Clinical aspects of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is often a chronic skin disease of unknown etiology characterized by formation of non-infectious inflammatory nodules, abscesses, and suppurating skin tunnels mainly in axillae and groins. The lesions are painful, scarring, malodorous and cause suffering, and social stigmatization. In this thesis different clinical aspects of HS are studied: continuous development of a clinical scoring system, bacterial colonization, relation to social factors and comorbidities, including mental health.

In study I, the objective is to evaluate the modified Hidradenitis Suppurativa Score (HSS) and to describe the interobserver reliability of the HSS and also to document its correlation with risk factors and disease severity. A total of sixty-one patients were scored in various combinations according to the HSS protocol: Patients' reports of weight and height, smoking habits etc., were registered, and Dermatology Life Quality Index (DLQI) questionnaires. The results suggest that HSS is simple to use and shows low interobserver variability, and it correlates with selected risk factors, indicating that it reflects a valid estimation of disease severity.

In study II, bacteria isolated from HS lesions during exacerbations of the disease were studied. Patients with HS with acute nodules or abscesses were examined during carbon dioxide laser vaporisation. Bacterial samples were taken from the skin surface (before surgery) and then from the deeper layers (during surgery). Coagulase-negative staphylococci (CNS) were the most common bacteria, but contrary to what we expected, Staphylococcus aureus was not found in any cultures from acute inflammatory lesions of HS exacerbations.

In study III, a registry-based cross-sectional study of social characteristics and comorbidity in all HS patients in Sweden as well as the prevalence of lifestyle factors in Swedish pregnant women with HS was performed. A total of 13,538 HS patients diagnosed with HS in specialized care and a subgroup of 1,368 HS patients who had undergone pregnancy were defined, described, and compared with data from the normal population. The HS patients were more often women, unmarried, and had lower education as well as lower income. The pregnant women with HS showed higher prevalence of overweight, obesity, and smoking.

In study IV, the same population of 13,538 HS patients in Sweden as in study III was used in a registry-based cross-sectional study aiming at investigating the relation between mental health and the disease. The result compared with data from the normal Swedish population, indicates that HS patients suffer more frequently from psychiatric diseases, including depression, anxiety, mood disorders, autism, and ADHD. The findings are reflected by the fact that psychotropic drugs are more often prescribed to HS patients. Dermatologists should be aware of the important association between HS and psychiatric disorders.

List of scientific papers

I. Sartorius K, Killasli H, Heilborn J, Jemec GBE, Lapins J, Emtestam L. Interobserver variability of clinical scores in hidradenitis suppurativa is low. Br J Dermatol. 2010; 162: 1261-1268.
https://doi.org/10.1111/j.1365-2133.2010.09715.x

II. Sartorius K, Killasli H, Oprica C, Sullivan Å, Lapins J. Bacteriology of hidradenitis suppurativa exacerbations and deep tissue cultures obtained during carbon dioxide laser treatment. Br J Dermatol. 2012; 166: 879-883.
https://doi.org/10.1111/j.1365-2133.2011.10747.x

III. Killasli H, Sartoris K, Emtestam L, Svensson Å. Hidradenitis suppurativa in Sweden: a registry-based cross-sectional study of 13,538 patients. Dermatology. 2020; 236: 281-288.
https://doi.org/10.1159/000505545

IV. Killasli H, Lönndahl L, Sartorius K, Lapins J, Sjöstrom K, Svensson Å, Emtestam L. Mental health in Swedish patients with hidradenitis suppurativa. [Manuscript]