An American imprisoned in Cuba for nearly three years may have terminal cancer, his lawyer and wife said Tuesday.

Cuban doctors who examined the Maryland man, Alan Gross, determined that a growth he has had on his right shoulder for about five months is benign, according to medical records released Tuesday.

But a radiologist in the United States who reviewed the records concluded that the Cuban diagnosis of a temporary swelling was suspect, especially given Gross’s dramatic weight loss. He has lost more than 100 pounds, going from moderately overweight to gaunt.

Gross, 63, has not been evaluated by an independent doctor. His family has copies of Cuban ultrasound and radiology reports from May and June that were evaluated by Bethesda radiologist Alan A. Cohen.

“A soft tissue mass in an adult who has lost considerable weight must be assumed to represent a malignant tumor unless proven to be benign,” Cohen wrote in a letter to Gross’s wife, Judy.

Gross has been behind bars since December 2009, when he was arrested in Cuba for allegedly distributing computer equipment that could be used for Internet access. At the time, he was working under a contract with the U.S. Agency for International Development.

Cuba says Gross was part of a multimillion-dollar U.S. effort to undermine the communist government. He says he was trying to improve communication services for Cuba’s small Jewish community.

Gross initially identified himself as a representative of a Jewish humanitarian organization but later acknowledged he was a U.S. contractor.

He was sentenced to 15 years in prison and has run out of appeals. Although he maintains his innocence, a lawyer, Jared Genser, is appealing to the Cuban government to release him on humanitarian grounds.