Evaluating the Use of Hematological Parameters in Staging Hidradenitis Suppurativa

Introduction. Recently, it has been shown that hematological parameters may be used as markers of inflammatory response. In this study, the authors aimed to identify the potential roles of the neutrophil-lymphocyte ratio (NLR) and other hematological markers in the evaluation of hidradenitis suppurativa (HS), a chronic, recurrent inflammatory disease. Materials and Methods. A total of 35 patients, diagnosed with HS between January 1, 2012 and December 31, 2014, were categorized into 3 groups according to the Hurley staging system. The basic patient demographics, the anatomic regions involved, and the hematological parameters including NLRs were evaluated in the present retrospective chart review. Results. Hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin levels were greater in stage I than stage III, while hematocrit, red cell distribution width (RDW), mean platelet volume, mean corpuscular hemoglobin concentration levels, and platelet counts did not differ between the stages. White blood cell and neutrophil counts were higher in stage III than stage II, while lymphocyte counts were lower in stage III than stage II. The NLR of stage I was detected as being significantly higher than stage II and lower than stage III. Conclusion. The present study shows hematological markers, and NLR in particular may be related to the severity of HS. Further studies are required to demonstrate the significance of NLR in the evaluation of HS.

Hidradenitis suppurativa (HS) is a chronic, recurrent, inflammatory disease characterized by boils, sinus tracts, fistulae, and scarring formation. It is accepted that follicular occlusion is central to its pathogenesis.¹ The apocrine glands are spared during the initial phase, but inflammation of apocrine glands may occur as a secondary process following dilatation and rupture of pilosabesous unit.^2-4 

The exact etiology of HS remains unknown, but the effective use of anti-inflammatory drugs and the absence of pathogenic bacteria suggest a critical role for the immune system in the pathogenesis.¹

Recent studies^5-8 have shown the potential role of leukocyte subtypes’ ratios, mean platelet volume (MPV), and red cell distribution width (RDW) as markers during the inflammatory process. This study’s authors hypothesized that neutrophil lymphocyte ratio may be affected by the severity of HS, which is considered to be caused by dysregulation of the immune system. Therefore, the authors aimed to compare neutrophil lymphocyte ratios (NLRs) and other hematological parameters in different stages of HS.

The authors retrospectively analyzed the records of all patients diagnosed with HS in the study site’s hospital between January 1, 2012 and December 31, 2014. Patients with other chronic inflammatory diseases or incomplete data were excluded. The hematological parameters including hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), RDW, white bloods cells (WBCs), neutrophils, lymphocytes, platelets, and MPV were recorded, and NLRs were calculated. Basic patient demographics and involved areas were also recorded. As shown in Table 1, after verification of the diagnosis with pathology records, the patients were categorized into 3 groups according to the Hurley staging system, which has been used as a basis for the planning therapeutic approach for patients with HS.²  

Statistics. Chi-square (Monte Carlo) was used to analyze the gender distribution in Hurley stages, because the cells in the relevant r x c contingency table had small expected values.⁹ Because there was 1 nominal variable and 1 measurement variable, and the nominal variable divided the measurements into 3 groups, the parameters including MCH, MCHC, and NLR were analyzed with one-way analysis of variance (ANOVA).¹⁰ Depending on the test of homogeneity variance, MCH and NLR were further analyzed with Tamhane’s T2 post hoc test because equal variances were not assumed, while MCHC was analyzed with Tukey honest significant difference test because equal variances were assumed.¹⁰ Kruskal-Wallis test was used to analyze hemoglobin, hematocrit, MCV, RDW levels, WBC, neutrophil, lymphocyte, platelet counts, and patient ages since the measurement variable did not meet the normality assumption of a one-way ANOVA.¹⁰ A value of P < .05 was considered statistically significant.

General features of the patients. Of 42 patients with HS, 35 were eligible for the study. Three patients were excluded because of insufficient data, whereas 4 patients were excluded due to other chronic inflammatory diseases (rheumatoid arthritis [n = 2], Crohn’s disease [n = 1], and familial Mediterranean fever [n = 1]). The eligible patients were categorized into 3 groups according to the Hurley staging system (stage I [n = 12], stage II [n = 11], and stage III [n = 12]) (Table 2). The majority of the patients were male, and the male sex demonstrated a statistically significant association with greater disease severity (P = .004). The mean age of stage III was greater than stage I and stage II (P = .02). The involved anatomic areas are presented in Table 2. 

