Nodule showing up on MRI

My husband had a lumbar MRI at the beginning of December. His symptoms became much worse and more widespread than he initially relayed to the neurologist. He is now awaiting a full spinal and brain MRI, but this is the comments from his lumbar MRI - ‘right L5-S1 moderate lateral recess stenosis due to disc bulge and a 4mm nodule in the spinal canal at L2 level. In order to characterise further this nodule and rule out other lesions…’
What is a nodule? Does anyone have experience of this showing up on their MRI or know what the term ‘nodule’ is used to describe? The neurologist said on the phone he couldn’t tell what is was.

I notice no one has replied to you. It guess it will be because we have not come across this, so can’t help. I hope your husband doesn’t have to wait too long for the MRIs and that the neurologist will then be able to determine what is going on, and you both wil get answers.