Doctors in Argentina have removed a tumor from a woman that was so massive, it looked as if she was pregnant with quintuplets, a lead surgeon said.

The huge growth, tipping the scales at nearly 56 pounds, had been growing inside the 54-year-old patients’ uterus for 18 months. It was taken out during a four hour operation at Gandulfo Hospital near the capitol of Buenos Aires.

Surgeons said they believe the malignant tumor was the biggest ever removed in the world, according to the report.

“I've never seen anything like it in my 34 years of medical service,” lead surgeon Dr. Oscar Lopez said. “Its weight is comparable to that of a 4-year-old boy's.”

The woman, whose identity is not being released, left the hospital weighing 70 pounds less than when she was admitted. She is now back at home recovering.

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