Hemogram findings are presented in Table 3. Hemoglobin, MCV, and MCH levels were greater in stage I than stage III (χ² = 7.15, P = .028; χ² = 9.28, P = .010; F = 6.13, P = .006, respectively). On the other hand, WBC and neutrophil counts were higher in stage III than stage II (χ² = 6.05, P = .049; χ² = 13.35, P = .001, respectively), and lymphocyte counts were higher in stage II than stage III (χ² = 11.85, P = .003). The NLR of stage I was detected to be significantly higher than stage II and lower than stage III (F = 17.75, P < .001). 

The study’s main finding was that WBC and neutrophil counts were higher in stage III than stage II, while lymphocyte counts were lower in stage III than stage II. The NLR in stage I was significantly higher than stage II and lower than stage III. Another finding was that hemoglobin, MCV, and MCH levels were greater in stage I than in stage III. 

Early studies^11-15 suggested HS was an infectious disease. In 1977, Dvorak et al¹¹ reported there was no deficiency in host defense. However, recently HS has been associated with Crohn’s disease and pyoderma gangrenosum, which suggests immune dysfunction may play an essential role in the pathogenesis of HS.^12,13 Observational studies,^14,15 which showed improvement with antitumor necrosis factor (TNF)-α treatment for HS, also support this theory. 

Leukocyte count, its subtypes, and the ratio of absolute neutrophil count to lymphocyte count have been reported as inflammatory markers in different types of inflammatory diseases such as myocardial infarction, thromboembolic stroke, chronic kidney disease, inflammatory bowel disease, chronic obstructive pulmonary disease, and familial Mediterranean fever.^5,6,16-19 Studies on the pathogenesis of HS^20-23 demonstrated controversial findings about the frequency of T cells in the skin of patients with HS. While some studies have shown an elevated T cell count, O’Loughlin et al²⁰ reported
a reduced T lymphocyte count in patients with moderate-to-severe HS. In the present study, the authors observed higher neutrophil counts in stage III than stage II, while lymphocyte counts were higher in stage II than stage III, which can be interpreted as an inflammatory response change related to abscess formation. It was remarkable the NLR of stage I was detected as being significantly higher than stage II and lower than stage III.

Chronic anemia has been reported to be associated with HS. Tennant et al²⁴ assumed anemia was caused by chronic inflammatory processes. Elevated levels of interleukin (IL)-1β, IL-10 and TNF-α have been shown in HS, and it is believed that anemia in patients with HS is caused by these pro-inflammatory cytokines.^25,26 In this study, levels of hemoglobin, MCV, and MCH were lower in stage III than in stage I; however, the authors did not observe any significant difference in RDW values. There was no significant difference in platelet counts and MPV levels between the stages.

The major limitations of the study were a small sample size and the setting. Other limitations included the gender and age differences in the stages of HS. Additionally, gluteal and perianal involvements were more common in stage III. Moreover, the authors could not obtain much information about the disease durations in patients and the extent of the involved areas, which may also affect the hematological parameters. Another important point is that the correlation of some results with Hurley staging does not mandate causation. 

As a result, the authors have observed differences in systemic neutrophil and lymphocyte counts and the NLRs between the stages of HS, which may contribute to the previously proposed pathogenesis of HS. While lymphocytes were dominant in the inflammatory response in stage II, neutrophils were preponderant in stage III. The authors believe this information may influence the therapeutic approaches to HS, including immunomodulation and surgery. Additionally, the authors observed significant differences in the NLR between all 3 stages. Further studies may provide the NLR intervals for recognition of the Hurley stages, so that it may become an objective guide for appropriate treatment.

From the Eskişehir Osmangazi University, Medical School, Eskişehir, Turkey

Address correspondence to:
Necdet Fatih Yaşar, Asst. Prof.
Eskişehir Osmangazi University
Medical School
Eskişehir, Turkey
nfyasar@gmail.com

Disclosure: The authors disclose no financial or other conflicts of interest.