Patients suspected to have lymphoma based on the clinical assessment during the initial general practitioner visit should be immediately referred to a specialist for diagnosis.

For patients where there is less of an immediate concern, or a lower index of suspicion, further examinations/investigations by the general practitioner should include (but is not limited to):

• blood tests to assess organ dysfunction, such as a full blood examination with film and sometimes flow cytometry, urea and electrolytes, calcium and urate, liver function and lactate dehydrogenase (LDH) tests, beta 2 microglobulin, erythrocyte sedimentation rate and C-reactive protein (blood tests indicating organ dysfunction require further examination)
• serology to exclude infectious diseases including Epstein-Barr virus, human immunodeficiency virus and others is often needed (note that laboratory tests can indicate Hodgkin lymphoma and DLBCL may be present, but normal results do not indicate lymphoma absence)
• imaging of the affected area using ultrasound, x-ray and computed tomography (CT) scans, as appropriate
• biopsy, as appropriate
• a fine-needle aspiration is rarely discriminatory in this setting; a core biopsy may be appropriate (note that a negative fine-needle aspiration and normal core biopsy in the presence of a highly suspicious clinical case cannot indicate lymphoma absence) (Karimi-Yazdi et al. 2014)
• a period of observation of up to four weeks for patients without significant or progressive symptoms.