Dercum’s disease and Lipedema are painful fat conditions that cannot be removed via regular methods such as diet and exercise. People with Dercum’s disease and Lipedema can find it difficult to differentiate which condition they are experiencing. This is due to Dercum’s disease and Lipedema having a similar accumulation of abnormal, painful body fat under the skin. ¹ This article will help distinguish between Dercum’s disease, Lipedema, and other fat-related disorders, including their symptoms and diagnostic differences. 

What are painful fat disorders?

Painful fat disorders are rare conditions that involve painful fat tissue under the skin. Two of the most common painful fat disorders are Dercum’s disease and Lipedema, which are classified as rare adipose disorders (RADs).² RADs are distinguished by the presence of exercise and diet-resistant fat. The symptoms and pain stem from the malfunctioning of the lymphatic and vascular system, causing increased tissue fluid and pressure. RADs are usually underdiagnosed and can be mistakenly classified as obesity.²

Dercum’s disease (Adiposis dolorosa)

Dercum’s disease, also called Adiposis Dolorosa, is defined by the presence of several painful fatty growths (lipomas).³ Dercum’s disease most commonly affects people assigned female at birth (AFAB), from around 35 years of age.⁴ Lipomas are found beneath the skin, commonly in the upper body, upper arms, and upper legs. They can also form at the feet, neck, hands, and head, although these areas are less common. Lipoma size can vary from a pea to a grape to fist size.³

What are the causes?

The cause of Dercum’s disease is mostly thought to be sporadic (random), with some cases of genetic causes. ¹ Although the exact cause is unclear, possible factors include: 

1. Inflammation - inflammation may trigger the release of ‘pain-causing’ chemicals in the body⁵
2. Trauma - symptoms have appeared after injuries in some cases
3. Problems with the lymphatic system (the system that drains extra fluid from the body) - if lymph vessels don’t drain fluid correctly, it can form a buildup, leading to lipoma formation 
4. Hormone effects - high levels of glucocorticoids (a steroid hormone regulating metabolism) can affect fat metabolism⁵ 

What are the signs and symptoms?

• Painful lipomas (fatty lumps) - the main feature 
• Chronic pain (over 3 months) 
• Overweight/ obesity⁵

Pain 

Pain may be described as ‘burning’, and can be severe and long-lasting (over 3 months). In advanced cases, pain may even be disabling. However, pain may not be immediately noticeable and may only be recognised after some time. ⁵

Appearance 

Lipomas may be small and scattered across the body (generalised form), or may appear larger and more noticeable under the skin (nodular form). The skin can keep a normal appearance, with no colour change, but the lumps will be visibly defined and soft. ⁵

Fatigue or weakness 

Associated symptoms of Dercum’s disease may manifest as 

• Sleep disturbances 
• Unstable emotions 
• Depression/ anxiety⁵

People may also experience impairment in cognition, dementia, and epilepsy, but less commonly.

Common sites 

Lipomas can usually be found in:

• Legs
• Arms
• Torso (in both the front and back)
• Buttocks (around 70% of cases)
• Face (around 20% of cases)
• Neck (around 33% of cases)
• Under the ribs
• Inner upper arms
• Inner thigh
• Outer thigh⁵

Less common symptoms 

• Joint or muscle pain
• Constipation 
• Fast heart rate (tachycardia)
• Shortness of breath
• Diabetes ⁵

However, these symptoms may not be directly linked to Dercum’s disease and could be related to obesity. 

Types of dercum’s disease

• Type Ι (juxta-articular) - at early stages of the condition, painful folds of fat develop around the joints ²
• Type II (generalised type) - a more advanced stage than Type I, where pain is more widespread in the body 
• Type III (nodular type) - intense pain around fatty lipomas, and possible presence of angiolipomas (lipomas with blood vessels) ²

Conditions often confused with dercum’s disease

• Familial Multiple Lipomatosis - inherited multiple lipomas, which are usually painless
• Angiolipoma - painful lipomas³

Lipedema

Lipedema is commonly misdiagnosed as obesity and is more commonly found in people assigned female at birth (AFAB). The condition can be triggered or worsened during puberty, pregnancy, and menopause. Although Lipedema is an underdiagnosed condition, it is thought to affect millions of people AFAB. ¹

The fat distribution in Lipedema can be distinguished by its ‘gynoid pattern’ (distribution around the hips, thighs, and buttocks). This can give a ‘pear-shaped’ appearance. Another prominently affected area is the arms, which 80% of people  AFAB experience, while the torso is usually not affected in the early stages. ¹

What are the causes?

