Dercum’s disease produces painful fatty lumps beneath the skin, most often on the arms, legs, and trunk. The lumps range widely in size, from as small as a grain of rice to as large as a fist or bigger, and they feel like firm nodules when pressed. Unlike ordinary fat, these deposits hurt, sometimes intensely, and they don’t go away with diet or exercise.
How the Fatty Deposits Look and Feel
The hallmark of Dercum’s disease is subcutaneous lipomas, meaning fatty masses that sit just under the skin. They tend to feel firm and rubbery rather than soft like normal body fat. On imaging, most of these masses measure less than 2 centimeters across their longest side, roughly the size of a pearl or small marble. But some grow much larger, reaching walnut size or beyond. In extreme cases, individual deposits can be as big as a fist.
The skin over a Dercum’s lipoma usually looks normal in color, which is part of what makes the condition easy to miss on a casual visual exam. There’s no rash or redness in most cases. What sets these lumps apart from ordinary lipomas is the pain: they ache constantly or flare with pressure, and the surrounding tissue can feel swollen with a non-pitting edema, meaning the skin doesn’t hold an indentation when you press it. Easy bruising in the affected areas is also common.
Where the Lumps Typically Appear
Dercum’s deposits show up most frequently on the arms, legs, and torso. The inner knees, hips, and upper arms are especially common spots. Some people develop them on the shoulders, back, or chest as well. The pattern depends partly on which clinical type a person has.
In the juxta-articular form, painful folds or nodules cluster near large joints like the knees, hips, or elbows. In the generalized nodular form, visible lipomas are scattered across multiple body regions. The generalized diffuse form is harder to spot because the deposits are very small and spread throughout the body. A person with the diffuse type may not have obvious lumps at all, yet they experience widespread pain in their fatty tissue from head to the soles of the feet. The localized nodular form falls somewhere in between, with painful lipomas concentrated in just a few areas.
Four Clinical Types at a Glance
- Type I, Juxta-articular: Painful fat folds or nodules inside the knees, on the hips, or near the elbows. Sometimes only the upper arms are affected.
- Type II, Generalized diffuse: Widespread pain throughout fatty tissue. Deposits are tiny and sometimes impossible to feel by hand, yet the pain can be severe.
- Type III, Generalized nodular: Multiple lipomas in various body regions, with pain concentrated in and around each lump.
- Type IV, Localized nodular: Painful lipomas confined to a limited number of locations.
Who It Affects
Dercum’s disease overwhelmingly affects women, occurring 5 to 30 times more often in women than in men. Symptoms typically first appear between ages 35 and 50, and most people with the condition are overweight or obese at the time of diagnosis. That said, men with a normal BMI can also develop the disease. Its rarity means many people go years without a correct diagnosis, often being told they simply have ordinary lipomas or weight-related discomfort.
How It Differs From Regular Lipomas and Obesity
Ordinary lipomas are extremely common. About 1 in 1,000 people develop at least one, and they’re almost always painless, soft, and easy to move under the skin. Dercum’s lipomas are firm, often fixed in place, and painful. Pain lasting at least three months in fatty tissue is the cardinal requirement that separates the two conditions.
Distinguishing Dercum’s from simple obesity is also important. In obesity, fat tissue doesn’t typically hurt, and it responds to calorie reduction and physical activity. In Dercum’s disease, the abnormal fat is stubbornly resistant to weight loss. People with the condition often describe losing weight everywhere except in their painful deposits. The non-pitting swelling in the fat layer is another clue that clinicians look for.
A related condition called multiple symmetric lipomatosis also causes abnormal fat growth, but it differs in key ways. It mainly affects the neck, upper back, chest, and upper arms in a symmetrical pattern, usually sparing the lower limbs. It is also rarely painful. Dercum’s disease can show up almost anywhere on the body and pain is its defining feature.
Symptoms Beyond the Lumps
The visible fatty deposits are only part of the picture. A large survey of 110 patients with Dercum’s disease found a long list of accompanying symptoms: fatigue, weakness, sleep disturbances, difficulty concentrating, impaired memory, depression, anxiety, rapid heartbeat, shortness of breath, joint aches, muscle aches, bloating, and constipation. Many of these overlap with other chronic pain conditions, which adds to the diagnostic challenge.
Easy bruising deserves special mention because it’s one of the more visible signs. People with Dercum’s disease often notice bruises appearing with minimal contact, particularly over areas where fatty deposits are concentrated. This can be one of the surface-level clues that something beyond ordinary lipomas is going on.
What Imaging Reveals
When doctors order an ultrasound or MRI, Dercum’s disease shows up as multiple oblong fatty masses sitting in the superficial layer of fat just beneath the skin. Most measure under 2 centimeters in their longest dimension, though larger ones are possible. On MRI, these masses have the signal characteristics of fat but are clearly separated from the surrounding tissue, appearing as distinct oval shapes rather than blending into the normal fat layer. Imaging helps confirm the number and distribution of deposits, especially when physical examination alone doesn’t capture the full picture, as is common in the diffuse form of the disease.