Clinical analysis of generalized pustular psoriasis in Chinese patients: A retrospective study of 110 patients

Abstract Generalized pustular psoriasis is an immune‐mediated dermatologic condition characterized by widespread, sterile, subcorneal pustules. However, limited information exists regarding the clinical course of generalized pustular psoriasis. This study aimed to examine the precipitating factors, clinical manifestations, laboratory data, relapse patterns, and prognosis of generalized pustular psoriasis at our hospital and to improve the diagnosis and treatment. A retrospective analysis was conducted for generalized pustular psoriasis in our department from 2014 to 2019. In total, 110 patients were included in our study (mean age 46.5 years). The female:male ratio was 1:2.7. Ninety‐four (85.5%) had a psoriasis vulgaris history, 12 (10.9%) had a psoriatic arthritis history, five (4.5%) had an erythrodermic psoriasis history, and 16 (14.5%) had a family history of psoriasis. Eleven (10.0%) cases were triggered by infections and 17 (15.5%) were caused by the sudden discontinuation of systemic drugs. During hospitalization, the proportion of patients with hyperlipidemia was higher after acitretin treatment than before acitretin treatment (P < 0.05). The proportion of patients with abnormal liver function was higher after methotrexate treatment than before methotrexate treatment (P > 0.05). The onset age of generalized pustular psoriasis was younger in patients without prior psoriasis (P < 0.05). The mean time to pustular clearance was shorter in patients with prior psoriasis than in those without prior psoriasis (P > 0.05). Moreover, among patients with fever, skin lesion clearance rates were highest in the biological agent group (81.8%). However, among patients without fever, skin lesion clearance rates were highest in the acitretin group (86.7%). No patients presented serious complications or died. Our study presents the detailed clinical course of generalized pustular psoriasis in Chinese patients. These results will help to better understand and treat generalized pustular psoriasis.


| INTRODUC TI ON
Psoriasis is a chronic, immune-mediated, inflammatory skin disease that is not uncommon in adults and affects 1%-3% of the global population. 1 In particular, generalized pustular psoriasis (GPP) is a rare variant of psoriasis that is characterized by the widespread eruption of sterile, subcorneal pustules and epidermal scaling accompanied by signs of toxicity, fever, and leucocytosis. GPP has a significant negative impact on the quality of life and is even potentially lifethreatening in some severe cases.

| ME THODS
A retrospective study was conducted in patients with GPP admitted to Shanghai Skin Disease Hospital in China from January 2014 to December 2019. All data used were from inpatient medical records.
GPP was diagnosed based on history, characteristic skin lesions, and related laboratory examinations that met the international criteria 3 and was confirmed by at least two dermatologists. The clinical features and course were analyzed according to the presence of previous plaque psoriasis and body temperature. Characteristic information including age, sex, the age of onset, onset season, family history of psoriasis, previous history of psoriasis vulgaris (PsV)/ psoriatic arthritis (PsA)/erythrodermic psoriasis (EP), inducing factor, laboratory data, treatments, and hospitalization days was obtained from each patient. This study was approved by the research ethics committee of Shanghai Skin Disease Hospital.  In our study, 58 patients suffered from fever and their body temperature was 38-41ºC. Forty-three patients underwent blood culture tests, which were all negative. In 53 patients, the mean time for body temperature to return to normal was 8.71 ± 4.58 days. The body temperature of the remaining five patients did not return to normal before discharge. Compared with patients with fever, the mean time for pustular clearance was shorter in patients without fever (11.1 ± 7.4 vs 7.4 ± 5.0, P < 0.05). The proportion of patients with hypoalbuminemia, hypocalcemia, leucocytosis, and abnormal liver function was higher in patients with fever than in patients without fever (77.6% vs 48.1%, P < 0.05; 52.7% vs 25.5%, P < 0.05; 69.0% vs 31.4%, P < 0.05; 22.4% vs 9.6%, P > 0.05). Moreover, in patients with fever, the rate of achieving skin lesion clearance was the highest in the group treated with biological agents (81.8%). However, in patients without fever, the rate of achieving skin lesion clearance was the highest in the acitretin group (86.7%). These data are shown in Table 3. Table 4, 98 patients were treated with systemic acitretin and the dose ranged from 0.5 to 1.0 mg/kg/day (the maximum dose did not exceed 40 mg/day). However, 19 patients were switched to other treatments because of treatment failure, one patient was discharged temporarily due to stomach discomfort, and eight patients still had a few pustules or scabs on the day of discharge. The mean time for body temperature to return to normal was 5.7 ± 6.0 days, the mean hospitalization time was 15.4 ± 5.6 days, and the mean time for pustule clearance was 8.5 ± 5.2 days. During hospitalization, the proportion of patients with hyperlipidemia was higher after treatment than before treatment (47.

| DISCUSS ION
In our study, the disease started at a mean age of 43.4 years, which is similar to the 40-60 year age range reported by Baker and Jin. 4,5 The mean onset age of pediatric patients was 10.2 years, which is slightly higher than the age of 6.9 years that Wei Liu observed in *P values represent a comparison between GPP patients with a history of plaque psoriasis vs GPP patients without a history of plaque psoriasis. P < 0.05 is considered statistically significant.

TA B L E 2
Clinical features of patients with GPP with or without previous PsV and the total efficacy rate was 71.4%, which was slightly lower than the 83.7% efficacy rate reported by Teng Jiayong. 8 The proportion of patients who showed pustular clearance was higher in patients without fever than in patients with fever, which proved that body