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What was causing the large mass in this young woman’s abdomen?

The patient

This young woman was born and raised in Zimbabwe, coming to the UK in 1999. She had felt some vague abdominal discomfort for a couple of months. Her periods had been regular, her bowels no problem and her general health was fine. She was using the contraceptive device Mirena. Examining her, I was astonished at the sheer size of a soft, mobile mass taking up most of her abdomen. It was as if she had a blown-up balloon inside her, that moved around under her skin. There were no inguinal or supraclavicular glands. I couldn't tell from where it arose and couldn't get below it, but it was almost up to her ribs so I couldn't get above it either.

 First instinct

There were a few differentials on my mind. There was one thing of which I was certain: it wasn't a carcinoma. It was far too soft and mobile.

 Differential diagnoses

• Lipomata

• Ovarian cysts

• Fibroid.

People view lipomata as cutaneous, but they can be  subfascial, subperitoneal, subpleural, even subperiosteal.  I thought a subperitoneal lipoma was a possibility.

Benign ovarian cysts can be divided into functional or non-functional. Functional are the more common, essentially occurring in all pre-menopausal women to some degree. These normally disappear with the next menstrual period. Non-functional include endometriomas, cystadenomas and dermoid cysts. Fertility drugs like clomiphene can lead to huge cysts developing, although there was no record of her receiving any fertility drugs.

Fibroids affect one in five women under 40, and 70% are intramural and can grow to enormous sizes. They are also three times more common in African women, for reasons that are not known. Mirena has been known to shrink fibroids.

 Getting on the right track

Her ultrasound wasn't very helpful: the abdominal organs were obstructed by the large, thin-walled cyst. Next was a CT, which showed an 18x11x19cm unilocular cyst, probably arising from the left ovary. Her uterus had several subserous fibroids.

The gynaecologist remarked that the cyst was a little higher in the abdomen than he would have expected for an ovarian cyst. I knew from examining her that a tumour was out of the question. The patient was then discussed in a multidisciplinary team meeting and her images reviewed. After all this, she had a laparoscopy and a large left-sided ovarian cyst was removed. Histology showed a simple serous cyst. She remains well at three months' follow-up.


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