The Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL, receives several inquiries related to bone biopsies. Randi Gold, VMD, PhD, DACVP, an anatomic pathologist for TVMDL, provides thorough explanations for six questions related to bone biopsies.
Properly performed, bone biopsies offer valuable insights. The following questions will help broaden your understanding of this diagnostic tool:
- How should you prepare before a bone biopsy?
- When and why should lymph nodes be removed before amputation?
- Should an amputated leg be sent as fixed or fresh?
- What are the key principles for tissue handling?
- How should cancers like osteosarcoma be approached?
- What should be included in a clinical history report for histologic interpretation?
How should you prepare before a bone biopsy?
Before performing a bone biopsy, carefully plan the target site and select the appropriate instruments.
Proper equipment
Before the collection process, it is essential to have the proper equipment for a bone biopsy. The wrong tools can cause inadequacy. Gold recommends using a Jamshidi needle.
“Especially for core samples, the larger the needle, the better,” Gold said.
Target the medulla cavity
Inadequate samples are a common problem that pathologists encounter when reviewing bone biopsy submissions.
“Oftentimes, clients mistakenly send samples collected off the periosteal surface of the bone,” Gold said. “Most of the time, these are not testable or representative samples of the true lesion.”
Instead, clients should focus on penetrating the cortex and collecting the samples deep within the bone by targeting the medulla cavity.
“That’s where the tumor cells are going to be, or the areas of active infection for an osteomyelitis,” she said.
In addition, to taking samples from the center of the mass, the veterinarian should take samples from multiple areas. This approach maximizes the likelihood of obtaining a representative and diagnostic tissue.
“The center of a tumor might have a lot of necrotic tissue if it’s been there long enough, so even if you’re in the right spot, you might not get viable tissue or a good answer,” Gold said. “In addition, if that sample is damaged from heat artifact, which is a common problem, multiple samples will increase the chances of getting at least one viable sample.”
She recommends including samples from transition areas where normal and abnormal tissue meet.
Tip: Use radiographs to help determine the correct needle depth and placement.
“Radiographs give you an idea of what size to look for,” Gold said. “Veterinarians can do this by enlarging the image to the actual size of the animal using the marker, hold the needle up against the film, and see how far you actually have to go to get it into the center of the area of interest.”
This technique allows for precise placement while minimizing the risk of overshooting, undershooting, or misalignment.
Tip: Capture post-biopsy radiographs.
A post-biopsy radiograph will confirm the needle reached bone and retrieved a core sample, and not just soft tissue.
When and why should lymph nodes be removed before amputation?
When: Before the surgical disruption.
In cases where limb amputation is planned, removing the draining lymph nodes pre-surgery is the best practice. The lymph node should be isolated and sent to the laboratory in an individual formalin container.
Why: To prevent lost lymph nodes and miss a metastasis diagnosis.
If the draining lymph nodes are lost during or after limb amputation, a key opportunity for accurate staging is gone. Without them, it becomes much harder to determine the degree of metastatic spread if present.
“It’s much easier if the lymph node can be removed ahead of time because once everything’s already dissected post-surgery it makes it much harder to find,” Gold said. “This is especially challenging when dealing with small animals like cats because their lymph nodes are tiny to begin with. The pathologist might also spend a lot of wasted time looking for the node when it’s still with the patient and not in the part of the leg submitted.”
Should an amputated leg be sent as fixed or fresh?
TVMDL accepts both fresh and fixed limbs. There are pros and cons for both options.
Submitting fixed tissue
Pros:
- Immediate fixation means faster tissue processing and report turnaround.
- Stabilizes tissue for transport, decreasing the likelihood of decomposition if shipment is delayed.
Cons:
- Alters color and texture so subtle lesions may be harder to see during gross dissection.
- Makes it harder to manipulate the tissues during the dissection to access the lesion
- Cannot collect samples for bacterial or fungal culture if needed.
- Large limbs may not fit standard formalin containers.
Tip: Do not wrap a fixed limb in tape or vet wrap because formalin penetration will be blocked.
Submitting fresh tissue
Pros:
- Better gross evaluation of lesions before fixation.
- Easier to cut, manipulate, and examine.
- Allows collection of samples for bacterial and fungal culture.
Cons:
- Fixation is delayed, which may slightly increase turnaround time.
- Requires careful cooling and transport to maintain tissue quality.
What are the key principles for tissue handling?
Immediately place the samples in formalin post biopsy
Delays between biopsy and fixation can result in tissue dryness, poor quality, and possibly untestable condition.
“You don’t want it to sit around exposed to air, so it’s important to get it into that storage container immediately,” Gold said. “But use care when transferring the biopsy from the tip of that needle into formalin.”
Tip: Never use forceps when handling tissue.
Using forceps may compress and distort the tissue structure.
“Never grab tissue with a forceps to pull them out of the jamshidi or needle that you are using because it can cause crush artifacts unknowingly while you’re transferring it,” Gold said. “If you are using a Jamshidi make sure once you collect the sample you don’t push it out the tip as that will crush the core. The specimen should be extruded in a retrograde fashion using the biopsy probe.”
Use a balance of force and delicacy during collection
While it takes force to obtain bone biopsy samples, excessive pressure or rough handling can damage the tissue, leading to distortions that compromise the diagnostic quality.
“You use this balance to avoid crush or heat artifact that can compromise the microscopic characteristics,” Gold said.
It is important to exercise extra caution during the rotational movement of the needle. Performing twisting motions too forcefully or quickly generates excessive heat. In many cases, this heat may even damage or melt the sample.
How should cancers like osteosarcoma be approached?
Osteosarcoma is commonly encountered and aggressive
Differentiating osteosarcoma from other tumors is essential for determining prognosis and treatment because it has high potential for local invasion and metastasis.
“Because there are different types of osteosarcoma, veterinarians should target relevant areas,” Gold said. “Sometimes they can be found on the surface but most of them will start off within the medullary cavity.”
What should be included in a clinical history report for histologic interpretation?
Clients should send a thorough report including a:
- Signalment
- Brief clinical background
- Radiographic findings
- Current/previous treatment
- Additional other relevant history
An emphasis on imaging
In addition to the written radiographic report, the x-ray imaging is also very useful.
“Us pathologists are often very visual, so we like to actually see things versus reading a lengthy report,” Gold said. “I personally like to visually see where the lesion was.”
Email all images and reports relevant to submissions to clientservices@tvmdl.tamu.edu.
Final considerations
Bone biopsies are a critical diagnostic tool in veterinary medicine, providing essential information for differentiating cancerous tumors and guiding appropriate treatment plans. While the procedure carries inherent risks, careful technique and proper sample handling help minimize damage and promote high quality diagnostic results.
Clear communication with TVMDL further enhances the value of this procedure and supports better patient outcomes.
For more information about bone biopsies and other diagnostic services offered by TVMDL, visit tvmdl.tamu.edu or call (888)-646-5623.
