Primary Cutaneous Diffuse Large B-cell Lymphoma, Leg Type with Immune Thrombocytopenia as the First Primary Presentation

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) is a rare aggressive vari-ant of non-Hodgkin lymphoma (NHL). It is also clinically uncommon for NHL to primarily manifest as immune thrombocytopenia (ITP). We report a rare case of PCDLBCL-LT, which was misdiagnosed as primary refractory ITP. He achieved a complete remission of ITP by cyclophosphamide. Five months later, the patient developed recurrent erythematous plaques that disseminated to his entire body, accompanied by extracutaneous lesions. Skin biopsy indicated PCDLBCL-LT. After one cycle of CHOP regimen, the patient's condition improved. When encountering refractory ITP, it is important to identify potential underlying causes.