within 2 years of detection of metastases.58

Primary intraosseous carcinoma is an aggressive disease that is best treated like squamous carcinoma of the oral cavity that has invaded bone. Surgical resection of malignant odontogenic tumors may need to be combined with radiation therapy for locoregional control and chemotherapy with or without radiation therapy may be necessary for management of distant metastases.

Metastatic tumors are usually diagnosed in patients between 50 and 70 years of age. The most common site of the primary in women is the breast followed by the adrenal, colon, female genital tract and thyroid. In men, the most common primary site is the lung followed by prostate, kidney, bone and adrenal gland. The mandible is the most commonly involved bone and about a third of patients present with an oral lesion as the first sign of their malignancy.59

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