Lipedema is classified as an autosomal dominant inherited condition, suggesting a genetic cause. However, neither Lipedema or Dercum’s disease has a known gene or biomarker responsible. ¹

The pain and swollen feeling of Lipedema is due to the fat tissue behaving as if it is ‘under attack’, activating its immune system. This activation results in complement proteins (immune proteins) and macrophages (immune cells) being hyperactive in the fat. This hyperactivity can cause: ¹

• Inflammation - resulting in swelling and pain 
• Increased leaking of fluid from the lymph vessels into the tissue 
• Hardening of fat tissue over time ¹

What are the signs and symptoms?

• Painful fat tissue - the main symptom 
• Sore, small lumps/bumps (nodules) - resembling styrofoam balls 
• Hard/heavy fat
• Lymphatic problems - oedema (swelling), secondary lymphedema (lipolymphedema) in the feet and hands, and skin too swollen at fingers/toes to be pinched ¹

Stages of lipedema 

Lipedema progresses in 4 stages

• Stage 1: Skin is smooth, fat is enlarged, but no abnormal appearance 
• Stage 2: Formation of lumps and nodules (usually in the hips, thighs, knees, and arms)
• Stage 3: Uneven growth of fat into large folds, which may press against tissue below, worsening circulation and swelling
• Stage 4: Lipolymphedema - fluid swelling (lymphedema) forms on top of Lipedema, worsening swelling¹

Types of lipedema

There are 5 different types of Lipedema:

• Type 1 - affecting mainly the hips and buttocks area
• Type 2 - affecting the hips, buttocks, and thighs down to the knee region
• Type 3 - affecting the hips, buttocks, and thigh areas down to the ankle, where there may be a ring-like band of fat
• Type 4 - affecting the arms, where there may be a ring-like band of fat at the wrist 
• Type 5 - affecting mainly the lower region of the leg¹

Conditions often confused with lipedema

• Familial Multiple Lipomatosis - inherited multiple lipomas, which are usually painless
• Obesity - excess weight without resistance to diet and exercise, with no pain directly in the fat tissue  
• Lymphedema - a separate condition involving swelling 
• Lipolymphedema - stage 4 of Lipedema, where lymphedema develops¹

Other painful fat disorders

Although Dercum’s disease and Lipedema are the most commonly known painful fat disorders, there are many other conditions which have overlapping symptoms. Some of these conditions are Familial Multiple Lipomatosis (FML), Lymphedema, and Madelung’s disease (also known as Multiple Symmetric Lipomatosis).²

Familial multiple lipomatosis

FML is a genetic condition where multiple lipomas form, usually passed through families. It affects both people assigned male at birth and people assigned female at birth. There is usually no pain behind the lipomas unless they enlarge, which is what distinguishes them from Dercum’s disease. Dercum’s disease is considered to be a painful variant of FML.²

Lymphedema 

Lymphedema occurs upon the dysfunction of the lymphatic draining system, resulting in the buildup of fluid and leading to a buildup of fat. Lipedema can advance to Lipolymphedema (stage 4 Lipedema), where swelling occurs in the hands and feet. Muscle tissue may also be affected with Lymphedema, unlike Lipedema.²

Madelung’s disease (Multiple symmetric lipomatosis) 

Madelung’s Disease is a rare condition that entails painless, symmetric fatty lumps. The condition's painlessness is a defining feature of both Dercum’s disease and Lipedema. There are 3 types of Madelung’s disease, affecting the neck and back, the shoulders and chest, and the thigh area, respectively. The cause of the condition is not fully understood, but alcohol is thought to be a trigger.²

Differential diagnosis: comparing conditions

Summary 

Dercum’s disease and Lipedema are painful, rare fat conditions which are exercise and diet-resistant, often misdiagnosed as obesity. People experiencing Dercum’s disease may have painful lipomas, usually affecting the upper body, with associated health problems of diabetes and cognitive symptoms. Lipedema usually develops during hormonal changes, mainly affecting the lower body, with signs of easy bruising and hypermobility. Diagnosis is made through examinations, assessing patient history, and ruling out other conditions. Treatment focuses on pain and symptom relief, as the causes of the conditions are unknown. Other rare fat disorders have overlapping features, so careful differential diagnosis is important.