Clinical Characteristics of Pruritus in Patients with Scalp Psoriasis and Their Relation with Intraepidermal Nerve Fiber Density

BACKGROUND The scalp is frequently affected in psoriasis patients, and pruritus can adversely affect the quality of life of affected patients. Few studies have assessed pruritus in scalp psoriasis. OBJECTIVE To determine the correlation among the clinical characteristics of pruritus, psoriasis scalp severity index (PSSI), and intraepidermal nerve fiber (IENF) density in psoriatic scalp lesions. METHODS Eighty patients (53 men, 27 women; mean age, 46.4 years; mean PSSI, 19.9) with scalp psoriasis were evaluated by using the PSSI and the Leuven itch scale. Biopsies were obtained from the lesional and nonlesional skin of 19 patients (10 men, 9 women; mean age, 37.8 years; mean PSSI, 25.8). Immunofluorescence staining of protein gene product 9.5 was performed to determine the IENF density. RESULTS Sixty-four patients (80%) complained of pruritus associated with scalp psoriasis, which negatively affected their quality of life to varying degrees. A moderate positive relation between PSSI score and pruritus intensity was identified (r=0.225 and p=0.044). The IENF density in psoriatic lesions was significantly higher than that in the nonlesional scalp (6.2±1.2 vs. 4.2±1.6, p<0.001). However, the correlations between IENF density and PSSI score, and IENF density and pruritus intensity were insignificant. CONCLUSION These results indicate that pruritus prevalence is high in patients with scalp psoriasis, and pruritus considerably influences the patients' daily lives and quality of life. In addition, high IENF density in psoriatic scalp lesions may play a role in the development of pruritus in scalp psoriasis.