A woman thought she had a bruise from twisting her arm while doing yoga, but it was a rare tumor

• A woman thought she had a bruise on her hand from yoga, but doctors diagnosed her with a tumor.
• She iced her hand and rested it but it didn't get better after two years.

A healthy woman in her thirties who thought she had a bruise on her hand from a yoga injury was diagnosed with a rare tumor, according to a report.

The authors of the report published in JAMA Dermatology said that to their knowledge the woman is the second person to develop what is known as a hemosiderotic fibrolipomatous tumor after an injury— the first case was a man who smashed his hand on a pipe.

The woman initially noticed a painful green-blue mark on the back of her left hand a few days after she twisted it during AcroYoga. She rested it and put ice on it but it was still there after two years, so she got it checked out, doctors from Utah and a Winsconsin-based researcher wrote on February 8.

Doctors found a lesion in the woman's hand, removed it, and sent it to the lab to establish a diagnosis.

She had a rare, slow-growing tumor

They found that she had a HFLT, which is a benign, rare, slow-growing, painful mass that develops in the soft tissues beneath the skin.

HFLTs, which were first described in 2000, can occur on any body part but mostly affect the feet and ankles. It's not yet clear from the literature how many people have had the condition or why people get it.

"The role trauma plays in its development needs further investigation," they said.

The case was published as what is known as a clinicopathological challenge, which clinicians publish to educate others about potentially challenging diagnoses based on an image.

The authors said that clinicians need to let patients with HFLT know that it can recur after it's been removed, but it's very rare for it to transform into a malignant tumor or metastasize.