Background and Objectives: There are no studies regarding comparative analysis of hematological parameters in patients with psoriasis (PsO) and atopic dermatitis (AD), whereas studies examining serum biomarkers of immunity and inflammation in these entities are scarce and contradictory. We aimed to compare such parameters in patients with PsO and AD. Materials and Methods: Patients with PsO (n = 40) and AD (n = 40) were consecutively included in this cross-sectional study. Hematological parameters and biomarkers of immunity and inflammation (interferon-gamma (IFN-γ), interleukine (IL)-22 and C-reactive protein (CRP)) were determined. Results: While the mean corpuscular volume (MCV) was higher in the PsO group vs. the AD group (p < 0.05), there was no difference in the other examined parameters between groups. A higher neutrophil-to-lymphocyte ratio (NLR) was found in patients with AD > 50 years vs. patients with PsO of similar age (p < 0.05). Higher IL-22 levels were found in patients with AD < 50 years vs. patients with PsO of similar age (p < 0.05). Lower IL-22 levels were found in patients with AD > 50 years vs. patients with AD < 50 years (p < 0.05). Patients with PsO and with comorbidities had lower platelets (PLT), plateletcrit (PCT) and platelet-to-lymphocyte ratio (PLR), whereas lymphocytes, red cell distribution width-to-PLT ratio (RPR) and mean platelet volume/PLT ratio (MPR) were higher vs. PsO patients without comorbidities. Patients with AD and with comorbidities had lower PCT and PLR, whereas RPR was higher vs. AD patients without comorbidities. Conclusions: A higher pro-inflammatory state (i.e., higher NLR and IL-22) was found in AD vs. PsO in age-specific groups. A higher pro-inflammatory state (i.e., as reflected by platelet indexes) was found in both diseases with comorbidities.
