Many share her experience, said Ronica Mukerjee, a nurse practitioner who does medical outreach in Queens with transgender women. “Silicone isn’t always deadly, but injecting free loose silicone is very dangerous in large quantities,” Ms. Mukerjee said. “Silicone drifts. I’ve seen silicone injected in their hips end up in their ankles.”

In 2002, Ms. Quispe’s primary-care doctor referred her to a plastic surgeon at Beth Israel Medical Center who, she said, told her the last injections she received had been industrial oil rather than silicone. Trying to remove it surgically could be life-threatening because the oil was embedded in the muscle tissue and the entire muscle would have to be excised from her buttocks and hips. Removing the tissue would leave her with massive cavities, altering her body weight and metabolism drastically, and increase her suffering.

He advised her, she said, to take medication for the pain instead of risking surgery. Since then, she has visited several other plastic surgeons with the hope that one might have a different answer — but none have. Five of her friends were injected by the same pumper, she said, and are experiencing similar problems.

Now, Ms. Quispe spends most of her time in her tiny apartment in Vinegar Hill, Brooklyn, in the Farragut Houses. Ms. Quispe’s home is decorated with miniature Buddhist statues and several plastic Chinese tapestries tacked on the wall for good luck. The front door opens to a small kitchen with a narrow table and two chairs squeezed next to an old refrigerator. A short corridor leads to her bedroom, most of which is dwarfed by a queen-size bed, where she spends most of her time safely removed from the jeering comments of strangers.

“I’d rather be inside my place because everyone looks at me like I’m an alien,” she said, wincing and shifting uncomfortably on the chair. “I’m a human being just like everyone else.”

STORIES like Ms. Quispe’s wouldn’t be possible without women like S., a pumper who agreed to be interviewed only on the condition that she be identified by her first initial because what she does is illegal. Born male, S. said, she ran away from home at 15. She met an older transgender woman at a nightclub who helped her begin her transition. The same woman also introduced her to prostitution, and S. used that money to pay for female hormones when she was 15 and for silicone injections that she began receiving at 24, in 1985, from Dr. David R. Wesser, a New York surgeon then well known in the transgender world.