Primary cutaneous anaplastic large cell lymphoma with over-expressed Ki-67 transitioning into systemic anaplastic large cell lymphoma: A case report

BACKGROUND: Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) differs from systemic anaplastic large cell lymphoma (sALCL) in cell biological behavior, clinical features, treatment, and outcome. PC-ALCL has been reported to rarely transition into sALCL, but the underlying mechanism is not clear. Here we report such a case with certain characteristics that shed light on this. CASE SUMMARY: Herein, we report a 43-year-old male with symptoms of a skin nodule and histologically confirmed PC-ALCL with high expression of Ki-67. After three months of observation, two skin nodules re-appeared with muscle layer involvement and was histologically confirmed as sALCL. Seventeen months after receiving six cycles of CHOP regimen, the patient had pain in the chest and back, cough, shortness of breath, and night sweats. This was confirmed as relapse of sALCL by immunohistochemistry and several organs, such as the lung were involved as shown by positron emission tomography/computed tomography. After four cycles of DICE plus chidamide regimens followed by auto-hematopoietic stem cell transplantation (ASCT), complete remission (CR) duration was achieved for twelve months while the patient was on maintenance with chidamide (20 mg) pills. CONCLUSION: This case had significantly high expression of Ki-67 when diagnosed as PC-ALCL initially and then transitioned into sALCL, which is rare. Auto-ASCT combined with demethylation drugs effectively maintained CR and prolonged progression free survival.