HAVANA — The wife of imprisoned American Alan Gross said Tuesday that she has returned from a trip to Cuba to see her husband and is fearful he will not survive his long incarceration.

Judy Gross said her husband has developed a mass behind his right shoulder blade and suffers from degenerative arthritis and other ailments. The mass is not believed to be cancerous.

The 63-year-old Maryland native, who was obese at the time of his arrest in December 2009, has lost 105 pounds while in custody and appears gaunt in photos released from the Havana military hospital where he is being held.

Gross was on a USAID-funded democracy building program when he was arrested at Havana’s airport. He says he was only trying to provide Internet service to the island’s small Jewish community. He was sentenced to 15 years and has lost his final appeal, leaving him out of legal options.

‘‘I am devastated by his appearance,’’ Judy Gross wrote in the statement following her return to the United States. ‘‘While his spirit remains strong, I fear he is not going to survive this terrible ordeal.’’