• Clonal evolution
• Lymphoma
• Polymerase chain reaction
• Receptors, antigen, B‑cell
• Receptors, antigen, T‑cell

Primary cutaneous B cell lymphoma (PCBCL) is defined as B cell lymphomas that presents in the skin without any evidence of extra-cutaneous involvement at diagnosis. They are the second most common type of primary cutaneous lymphomas accounting for 25%-30%. Since the prognosis and treatment differ from systemic lymphomas involving the skin, differential diagnosis is very important. PCBCL is a heterogeneous group of disease comprising different B cell lymphomas with distinct treatment and prognosis. PCBCL is divided into 5 subclasses according to World Health Organization and European Organization of Research and Treatment of Cancer classification. Primary cutaneous marginal zone lymphoma and primary cutaneous follicle center lymphoma are indolent forms and often confined to skin at presentation and during the course of the disease. But primary cutaneous diffuse large B cell lymphoma, leg type and intravascular large B cell lymphoma are more aggressive forms that may disseminate to extra-cutaneous tissues. There is not a treatment consensus since they are rare entities. Local therapies like radiotherapy, surgery or intralesional steroids are options for localized disease in indolent forms. More disseminated disease may be treated with a systemic therapy like single agent rituximab. However combination chemotherapies which are used in systemic lymphomas are also required for aggressive PCBCL. Although indolent forms have relatively better prognosis, early relapses and disseminated diseases are mostly observed in aggressive form with a consequent poor prognosis.

• Primary cutaneous lymphomas
• Diagnosis
• Treatment
• Bcell lymphoma