Abstract: 【Abstract】 To report four cases of primary cutaneous CD30+ lymphoproliferative disorders （pcCD30+LPDs） with DUSP22 rearrangement exhibiting a biphasic histological pattern. The clinicopathological features of pcCD30+LPD patients were analyzed. Four patients visited the Hospital of Dermatology of the Chinese Academy of Medical Sciences from 2018 to 2022 for treatment or consultation, including 3 female patients and 1 male patient, aged 51 to 73 years, with skin lesions manifesting as papules or nodules. Solitary lesions were found in 2 patients, and multiple lesions were observed in the other 2 patients. The affected sites were the forehead, lower jaw, forearms, neck and limbs. Histopathological examination revealed a biphasic pattern characterized by a diffuse infiltration of lymphocytes in both the dermis and epidermis. Pautrier-like microabscesses were observed in 1 case. There was no obvious inflammatory background in the dermis. An immunohistochemical study revealed a biphasic pattern of CD30 expression, with strong diffusion in dermal tumor cells, but weaker staining in the epidermal counterpart. CD3+CD4-CD8- phenotype T cells were found in 3 patients, and the remaining patient had a CD3+CD4+CD8+ phenotype. All cases had a high proliferative rate （70% - 90%） by Ki-67 staining. The cytotoxic marker, B cell markers and anaplastic lymphoma kinase were uniformly absent. Fluorescence in situ hybridization assay for the DUSP22-IRF4 locus on 6p25.3 showed a split signal in all patients. By observation, local resection, radiotherapy, or systemic drug therapy, the lesions all subsided in the 4 patients.

Key words: Lymphoma, T-cell, cutaneous, Lymphoma, primary cutaneous anaplastic large cell, Lymphomatoid papulosis, CD30 positive lymphoproliferative disorders