A current view of the pathogenesis and treatment of primary cutaneous diffuse large B cell lymphoma - leg type.

Primary cutaneous diffuse large B cell lymphoma, leg type (PCDLBCL-LT) is an aggressive B cell extranodal variant of lymphoma present in the skin, typically without evidence of extra cutaneous spread at the time of diagnosis. PCDLBCL-LT accounts for 20% of all primary cutaneous B cell lymphomas (CBCL) and 5% of all primary cutaneous lymphomas (PCL). It is more common in the elderly (median age 75 years). The disease commonly manifests as rapidly-growing red to bluish often ulcerating, nodular tumors, plaques or violaceous nodules on one or both lower extremities. Only 10% to 15% of lesions develop in other areas. A prognosis of PCDLBCL-LT is poor, with a 5-year survival rate of 40 to 50%. The first-line treatment of PCDLBCL-LT includes immunochemotherapy, most commonly R-CHOP (rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, prednisone). In the case of a solitary lesion, excision or radiotherapy should be considered. Many patients demonstrate cutaneous relapses (70%) or systemic dissemination (50%). Recent studies have reported the use of Bruton's tyrosine-kinase (BTK) inhibitors, BCL2 inhibitors, immunomodulatory drugs and immune check-point inhibitors in treating relapsed or refractory patients. The study summarizes the current view of the pathogenesis, diagnosis and treatment of PCDLBCL-LT, including genetic abnormalities and novel targeted drugs.