R. Lor Randall, MD, FACS Despite being considered a rare, noncancerous bone tumor, chondrosarcoma often necessitates aggressive treatment due to its potential for metastasizing. Accordingly, it is vital to confidently differentiate patients with chondrosarcoma from those with bone malignancies in clinic, particularly when it comes to atypical disease presentations, says R. Lor Randall, MD, FACS. “We’re talking about an uncommon tumor with [some] uncommon presentations. It’s something that doesn’t get a lot of attention in the oncology world but might be [a condition] that people should know about,” said Randall, the David Linn Endowed Chair for Orthopedic Surgery, the chair of the Department of Orthopedic Surgery, and a professor at UC Davis Comprehensive Cancer Center in Sacramento, California. In an interview with OncLive®, Randall explained the difference between noncancerous chondroblastoma and other bone neoplasms, detailed the typical diagnosis and treatment of this rare condition, and emphasized the importance of pediatric and medical oncologists being able to identify it in clinic. OncLive: What is chondroblastoma, and how does it differ from other hematologic malignancies? Randall: Chondroblastoma is not a malignancy. It’s a benign tumor of the bone usually in young people, but it can mimic an aggressive bone neoplasm in appearance. Chondroblastoma is a somewhat aggressive benign neoplasm of bone, meaning it must be treated aggressively with surgery sometimes; however, radiographically and imaging-wise, it could be confused for something like a bone malignancy. It is possible that medical oncologists or other types of oncologists beyond orthopedic oncologists might see someone with a potential chondroblastoma. It’s important to realize that these are very rare [neoplasms], and they make up less than 1% of all bone tumors. They tend to [present] in young people and tend to [occur] in the epiphysis or apophysis of a skeletally immature person. How is chondroblastoma typically diagnosed? The workup usually [involves] referral to an orthopedic oncologist, who in their expertise will probably be able to determine whether this is a chondroblastoma and then treated surgically. A very small number of patients can go on to develop recurrences in the same area, and there have been some sparse case reports of it spreading in a benign way to the lungs. We’ve recently published a couple of papers [on unusual chondroblastoma cases]. One was [published] by me [and detailed an incidence of] chondroblastoma that was recurrent in the pelvis of an older person. [This was] unusual in that it’s [in an] older [person] and [located] in the pelvis. My partner [published a case study of] one in the finger, and it’s not very common in the finger. Why is chondroblastoma more frequently observed in younger patients? We don’t know the medical answer to that, per se, but we think it probably has to do with the fact that these patients are skeletally immature, and their growth plate is very active. There might be some sort of inclusion cyst of the growth plate in the epiphysis leading to this sort of satellite area in the bone. What is the typical management approach for this condition? Does the treatment of chondroblastoma differ when dealing withunusual presentations? Generally speaking, they’re treated with surgical removal, and there’s different ways by which that is done. They tend to arise in anatomically-challenging areas, [particularly] between a joint and a growth plate where there’s not a lot of room for error. You don’t want to create any damage to the growth plate or to the joint, and you have to be very strategic and precise in how you go after these. It does lend itself to management with techniques such as surgical navigation, computerized navigation, and other techniques that have come online in the past 5 to 10 years. [These] enable the surgeon to be much more precise in their surgical ablation of [chondroblastomas]. Given the rarity of this condition, can chondroblastoma mimic any other conditions? Because chondroblastomas evolve in a very distinct part of the bone in a young person, the differential diagnosis is relatively limited. If it arises in an adult or it’s very advanced, things like osteosarcoma, Ewing sarcoma, and other types of bone sarcomas would be in the differential diagnosis. At this time, is there any ongoing or planned research focused on chondroblastoma? There may be some research on applied surgical techniques. Although we don’t understand the entire pathophysiology [of chondroblastoma], it’s rare and treatable enough that there’s not a lot of laboratory research going into it. Because of its anatomic location, many surgical oncologists, particularly orthopedic oncologists, are using some of the latest applications in technology to treat these in that scenario of investigation. What is your main takeaway message for academic and community oncologists who might not see this condition very often? Particularly for the pediatric oncologists, if they are seeing someone with a destructive lesion in the bone that is in the epiphysis, which is the area right underneath the joint space, they should [consider] chondroblastoma. Obviously, they’ll confer with the radiologists and orthopedic oncologists, but it is something to consider.If [they are] referred a patient with a destructive lesion in this area, they should be able to counsel patients that there are benign things that can look like this, as chondroblastoma is benign. [They can tell these patients] not to be too alarmed, but that we must establish the diagnosis. In the grand scheme of things, there are very rare case reports of chondrosarcoma expanding into the lungs and things of that sort. If a medical oncologist or pediatric oncologist is seeing someone with a chondroblastoma, performing at least a chest radiograph is not inappropriate if there are concerns about aggressiveness.
