Critical clinical and radiological features that distinguish a benign enchondroma from a malignant chondrosarcoma

One common type of malpractice concerns the failure of a clinician or radiologist to properly diagnose a patient’s musculoskeletal tumor based on the relevant clinical and radiological features. One sub-type of these musculoskeletal tumors is a cartilage tumor, a tumor that grows within a human bone.

Musculoskeletal tumors are benign or malignant lesions that form in human bone and the connective tissues. Cartilage tumors are musculoskeletal tumors that produce cartilage inside the host bone. There are only two types of cartilage tumors: enchondroma (benign) and chondrosarcoma (malignant). Cartilage tumors range in severity from benign enchondroma to low-grade malignant chondrosarcoma to high grade chondrosarcoma. Chondrosarcoma is the second most common primary malignant bone tumor, accounting for 25-30% of all primary bony malignancies.

Several well-established clinical guideposts and principles exist regarding location, size, presence and duration of pain, and age of the patient, that assist physicians in distinguishing a benign enchondroma from a low-grade malignant chondrosarcoma. Clinically, benign enchondromas most commonly involve the tubular bones of the hands and feet. When present in long bones, such as the femur, enchondromas most often are located in the distal femur (furthest from the hip). Enchondromas are usually asymptomatic; i.e., with no associated pain, and therefore, the vast majority are discovered incidentally on radiographs or bone scans done for other reasons. The majority of enchondromas are approximately 3 cm in maximum dimension. Benign tumors larger than 5 cm in maximum dimension are extremely rare. In contrast, chondrosarcomas are most commonly located in the proximal femur (closest to the hip) and pelvis. Like other malignant tumors, the single most common clinical symptom for chondrosarcoma is the presentation with pain that is directly referable to the bone in which the tumor is growing. Published literature indicates that the pain is typically present for 1-2 years prior to diagnosis and is most often described by patients as an insidious or achy pain that is initially constant in nature, but that ultimately progresses in severity. Generally, patients with chondrosarcoma are over the age of 40, while those with benign enchondroma are typically under the age of 40.

Radiographs are crucial in distinguishing between benign enchondroma and low-grade chondrosarcoma. Perhaps the single most important radiographic feature for a cartilage tumor is whether the tumor is confined to the inside of the bone or has grown outside of it. The radiologic hallmark of a chondrosarcoma is evidence of the tumor breaking through the cortex (outer shell) of the bone and extending into the soft tissues surrounding the bone. This is often referred to as “cortical extension” leading to a “soft tissue mass.” Importantly, benign enchondromas simply do not break through the bone’s cortex, but rather, remain well circumscribed within the bone. The best radiologic modality for evaluating whether cortical breakthrough/extension has occurred is an MRI. A second common radiographic feature of chondrosarcoma that can be visualized best on an MRI is when the tumor appears heterogenous in signal intensity (a number of different structural variations) as opposed to homogenous (multiple identical structures), a feature that is more consistent with a benign enchondroma.

The CT scan is the next best modality used to distinguish between an enchondroma and chondrosarcoma. In contrast to the MRI, which is most useful at detecting the presence of a soft tissue mass, CT scans are particularly useful at evaluating the integrity of the bone’s cortex. Because enchondromas never break through the bone’s cortex, a CT image of an enchondroma is expected to have an intact rind of cortical bone surrounding it. To the extent that cortical irregularity or cortical erosion is observed, this is considered strong evidence of malignancy/chondrosarcoma. Lastly, in some instances, cartilage tumors can be observed on plain x-rays. To the extent that a malignant tumor has broken through the bone, clinicians can, in some instances, observe areas of calcification outside the bone in the area of cortical breakthrough.

At STSW, our attorneys have successfully handled cases involving a physician’s failure to properly diagnose a patient with a malignant cartilage tumor, e.g. a chondrosarcoma. If you or a loved one believe that you have been the victim of a missed or untimely diagnosis of a malignant musculoskeletal or soft tissue tumor of any kind, call the lawyers at STSW for a free consultation at 410-385-2225.

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