Hospitalized generalized pustular psoriasis vs. acute generalized exanthematous pustulosis: A comprehensive analysis of clinical manifestations and treatment outcomes

To the Editor: Generalized pustular psoriasis (GPP) is a rare, chronic, and life-threatening condition characterized by widespread eruption of sterile pustules.[1,2] The mortality rate of GPP is 39.2 per 1000 person-years, with over half of the patients requiring hospitalization.[3] Another non-follicular pustular disease, acute generalized exanthematous pustulosis (AGEP), is currently defined as a rare, acute, and severe cutaneous adverse reaction.[4] The confusion between GPP and AGEP remains a clinical challenge, highlighting the urgency for additional diagnostic markers to distinguish between these two conditions. Therefore, we aim to provide analytical insights that facilitate the diagnosis of these two distinct dermatological entities. This was a cross-sectional study covering GPP and AGEP hospitalized patients admitted to Xiangya Hospital between January 1, 2013, and August 31, 2023. The study was approved by the Ethics Committee of Xiangya Hospital (No. 202203092). The requirement for informed consent was waived by the ethics committee due to the retrospective nature of the study and as all data were anonymized. All patients were diagnosed based on the International Classification of Diseases Version 10 (ICD-10). The terms used for GPP identification were in accordance with the European consensus.[5] The inclusion criteria for GPP patients were those in an acute form with persistent symptoms for less than 60 days, while the inclusion criteria for AGEP patients were those diagnosed according to the EuroSCAR diagnostic scoring.[4] In total, 94 hospitalized patients with acute GPP and 54 hospitalized patients with AGEP were included. The GPP group had a higher proportion of males (54.3% [51/94] vs. 35.2% [19/54], P = 0.025, Table 1) than the AGEP group. The AGEP group had a larger proportion of patients who originated from non-outpatient pathways (25.9% [14/54] vs. 7.4% [51/94], P = 0.002), and were admitted more shortly after the symptom onset (median disease duration: 6.5 days vs. 10.0 days, P <0.001). Additionally, patients in the AGEP group had a higher proportion of allergic history (44.4% [24/54] vs. 21.3% [20/94], P <0.01). Cutaneous symptoms, such as pain, itching, and mucosal involvement, were presented similarly in both groups [Table 1], but burning occurred more frequently in the AGEP group (11.1% [6/54] vs. 2.1% [2/94], P = 0.05). Moreover, the GPP group exhibited a higher prevalence of high fever (39.4% [37/94] vs. 22.2% [12/54], P = 0.033), nail abnormalities (25.5% [24/94] vs. 1.9% [1/54], P <0.001), arthralgia (16.0% [15/94] vs. 3.7% [2/54], P = 0.024), oedema (37.2% [35/94] vs. 16.7% [9/54], P = 0.008), and hypoproteinemia (74.5% [70/94] vs. 59.3% [32/54], P = 0.054). Table 1 - Demographics and clinical characteristics of GPP and AGEP patients. Items GPP group (n = 94) AGEP group (n = 54) P Male 51 (54.3) 19 (35.2) 0.025 Age (years), Median (IQR) 44.0 (22.0) 36.5 (33.0) 0.396 Age category <18 years 12 (12.8) 8 (14.8) 18–64 years 77 (81.9) 39 (72.2) ≥65 years 5 (5.3) 7 (13.0) Weight (kg), mean (SD) 57.47 (1.68) 57.08 (2.83) 0.900 Current or former smoker 22 (23.4) 6 (11.1) 0.066 Current or former alcohol intake 13 (13.8) 3 (5.6) 0.119 Disease durations, days, Median (IQR) 10.0 (13.0) 6.5 (7.0) <0.001 Allergic history 20 (21.3) 24 (44.4) 0.003 Family history 5 (5.3) 0 0.211 Cutaneous symptoms Pain 26 (27.7) 10 (18.5) 0.212 Itching 78 (83.0) 39 (72.2) 0.122 Burning 2 (2.1) 6 (11.1) 0.051 Mucosal involvement 7 (7.4) 7 (13.0) 0.270 Extracutaneous symptoms Fever (temperature ≥39°C) 37 (39.4) 12 (22.2) 0.033 Nail abnormalities 24 (25.5) 1 (1.9) <0.001 Arthralgia 15 (16.0) 2 (3.7) 0.024 Oedema 35 (37.2) 9 (16.7) 0.008 Swollen lymph nodes 7 (7.4) 1 (1.9) 0.284 Liver abnormalities 21 (22.3) 12 (22.2) 0.987 Hypoproteinemia 70 (74.5) 32 (59.3) 0.054 Medication during the hospitalization Systemic corticosteroids 15 (16.0) 43 (79.6) <0.001 Acitretin 75 (79.8) 4 (7.4) <0.001 Methotrexate 14 (14.9) 1 (1.9) 0.011 Cyclosporine 14 (14.9) 1 (1.9) 0.011 Plasma exchange 1 (1.1) 2 (3.7) 0.623 Intravenous immunoglobulin 3 (3.2) 1 (1.9) 1 Biologics 3 (3.2) 1 (1.9) 1 Systemic antibiotics 46 (48.9) 21 (38.9) 0.237 Laboratory index WBC (×109/L), Median (IQR) 9.70 (5.90) 12.35 (7.80) 0.007 Neutrophils (×109/L), Median (IQR) 7.20 (5.00) 9.40 (7.00) 0.009 Lymphocyte (×109/L), Median (IQR) 1.40 (1.00) 1.50 (1.00) 0.353 LMR, Median (IQR) 1.78 (1.33) 2.45 (2.27) 0.008 CRP (mg/L), Median (IQR) 81.70 (110.00) 28.30 (74.00) 0.001 PCT (ng/ml), Median (IQR) 0.21 (1.00) 0.13 (0) 0.018 ESR (mm/h), Median (IQR) 64.80 (35.51) 42.23 (24.12) <0.001 Calcium, mean (SD) 2.11 (0.20) 2.19 (0.13) 0.012 HDL (mmol/L), mean (SD) 0.92 (0.32) 1.15 (0.30) <0.001 Triacylglycerol (mmol/L), Median (IQR) 1.13 (1.00) 0.96 (1.00) 0.046 Framingham, Median (IQR) 0.06 (0) 0.02 (0) 0.002 Outcomes Times of hospital admissions, Median (IQR) 1 (1) 1 (1) 0.113 Length of hospital stay (days), Median (IQR) 11 (7) 7 (6) <0.001 Intensive care unit admission 3 (3.2) 0 0.471 In-hospital mortality 1 (1.1) 0 1 Data are n (%) unless stated otherwise. AGEP: Acute generalized exanthematous pustulosis; CRP: C-reactive protein; ESR: Erythrocyte sedimentation rate; GPP: Generalized pustular psoriasis; HDL: High-density lipoprotein; LMR: Lymphocyte to monocyte ratio; IQR: Interquartile range; PCT: Procalcitonin; SD: Standard deviation; WBC: White blood cells. The observed comorbidities between the two groups were generally comparable. Relative to patients with GPP, patients with AGEP had a higher proportion of mild liver disease (24.1% [13/54] vs. 10.6% [10/94], P = 0.03, Supplementary Figure 1, https://links.lww.com/CM9/C503). Inflammatory biomarkers, including white blood cell (WBC) count (12.35 × 109/L vs. 9.70 × 109/L, P = 0.007), neutrophils (9.40 × 109/L vs. 7.20 × 109/L, P = 0.009), and lymphocyte to monocyte ratio (LMR) (2.45 vs. 1.78, P = 0.008), were significantly higher in the AGEP group, while other inflammatory biomarkers (C-reactive protein [CRP], procalcitonin [PCT], and erythrocyte sedimentation rate [ESR]) showed the opposite trend [Table 1]. Notably, the GPP group had lower albumin concentrations and lower albumin/globulin ratios, which may explain why patients with GPP are more likely to develop oedema. Among all recorded electrolytes, calcium was the only indicator with abnormality for both groups, with means of 2.11 ± 0.20 in GPP and 2.19 ± 0.13 in AGEP (P = 0.012). Interestingly, the GPP group exhibited lower high-density lipoprotein (HDL) levels, higher triacylglycerol levels, and higher Framingham scores than the AGEP group [Table 1]. Furthermore, the GPP group had a longer hospital stay than the AGEP group, with medians of 11 days vs. 7 days. The longer stay of hospitalization among GPP patients was found to be correlated with high fever (β: 3.11; 95% confidence interval [CI]: 0.69–5.54, Supplementary Table 1, https://links.lww.com/CM9/C503) and arthritis involvement (β: 2.68; 95% CI: 0.30–5.06). Additionally, for GPP patients, those treated with systemic antibiotics exhibited an even longer hospital stay (β: 3.96; 95% CI: 1.67–6.26). As for AGEP patients, only WBC count (β: 0.41; 95% CI: 0.01–0.80, Supplementary Table 2, https://links.lww.com/CM9/C503) and skin infections (β: 15.40; 95% CI: 4.30–26.5) were positively associated with the length of hospital stay. Our study revealed that extracutaneous symptoms, with laboratory indicators, are specific differential diagnostic factors to distinguish between GPP and AGEP. The extracutaneous signs that are helpful for differentiating these two conditions include high fever ≥39°C, nail abnormalities, arthralgia, and oedema. Biochemical indicators showed differences in inflammation and metabolic markers between the two groups, revealing systemic conditions beyond skin problems. Overall, we concluded that high fever, arthritis involvement, WBC count, and skin infections are associated with a longer hospital stay. Like other studies based on hospitalization data, this work is subject to several limitations. First, we did not acquire the information on histopathologic features and follow-up records. Second, our research was based on a cohort from a single center and included only hospitalized patients. Third, sample size is a common challenge in rare conditions, with no exception for our study. As the incidence rate of AGEP is significantly lower than that of GPP, we were unable to include the same number of patients for the two groups. Funding This work was supported by grants from the National Key Research and Development Program of China (No. 2023YFC2508105), the National Natural Science Foundation of China (Nos. 82373484, 82173426, and 82473533), and the Natural Science Foundation of Hunan Province (No. 2023JJ30984). Conflicts of interest None.

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