Doctors in Germany said they had removed a tumour weighing 28kg - big enough to fill a wheelbarrow - from a 60-year-old woman who had previously been diagnosed as obese.
A spokesman from the university clinic in the eastern city of Dresden said the woman, Irmtraud Eichler, had made a full recovery after the seven-hour operation and was now able to walk again with crutches.
The so-called "borderline" tumour, measuring 60cm by 50cm, attached itself to an ovary and Eichler began to put on weight at an alarming rate.
Her doctor put the weight gain down to a combination of diabetes and a lack of activity, and prescribed a course of anti-obesity medicine. However, when she could barely stand because of the swelling, her daughter insisted on a second opinion and an ultrasound scan revealed the growing tumour, which was found to be neither benign nor especially malignant.
The operation removed not only the tumour but also her uterus, ovaries and thyroid, which had expanded, causing her windpipe to contract and lead to breathing difficulties.
When removed the tumour filled a wheelbarrow, the spokesman said. Eichler lost a total of 40kg during the operation and described herself as "super happy".
"I cannot thank the doctors enough. I am a new person," she said.