As a physician writer, I'm very hesitant to speculate about the medical problems of public figures. Famous or infamous, they deserve their privacy, and besides, medicine is so complicated that making diagnoses based on scattered press reports is akin to divination by tossing chicken bones.

But then along came Tom Petters' lawyers' plea for leniency on the basis that their client — who is facing sentencing after being convicted of 20 counts of fraud, money laundering and conspiracy — is suffering from a pituitary-gland tumor. A Star Tribune article yesterday quoted court documents submitted by Petters' defense attorneys:

"The long-term prognosis for Mr. Petters' condition is bleak; he faces the risk of blindness. The tumor is not growing at the moment but cannot be ignored."

A review of this quote among a handful of my colleagues who diagnose and treat pituitary gland tumors — neurosurgeons, neurologists, endocrinologists — elicited a common clinical impression: laughter with hints of deviancy. That's like saying because he's alive, one day he's going to die, quipped a neurologist.

It's not that pituitary-gland tumors are something to laugh at. The gland sits deep in the brain and releases hormones that help control lactation, thyroid function, and sex hormones. Because of the gland's proximity to the optic nerves (the nerves that give us vision), a pituitary tumor can indeed lead to blindness if it grows large enough to cause compression. A tumor that is hyperfunctioning and putting out too much hormone can cause serious medical problems.

But MRI scans and autopsy studies show that up to 10 percent of the population have small pituitary adenomas (a benign, nonmalignant growth). Most of those are small, less than 1 centimeter, and most cause no symptoms — which is why they are commonly referred to as "incidentalomas."

If a tumor isn't secreting excess hormone, the patient can be simply observed. And even if the tumor is growing, it can be periodically monitored by MRI and appropriate therapy rendered when and if needed.

From the statement given by his defense attorneys, Petters appears to have an incidentaloma: a stable tumor that isn't growing and doesn't require medical therapy or surgery.

So is his appeal for leniency on that basis just another fraud? From this distance it sure looks like the latter, but U.S. District Judge Richard Kyle will be the one to pass judgment on that. One thing can be said for certain: Petters' brain carries pathological features.