Diagnostic dilemma: A man huffed computer cleaner for years. Then his hands started growing.

The patient: A 28-year-old man in New England

The symptoms: For two years, the office worker had found it harder to walk and developed an abnormal gait and hip pain.The bones in his hands also became enlarged, and he experienced reduced mobility in his right wrist and forearm.

What happened next: At an initial examination, doctors noted bony masses on each of the patient's finger bones. He was later referred to specialists as the bones of his hands continued to expand. By then, he had developed a stooped posture and also walked with a tilt to the left. The fluoride levels in his blood, urine and bones were all elevated.

The diagnosis: The patient was diagnosed with skeletal fluorosis, a condition caused by long-term exposure to high levels of fluoride.

Exposure to safe levels of fluoride reduces the risk of tooth decay, and fluoride is added to tap water in many countries around the world for this reason. However, when ingested in too-large quantities, fluoride becomes a cumulative toxin that leaches calcium from bones and thus alters their structure. While bone density increases in the early stages of this disease, the bones later start becoming brittle and less elastic.

The man's doctors pinpointed the likely source of his fluoride exposure after some digging. The fluoride levels in the water supply of the man’s town were at "acceptable levels," his doctors noted. But they found a report of an older case that shared similar symptoms; in that instance, the patient had been inhaling canned "dust spray" used to clean computers. The doctors suspected that their patient was also sniffing aerosols and asked the man whether this was true. He admitted that he had been regularly sniffing a computer cleaner for more than three years to get high.

Difluoroethane, the active ingredient in several computer cleaners, is metabolized by the body into a fluorinated compound.

The treatment: The young man stopped abusing aerosols about five months after being examined. After a further six months, his hip function had greatly improved and he could walk almost normally. The man first visited the doctors in 2010, and by 2014, he was walking better and exercising regularly. He stopped attending medical follow-ups by 2015. The doctors concluded that stopping the intake of excess fluoride can gradually alleviate the symptoms of patients with skeletal fluorosis.

What makes the case unique: Skeletal fluorosis is a major issue in certain countries, such as India, where natural fluoride sources can make the fluoride levels in drinking water too high. However, the condition is very rare in the U.S.

This case highlights a potentially unrecognized cause of skeletal fluorosis: cans of compressed air that people use to get high. The authors of the case report believe there may be many more cases similar to this one.