Dercum's disease (DD) is characterised by pronounced pain in the adipose tissue and a number of associated symptoms. The pain is chronic (for more than 3 months), symmetrical, often disabling  and resistant to analgesics . The pathogenesis of DD is unknown, but inflammatory components have been proposed [2–4]. However, laboratory markers for inflammation, such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), are usually normal in the condition [4–17]. However, a few studies have revealed that some of the patients have elevated levels of CRP and ESR. A study from 1937 of 112 women with DD, reported that 66% had an ESR > 15 mm . Moreover, in a study by Herbst and Asare-Bediako , 33.4% of the patients with DD had elevated CRP levels and 37.5% elevated ESR levels. However, 38.2% of the patients included in the study had autoimmune disease, such as rheumatoid arthritis and lupus. In the same study 31.2% of the patients had positive titres for antinuclear antibodies (ANA). It is unclear if these patients were among the 38.2% that had an autoimmune disease. Case reports have shown that markers for autoimmune disease, such as rheumatoid factor (RF), antinuclear antibodies (ANA), anticardiolipin antibodies (ACA), perinuclear anti-neutrophil cytoplasmic antibodies (pANCA), cytoplasmic anti-neutrophil cytoplasmic antibodies (cANCA) and antibodies against native DNA, are commonly negative in DD [4, 6, 11, 15]. Regarding blood cytokines, a small study including 10 subjects and 5 controls  indicated that macrophage inflammatory protein (MIP)-1β might be lower in patients with DD than in normal controls. Moreover, a trend towards higher levels of interleukin (IL)-13 and levels of fractalkine were detected.
In previous reports and studies, an inconsistent picture of the histological appearance of the adipose tissue in DD has been described. Fat biopsies in different case reports have revealed histologically normal adipose tissue without inflammation [8, 10]. However, pathological findings have been described in other studies. Dercum originally considered the most interesting histological finding to be interstitial inflammation of the nerves in the adipose tissue of the painful sites [1, 20], which has only been confirmed in one case report .
As regards inflammatory signs in the adipose tissue in DD, leukocytes and plasma cells have been detected in two cases [3, 22]. In addition, Herbst et al.  found multi-nucleated giant (MNG) cells in three of the DD patients (n = 5) and in none of the controls (n = 5). Multi-nucleated giant cells are produced by activated, pro-inflammatory macrophages. However, no differences in number of macrophages could be seen between the patients and the controls.
Other pathological findings in fat biopsies described in DD are increased levels of connective tissue [19, 23], fibrolipoma with numerous embryonic vessels, , reactive infiltration of fibrotic elements and small angiomas , granulomas  and capillary microthrombi .
The aim of this investigation was to examine the histological appearance of the adipose tissue in patients with DD, with particular regard to inflammatory signs in a larger series of patients, and compare them with healthy, obese, body mass index (BMI)-matched controls and controls with normal BMI.