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Year |
2001 |
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Question Number |
134 |
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Category |
Select |
Question
A 42-year-old woman has had low-grade aching pain in her forearm for the past 4 years recently fell on the arm and now reports markedly increased pain. A plain radiograph and biopsy specimen are shown in Figures 41A and 41B. What is the most likely diagnosis?
1- Chondroblastoma
2- Chondrosarcoma
3- Chondromyxoid fibroma
4- Adamantinoma
5- Enchondroma
Figures
Answer (click for answer)
Answer 2, Chondroblastoma is a rare benign tumor that usually occurs in the Age range of 15-25. It is most commonly seen as a well-circumscribed Lytic lesion that, when in long bones, involves the epiphysis. About 50% of them extend into the metaphysis, this is usually only seen when the growth plates are closed. Histologically, they are composed of sheets of stromal cells, scattered multinucleated giant cells, and varying amounts of chondroid matrix. The nuclei often have a "fried egg" appearance Chondromyxoid fibroma, like chondroblastoma, is characterized by incomplete cartilage differentiation, but when found in long bones, always occurs in the metaphysis or metadiaphysis. They usually occur in patients < 35, when in long bones they generally about one cortex, are well circumscribed and often have sclerotic margins, and rarely have intralesional calcifications. Both of these are benign, and very slow growing.
Adamantinoma are low-grade malignant neoplasms, most commonly found in the midshaft tibia. Patients range in age from 3 to 72, but most are in there 20’s and 30’s. Patients usually complain of pain and swelling, often of long duration. Generally they are cortical based lesions, which show multiloculated lytic areas surrounded by dense reactive bone. Often, the lesion appears multifocal and involves long segments of the tibial shaft, and in 10% of cases there is involvement of the soft tissues. Histologically, they consist of various patterns of epithelial cells in a fibrous and fibroosseous stroma. Enchondroma are extremely common hyaline cartilage tumors. They more commonly involve the tubular bones of the hands and feet, and are the most common bone tumor of the hand. They appear as cartilaginous islands in the medullary canals of bones, which cease to grow in adulthood. In adults they are usually asymptomatic, and are discovered incidentally on radiographs or bone scans done for other reasons. Large enchondromas or enchondromas in the hand, however, may produce pain from a stress fracture. Radiographically, in young patients, they are well-defined lytic lesions in the central portion of the metaphysis or metadiaphysis. As patients age, the normally radiolucent cartilage begins to calcify and ossify, leading to the characteristic appearance of radio dense rings and stipples.
Chondrosarcomas are malignant cartilage neoplasms that do not synthesize osteoid. After osteosarcoma, it is the second most common primary malignant bone tumor. It tends to occur in older patients and most often involves the axial skeleton. They are generally divided into central and surface types, and show a wide range of aggressiveness, based on their histologic grade. Some lesions, although locally aggressive, grow slowly and rarely metastasize. By contrast, others are very destructive and metastasize readily. Fortunately, most (about 75%) grow slowly. They are generally grouped into three histologic grades, 1-3, with 3 being the worst. Grade I tumors are slow growing, have small, dark nuclei and scant cytoplasm. Grade II have larger, paler nuclei, mild nuclear pleomorphism, and more abundant cytoplasm. Grade III are high-grade and contain large vesicular nuclei that often have prominent nucleoli. The cytoplasm is abundant; spindle cells as well as mitotic figures are often present. Central chondrosarcomas are most often seen in patients in there 40’s and 50’s. High-grade lesions usually present with worsening pain. Radiographically, ring-shaped and stippled calcifications are irregularly distributed in the medullary canal, and the boundaries cannot usually be traced with a continuous line. Cortical erosion or expansion also occurs; sometimes the cortex is thickened, which is a sign of permeative intracortical growth. Low-grade types pose a diagnostic dilemma, as they can be confused with enchondromas. They can however be distinguished by the presence or absence of growth in adults, as endchondromas typically cease growth with maturity. Also the presence of absence of pain, as pain is an important indicator of growth. However, one must be certain that the pain is coming from growth of the tumor and not some other unrelated cause. Histologically chondrosarcomas exhibit permeation of the bone marrow by cartilage and fibrous bands separate lobules of cartilage. Enchondromas on the other hand, have lobules that are separated by bone marrow or endchondral bone.
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