Background Flashcards
What is the most common subtype of chondrosarcoma?
Conventional chondrosarcoma constitutes 85% of chondrosarcomas, 90% of which are low-intermediate grade. The WHO 2013 classification system has reclassified grade 1 conventional chondrosarcoma as an atypical cartilaginous tumor/chondrosarcoma grade I (ACT /CS1). Grades 2 and 3 conventional chondrosarcomas are classified as malignant due to metastatic potential.
What are some other subtypes of chondrosarcoma?
Dedifferentiated (10%), mesenchymal (<2%), and clear cell (<2%) are other chondrosarcoma subtypes, classified under the category of malignant by WHO. Dedifferentiated and mesenchymal are high grade. Clear cell is low grade.
How are conventional chondrosarcomas further subdivided?
Conventional chondrosarcomas are further classified by their location in bone. ∼75% of all chondrosarcomas are central chondrosarcomas, based on their location in the medullary cavity. The majority are thought to arise primarily (i.e., without a benign precursor lesion). Peripheral chondrosarcomas, by definition, arise by the malignant transformation of a pre-existing benign osteochondroma in the cartilage cap.
What is the typical grade of a conventional secondary chondrosarcoma?
Typically high grade. Conventional primary central chondrosarcoma can vary in grade from low to high.
Chondrosarcoma accounts for what % of primary bone tumors?
Chondrosarcoma accounts for ∼30% of primary bone tumors (behind osteosarcoma and multiple myeloma).
Which subtypes occur in older adults? Which subtypes present in younger pts?
Dedifferentiated, conventional primary central, and conventional secondary peripheral chondrosarcoma typically present in older pts. Clear cell and mesenchymal chondrosarcoma can present in any age, but peak incidence occurs in younger adults. Periosteal chondrosarcoma in adults in their 20s and 30s.
What 2 benign precursor lesions may give rise to conventional chondrosarcoma?
Osteochondroma, majority in the long bones, is a precursor lesion for conventional secondary peripheral chondrosarcoma. Enchondromas develop in the medulla of the bone, and are hypothesized to be a precursor lesion in up to 40% of conventional central chondrosarcoma, with the highest risk in pelvis.
What are the most common locations for conventional primary chondrosarcomas?
Most chondrosarcomas (∼75%) arise in the proximal femur, pelvis, or proximal humerus.
Chondrosarcomas of the skull base typically arise from what structures?
Although chondrosarcomas of the skull base may arise from the clivus, most originate laterally from the spheno-occipital junction or less commonly from the sphenoethmoid complex.
What is the typical pattern of spread for chondrosarcoma of the skull base?
Chondrosarcomas of the skull base are locally aggressive and may expand, destroying bone and compressing adjacent tissues.
What other tumor may often be mistaken for chondrosarcoma at the skull base? How can they be distinguished histologically?
Chordoma (particularly the chondroid variant) may appear similar to chondrosarcoma. Chordoma typically show positivity for epithelial membrane antigen (EMA) and pan-cytokeratin (panCK); whereas chondrosarcoma is positive for D2–40.
What are the common presenting Sx associated with chondrosarcoma?
Conventional chondrosarcoma often presents with pain of insidious onset and progressive chronology and localized swelling.
