A 14-year-old adolescent female was referred to our department in July 2021 with generalized pustular and erythematous on the trunk and extremities for a week. She did not complain of chills, fever or arthralgia, but complained of swelling and pain and mild itching in the lesions. During the history collection, the patient reported a history of recurrent pustules on the distal portion of the middle finger of her right hand since 2015, which had been diagnosed as onychomycosis and treated with oral and topical antifungal in local hospitals for half a year but failed in 2017. In the summer of 2019, pustules gradually developed to multiple fingers of her both hands (Figure 1A), she visited our clinic and had a biopsy, bacterial culture was sterile and the pathologic results confirmed the diagnosis of ACH (Figure 1B and C). Since then she received intermittently treatment with oral thiamphenicol, compound glycyrrhizin, minocycline, and traditional Chinese medicine (TCM), and so on, combined with topical halometasone and tazarotene cream. The treatment response was still poor and more fingers were involved. She returned to our out-patient three months ago. According to the patient's previous treatment response, in order to improve the treatment effect, taking into account the patient's age and economic status, oral cyclosporine (150mg/day, 4mg/kg/day) was given, but there was no improvement after one month of adherence, so she stopped the medication on her own. However, about half a month after she stopped cyclosporine, the symptoms of her fingers became worse and pustules also appeared on some of the toes of both feet, and erythema and pustules immediately appeared on the trunk and extremities. She was admitted and diagnosed with acute GPP at a local hospital where she had received detailed examination ruled out latent infections such as tuberculosis and hepatitis B. Then, she was treated with adalimumab (80mg at first dose). The erythema and pustules all over her body quickly subsided within a week after first injection. However, she did not receive subsequent injections, mistakenly believing that the disease had healed, and GPP relapsed a month after she stopped taking adalimumab. Then she was given adalimumab with an 80mg dose again at the local hospital, but her symptoms were still active a week later. After a second injection of 40mg adalimumab, instead of improving, her symptoms got worse. In desperation, she stopped further adalimumab injections and came to our out-patient again. 
Physical examination revealed widespread erythema and dense pustules on the trunk and limbs (Figure 2A-E). The erythema, swelling, crusting, focal erosion, and pustules were present on distal portions of all fingers (except the index and middle fingers of the right hand), as well as the fourth toe of the right foot and the third toe of the left foot. Nails of these fingers and toes were dystrophic and the nail plate were also studded with pustules (Figure 3A and B). Routine laboratory testing revealed white blood cell count of 15,860/muL (normal range, 4000-11,000/muL), neutrophil count of 12,670/muL (normal range, 2500-7000/muL) and neutrophil percentage of 79.9% (normal range, 50-70%), the count and percentage of eosinophils were both normal, serum levels of C-reactive protein (CRP) of 78.32 mg/L (normal range, 0-2 mg/L) and TNF-alpha of 162.00ng/mL (normal range, 7.4-15.4 ng/mL). The immunological laboratory tests including antinuclear antibodies, thyroid autoantibodies, rheumatoid factors, complement and so on were all normal. The thorax scanned by computed tomography (CT) and abdominal ultrasound showed no obvious abnormalities. Tuberculin purified protein derivative (PPD) skin test was normal. Hepatitis-virus-related tests were also normal. The family history of the patient was unremarkable for psoriasis or other inflammatory pathologies.  
Based on the patient's history of ACH, skin lesion characteristics and laboratory examination, the diagnosis of acute GPP was clear, with a Generalized Pustular Psoriasis Physician Global Assessment (GPPGA) total score of 4. Based on her previous experience with adalimumab, the patient and her guardians strongly refused to be treated with any biologics again. Therefore, we formulated a regular regimen of NB-UVB phototherapy combined with oral acitretin (20mg/day), which was accepted by the patient and her guardians. Due to lack of suitable skin areas for UVB minimal erythema dose (MED) testing, the patient was treated with NB-UVB (SS-10, Shanghai Sigma High Technology Co., LTD.) with an empirical starting dose of 300 mJ/cm2 (on the basis of Fitzpatrick skin type III), 3 times a week, and the dose is increased by 0-100 mJ/cm2 each time, depending on the skin reaction after each irradiation, and the maximum single dose did not exceed 3000 mJ/cm2. Surprisingly, the erythema and pustules on her trunk and extremities almost disappeared after two weeks of treatment. The patient was satisfied with the treatment response and was willing to continue the treatment. After another two weeks of treatment, the lesions all over her body had totally subsided, leaving only pigmentation (Figure 2a-e). Symptoms of fingers and toes also improved (Figure 3a and b). The GPPGA total score had been reduced to 1. NB-UVB was then reduced to once a week and the dose of acitretin was reduced to 10mg/day. There has been no recurrence of eruptions after more than 1 year of follow up.