A Revere man was held on $15,000 cash bail today as prosecutors detailed the injuries he allegedly inflicted upon his girlfriend’s 5-year-old son last week, Suffolk County District Attorney Daniel F. Conley said.

JOSEPH TESTA (D.O.B. 5/19/82) was formally charged today with assault and battery on a child causing serious bodily injury, wantonly or recklessly permitting serious bodily injury to a child, and child endangerment. Assistant District Attorney David Deakin recommended that he be held on $250,000 bail.

Deakin, the chief of Conley’s Family Protection and Sexual Assault Bureau, told Chelsea District Court Judge Benjamin Barnes that emergency medical personnel responded to the area across Revere Beach Parkway from the boy’s home midmorning on Friday to find the child in “serious distress.”

The child was suffering from massive intracranial bleeding, Deakin said, and had a “golfball-sized” lump on his forehead. In addition, the boy had bruises in various states of healing to a number of body parts, including his occipital bone, the inside of his ear, his hip, and his knees.

The boy was rushed by ambulance to Massachusetts General Hospital, where he underwent emergency surgery Friday. He remains hospitalized in stable condition.

Deakin said the boy’s mother asked Testa to stay with the boy at her Revere home while she ran errands on Thursday afternoon. At that point, Deakin said, the boy seemed fine. When she returned about two hours later, however, he seemed “different” and lethargic, according to her statements to investigators. He went to bed uncharacteristically early.

The next morning, Deakin told the court, the boy vomited shortly before his mother left for work. About an hour later, she received a call from Testa in which he allegedly said he had taken the boy out to get some air and that he was unconscious. She instructed him to call 911, prompting the medical response that led to his hospitalization.

Testa was represented today by attorney Shannon MacAuliffe. He will return to court on May 23.