Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Demographics, Presentation, and Diagnosis
© 2018 Elsevier Inc. All rights reserved. Please note that the copyright for the original figures submitted by the contributors is owned by Contributors.
Introduction
Chordomas and chondrosarcomas are rare bone cancers. Their estimated combined annual incidence varies from 0.3 to 1.0 every 100,000 persons ; together, they represent less than 1% of all intracranial tumors and 6% of all primary skull base tumors. Chordomas account for approximately 3% of primary bone tumors and 20% of primary spinal tumors ; chondrosarcomas represent approximately 7% of primary bone tumors, and up to 10% of these tumors may occur in the spine. Chordomas and chondrosarcomas constitute a heterogeneous group of neoplasms that share several clinicoradiological similarities but markedly differ regarding their origin, histology, and prognosis.
Chordomas develop from remnants of the primitive notochord and may affect the skull base and any part of the spine. Although McMaster et al. have reported an equal distribution among the sacrum, skull base, and spine, most reports describe an unequal distribution of 50%, 30%, and 20%, respectively. Chordomas may very rarely affect the ribs, lower limbs, and soft tissues.
The origin of chondrosarcomas, on the other hand, remains controversial. During the process of ossification, cartilaginous rests may fail to form bone and remain unchanged in areas of residual endochondral cartilage. These rests may be the progenitors of chondrosarcomas, which may, in fact, develop from any bone that forms from cartilage. Most chondrosarcomas involve the long bones of the appendicular skeleton (e.g., femur, humerus). They may also affect the pelvis, ribs, scapula as well as the skull base, spine, and, rarely, soft tissues. Most chondrosarcomas may be classified according to their location in the bone as primary central, when they arise from the medullar cavity within the bone, or secondary peripheral, when they arise from the surface of the bone as a result of a malignant transformation of a preexisting osteochondroma or enchondroma. Skull base chondrosarcomas are thought to develop from rests of endochondral cartilage near the sphenopetroclival junction, differentiation of pluripotent mesenchymal cells, or metaplasia of mature fibroblasts.
Histologically, conventional chordomas are composed of physaliferous cells, whereas conventional chondrosarcomas have atypical chondrocytes within a hyaline cartilaginous matrix background. Rare subtypes of chordomas (chondroid, sarcomatoid, and dedifferentiated) and chondrosarcomas (clear cell, mesenchymal, and dedifferentiated) display specific histological features. Furthermore, as chordomas arise from notochord remnants, they often stain positively for cytokeratin, whereas chondrosarcomas do not. In recent years, brachyury has also become one of the most important markers for the diagnosis of chordomas (see Chapter 2 ). In terms of prognosis, chondrosarcomas usually carry better outcomes than chordomas (see Chapter 41 ).
Given the importance of distinguishing between these neoplasms for proper management, this chapter will review demographic and clinical data emphasizing their differences.
Demographics
Chordomas
Chordomas may affect people of all ages. Although the median age at diagnosis varies among different studies, a unimodal distribution with a peak incidence around 40–60 years of age is usually reported. Pediatric chordomas are rare, account for less than 5% of the cases, and commonly affect the skull base (see Chapter 36 ). Additionally, skull base chordomas are more common in younger patients (30–40 years), whereas spinal chordomas tend to occur more frequently in older patients (50–60 years).
In terms of gender predilection, it is generally accepted that chordomas have a male predominance, with a ratio of ∼1.5:1. However, the analysis of 400 cases from the Surveillance, Epidemiology and End Results (SEER) database program of the National Cancer Institute of the United States, which evaluated the reported incidence of chordomas in the American population between 1973 and 1995, found that female sex was associated with a greater likelihood of skull base tumors. A female predominance or no gender predilection had also been reported by other authors in more recent surgical series containing solely skull base tumors. Conflicting results were reported in two major pediatric series. Matsumoto et al. have reported a male predominance in a series with 36 pediatric patients, whereas Hoch et al. have reported a female predominance in a series with 73 patients. Last, chordomas are unusual among the African American population.
Chondrosarcomas
Chondrosarcomas may also develop at any age. The analysis of 2890 chondrosarcoma cases from the SEER database program revealed a mean age at the time of diagnosis of 51 years, with the range being 1–102 years, and a male predominance of 1.2:1. However, as the majority of chondrosarcomas enrolled in this analysis arose from the appendicular skeleton (i.e., limbs), these data do not necessarily reflect the demographic peculiarities of chondrosarcomas arising from the axial skeleton (i.e., skull base and spine).
Although the mean age at the time of diagnosis also varies among different studies, skull base chondrosarcomas usually present at younger ages compared with chordomas, with a peak incidence around 20–40 years. Spinal chondrosarcomas, as do spinal chordomas, more often occur in older patients, with a peak incidence around 40–60 years reported in major series. Pediatric chondrosarcomas account for less than 10% of all cases.
Chondrosarcomas of the appendicular skeleton are more common in men than in women. Although most series of skull base tumors have a male to female ratio of ∼2:1, a minority report a slight female predominance or no sex difference. Chondrosarcomas are also unusual in the African American population.
In summary, there are no major demographic differences between patients with chordomas and those with chondrosarcomas. People of all ages may be affected by either tumor, although chondrosarcomas and skull base tumors in general tend to occur at earlier ages and chordomas and spinal tumors in general have a predilection for older patients. Reported findings regarding gender predilection for chordomas and condrosarcomas are mixed, but a male predominance is most commonly reported. Last, both tumors are relatively rare in African Americans.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here