Dermatologists: Beware the ‘insulin ball’
This story appears courtesy of MDedge News
EXPERT ANALYSIS FROM SDEF LAS VEGAS DERMATOLOGY SEMINAR
LAS VEGAS – The patient, a 61-year-old man, came to see a dermatologist here about subcutaneous masses on his left arm, abdomen, and on both thighs.
It didn’t take long for Curt Samlaska, MD, of the University of Nevada, Reno, to link the masses to the patient’s daily regimen of seven insulin injections.
But diagnosing the condition required more than asking a few questions. At first, the man appeared to suffer from lipohypertrophy – a lump caused by an accumulation of fat at the site of insulin injections. But, Dr. Samlaska told colleagues, the patient had a different condition that’s barely been discussed in the dermatologic literature – insulin-derived amyloidosis, also known as “insulin ball.”
“It’s probably much more prevalent than we currently appreciate,” said Dr. Samlaska, who spoke in a presentation at the Skin Disease Education Foundation’s annual Las Vegas Dermatology Seminar. “Many cases are not [fully] evaluated and thought to be lipohypertrophy.”
Dr. Samlaska’s patient had suffered from diabetes since age 23 and tightly controls his blood sugar through seven daily injections. He injects short-acting insulin into his arms and abdomen, and long-acting insulin into his thighs.
The masses began appearing about 10 years ago, he told Dr. Samlaska, and he’s suffered more pain while injecting them over time. But the masses are easier to grasp during injections, and the patient’s body did not offer many other sites for injections.
According to Dr. Samlaska, there are about 75 case reports of insulin ball in the medical literature, almost all in endocrinology journals. Ninety percent have a single lump, most commonly in the abdomen, and most have poor glycemic control, he said. (His patient is an outlier.)
Research suggests that insulin balls absorb about 34% of the insulin that’s injected, meaning that patients must inject more than usual to get the same effect. Be careful to advise patients about this, Dr. Samlaska said, because they might try alternative injection sites and get a sudden unexpected flood of insulin – potentially causing hypoglycemia.
He added that another drug – the HIV fusion inhibitor enfuvirtide – also has been linked to amyloidosis.
Pathology can offer insight into whether a mass is an insulin ball or a case of lipohypertrophy, he said. “They’re difficult to distinguish on clinical grounds,” he said, although lipohypertrophy masses are firmer, and they shrink when patients stop injecting insulin. Insulin balls do not.
The treatment for insulin balls is surgical excision, he said. “It’s very easy to do. With the extrusion technique, it comes out like a cheese, like a cyst.”
He said his patient was scheduled to soon undergo excision treatment.
Dr. Samlaska reported no relevant disclosures. SDEF and this news organization are owned by the same parent company.
By Randy Dotinga