Primary cutaneous B-cell lymphomas- clinical and histopathologic features, differential diagnosis, and treatment.

Cutaneous B-cell lymphomas (CBCLs) are a heterogeneous group of diseases that can have variable presentations, prognoses, and treatments. The proper identification of a CBCL hinges on proper histopathologic and clinical evaluation. Comprising 25% to 30% of the primary cutaneous lymphomas, incident cases of CBCL are rare. Given the variable natural history of the CBCL, proper classification is critical so that patients are treated appropriately. CBCLs can be divided into 2 main groups: indolent and aggressive. Indolent CBCLs include primary cutaneous follicle center lymphoma and primary cutaneous marginal zone lymphoma. These subtypes usually do not affect a patient's lifespan but can lead to substantial symptomatology, prompting the need for treatment. The aggressive subtypes of CBCL include diffuse large B-cell lymphoma leg type and intravascular large B-cell lymphoma. These are treated as systemic lymphomas, and their prognoses are not as good. In this article, we discuss the clinical features, differential diagnoses, histopathologic features, and treatment options for each of the 4 types of CBCL. The proper categorization of these diseases can allow physicians to properly treat a patient with CBCL, including the avoidance of unnecessary therapy.