**5. Investigations**

Complete history and physical examination; inquiry about B symptoms, human immunodeficiency virus risk, infections, autoimmune diseases, immunosuppressive therapy.

Complete blood cell count and peripheral smear examination including hemoglobin, total leukocyte count with differential and platelet count.

Biochemistry profile—lactate dehydrogenase; alkaline phosphatase, uric acid, creatinine, calcium, and albumin.

Imaging—computed tomography of chest, abdomen, pelvis, and neck, Selected radiologic procedures as clinically appropriate (e.g., gallium, positron emission tomography scan, magnetic resonance imaging, ultrasound, bone scan).

Bone marrow aspiration and biopsy—morphology, immunophenotyping, cytogenetics, molecular tests, and gene rearrangement studies.

Lumbar puncture with cytology in patients with CNS involvement.

Gastrointestinal endoscopy for patients with Waldeyer ring involvement or abdominal symptoms.

Cytologic assessment of third space fluids (pleura, peritoneum) in case of effusions.

Other blood evaluations: levels of ß 2-microglobulin and cytokines (interleukin-2 receptor, tumor necrosis factor).
