A 22-year-old male patient visited the Department of Dermatology of the First Affiliated I Iospital of Zbengzhou University on October 31,2016 due to dark red papules,nodules,pustules and cysts on the face,neck,back and in the axillary and inguinal regions for 6 years,and multiple dark purple plaques and ulcers on bilateral lower limbs for 1 year.Six years ago,the patient was diagnosed with acne in other hospital,and no treatment was given.One year ago,multiple purple plaques occurred on the bilateral lower limbs,which then ruptured and progressed into ulcers with diameters of 1-12 cm.On May 9,2002,the patient visited the Department of Pediatric Medicine of the First Affiliated Hospital of Zhengzhou University due to the left knee joint swelling and pain for half a year.Laboratory examination showed negative rheumatoid factor,and smear examination of the left knee joint effusions revealed that there were neutrophils and a small amount of lymphocytes and monocytes in the joint effusions,and no abnormal cells were observed.Then,the patient was diagnosed with pyogenic arthritis of the left knee.Physical examination at admission showed poor general condition,walking difficulty,slightly increased blood pressure of 142/92 mmHg (1 mmHg =0.133 kPa),multiple purple plaques on the bilateral lower limbs with central ulcer formation.Histopathological examination of ulcer margin on the lower limbs showed ulceration,intercellular edema and infiltrating neutrophils in the epidermis,and edema,focal erythrocyte extravasation,diffuse infiltration of neutrophils,lymphocytes and histiocytes in the superficial and middle dermis.Clinical manifestations and pathological features confirmed a diagnosis of pyoderma gangrenosum.There were extensive inflammatory papules,pustules,abscesses and cysts on the face,neck,waist and back,and a small amount of dark red nodules on the axillary and inguinal regions,which were consistent with cystic acne and hidradenitis suppurativa.As PSTPIP1 gene sequencing showed,no mutations were found in exon fragments,while compound heterozygous mutations c.36 + 68 G ＞ A,c.137 + 47 G ＞ C and c.562 + 114 C ＞ G her were found in intron fragments.Among 100 healthy controls,45 carried the same mutations.So,these mutation sites were considered to be polymorphic sites,and the pathogenicity of these mutations was still unclear.Finally,the patient was diagnosed with PAPASH syndrome.The patient was treated with methylprednisolone,cefminox,isotretinoin and thalidomide,and the lesions were markedly improved after 2 weeks.Now the patient was still followed up.