Spinal tumors are rare. And if you have one of these strange masses along the spine, the diagnosis could take several weeks. Be prepared for your physician to rule out many other conditions first.

“One symptom is back pain, which everyone has had. Spinal tumor is not the first thing you think of,” says James Schuster, MD, PhD, Associate Professor of Neurosurgery at Penn Medicine. “The physician might have investigated other potential causes first. So, a diagnosis can seem somewhat delayed.”

“Spinal cord tumors usually grow slowly,” adds Neil Malhotra, MD, Assistant Professor of Neurosurgery at Penn Medicine. “Many patients will have mixed sets of symptoms.” This can lengthen the diagnosis process as well.

That said, thanks to sophisticated imaging options, spinal tumors are still diagnosed more quickly than they used to be. Here’s a look at the why’s, where’s, and how’s of spinal tumors.

What causes a spinal tumor to form

The short answer: In most cases, physicians and researchers don’t know. Anyone can develop a spinal tumor, but they remain extremely uncommon.

While there are a number of potential causes of spinal tumors, by far most people who develop them have a history of other cancers. Dr. Malhotra explains that this is extra important for patients who are undergoing cancer treatment or who are in remission. If they begin experiencing strange symptoms, they should be more rigorously screened for spinal tumors than patients without a cancer history.

Central nervous system tumors (those in the brain or spinal cord) affect 359,000 people in the US, according to the National Institute of Neurological Disorders and Stroke. Between 85 and 90% of those occur in the brain, says the American Association of Neurological Surgeons (AANS).

That means the other 10 to 15% of cases—affecting 35,900 to 53,850 people—involve spinal tumors. Those masses are found in the vertebrae, spinal cord, spinal nerve roots, or dura matter—the outer membrane surrounding the spinal cord.

For comparison, an estimated 246,000 women in the US will be diagnosed with breast cancer, and about 180,000 men will be diagnosed with prostate cancer in 2016, according to the National Cancer Institute.

So, spinal tumors are not nearly as common as breast or prostate cancer. But that doesn’t mean they’re unheard of. Every year, some 10,000 Americans develop metastatic spinal cord tumors—the kind of tumor that will spread or that is caused by spreading cancer.

Spinal tumor symptoms

You can have a variety of symptoms, depending on the tumor’s size and location, according to the AANS:

• Abnormal gait
• Loss of sense of position in space
• Numbness
• Weakness
• Tingling
• Difficulty walking in the dark
• General mid-back pain
• Pain at night
• Loss of bowel or bladder function
• Paralysis to varying degrees
• Scoliosis (curvature of the spine)

Don’t jump to any conclusions based on your symptoms, though. Back pain, in particular, can have multiple causes.

“While back pain is common, spinal tumors, fortunately, are uncommon,” says Dr. Schuster. “Over time, a back strain will get better. We’re looking for recurrent, persistent, worsening symptoms—the pattern of the pain.”

Dr. Schuster adds that at Penn Medicine, spinal tumors might seem more common than they are in the general population because doctors from throughout the region refer complicated cases to the specialists there.

Making a difficult diagnosis

Most often, a person will visit her primary care physician complaining of back pain and possibly a handful of other symptoms.

After examining the patient and evaluating her symptoms, the physician might encourage her to wait to see if her symptoms improve over time. The physician might prescribe conservative treatments as well, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or physical therapy.

If symptoms don’t improve, the physician might then order an imaging test, such as an MRI, to get a better look at what’s happening. The MRI will show whether a tumor is growing in or near the spinal column, or if another culprit is causing the pain—such as arthritis.

“The diagnosis is accelerated today,” Dr. Schuster says. “You can get an MRI and see a neurosurgeon the next day.” In the past, the diagnosis might have involved an X-ray, physical therapy, maybe a trip to the ER, and then, finally, an MRI scan.