A tumor of cells lining the opening of the sweat glands: At the dermatologist's, John was told that he had poroma, a benign, non-cancerous skin tumor that had developed from the terminal duct portion of a sweat gland.

The presence of cavities in the brain substance: When the postmortem examination was in progress, the doctors found cerebral poromas in the cerebrum that were caused by gas-forming bacteria.

A benign tumor arising from the duct of an eccrine (sweat) gland: An eccrine poroma usually occurs on the palm of the hand (or hands) or the sole of the foot (or feet).