Is There an Association Between Hidradenitis Suppurativa and Fibromyalgia?

To the Editor:

Hidradenitis suppurativa (HS) is a chronic inflammatory condition that affects approximately 1% to 4% of the worldwide population and is 3 times more common in females than in males.¹ The condition is characterized by painful inflamed nodules in apocrine gland–bearing regions that can progress to abscesses, sinus tracts, and/or scarring. Hidradenitis suppurativa is associated with intense pain, work disability, and poor quality of life.¹

Recent evidence has suggested that HS is an autoimmune disease resulting from dysregulation of the γ-secretase/Notch pathway, leading to stimulation of the toll-like receptor–mediated innate immunity that contributes to occlusion and inflammation of the hair follicle. Additionally, elevated levels of proinflammatory cytokines such as tumor necrosis factor α and IL-17 are seen in HS lesions.² The autoimmune nature of HS may account for its increased association with other autoimmune disorders such as thyroid disease and potentially with other unexplored conditions such as fibromyalgia.³

Fibromyalgia is a chronic pain condition that primarily affects females and is commonly associated with other autoimmune conditions.⁴ The primary objective of this retrospective study was to determine the prevalence of fibromyalgia in HS patients and assess if there is an association between HS disease severity and development of fibromyalgia.

We conducted a retrospective chart review of patients at Wake Forest Baptist Medical Center (Winston-Salem, North Carolina) who were 18 years and older and had a diagnosis of both HS and fibromyalgia from January 2008 to November 2018. The primary end point was the prevalence of fibromyalgia in the HS population. The secondary end point was the association of HS disease severity with the development of fibromyalgia. Hidradenitis disease severity was defined according to the number of body areas affected by HS: mild disease involved 1 body area, moderate disease involved 2 body areas, and severe disease involved 3 or more body areas. Patient age, sex, and race also were recorded.

A total of 1356 patients were seen during this time period for HS. The prevalence of fibromyalgia in the HS population was 3.2% (n=44). Ninety-five percent (42/44) of patients with HS and fibromyalgia were women; 22 (50%) patients had severe disease, 12 (27%) had moderate disease, 7 (16%) had mild disease, and 3 (7%) had an unknown number of affected body areas. Fifty-seven percent (25/44) of patients were diagnosed with HS prior to the diagnosis of fibromyalgia (Table).

In our study, the prevalence of fibromyalgia in HS patients was lower than the overall prevalence estimates of up to 6% in the United States.⁵ Although fibromyalgia is associated with other autoimmune conditions, it does not appear that fibromyalgia occurs more frequently in the HS population than the general population. A limitation of this study was that we only included academic outpatient clinic visits at one institution, which may not be representative of the entire HS population. Fibromyalgia was one of the many pain disorders in this population of patients. In this population of HS patients, many had pain issues with diagnoses ranging from chronic pain syndrome to osteoarthritis. Additionally, many patients could meet criteria for fibromyalgia but may not have been formally diagnosed, as it is a diagnosis of exclusion and there is no formal test for diagnosis. Further studies are recommended to evaluate the association between HS and fibromyalgia.