Rituximab and Dexamethasone in Treating Patients With Low-Grade Non-Hodgkin Lymphoma

Inclusion Criteria: * Patients must have histologically proven CD20+ low grade B cell lymphoma including follicular, marginal zone, monocytoid B cell, and lymphoplasmacytoid lymphoma; patients may be previously untreated or in relapse * Patients must have measurable disease with clearly defined margins assessed by physical exam with direct measurement (for cutaneous B-cell lymphomas), computed tomography (CT) or magnetic resonance imaging (MRI), defined as \>= 20 mm with conventional CT or MRI or \>= 10 mm using spiral CT scan * Absolute neutrophil count \>= 1000/mm\^3 * Hemoglobin \> 7 g/dl * Platelets \>= 100,000/mm\^3 * Serum creatinine =\< 2.5 mg/dl * Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) =\< 2x the upper limit of normal (ULN) * Karnofsky performance score \>= 70 % * Patient has signed an Institutional Review Board (IRB) approved informed consent form that conforms to federal and institutional guidelines Exclusion Criteria: * Patient has received rituximab therapy within 6 months of entry into protocol * Patient has received systemic steroid therapy within one month of entry into protocol * Patient has Intermediate or High Grade NHL, mantle cell lymphoma, chronic lymphocytic leukemia, or small lymphocytic lymphoma * Patient is pregnant or lactating * Patient is unwilling or unable to practice contraception during treatment and for one year thereafter * Patient has active central nervous system (CNS) disease * Patient has human immunodeficie…