Once abnormalty in blood test is detected further tests are carried out on the patient to delve into the complaints. The following methods help to come to a conclusive diagnosis.

Getting a proper
medical history from the patient

Recording the presenting symptoms in detail

A thorough
physical examination.
Blood tests are carried out for various parameters like blood cell count, sedimentation rate and blood biochemistry

A chest X-ray.

A
CT scan or an MRI scan involving the chest, abdominal and pelvic region helps to identify the spread of the disease

A
gallium scan or a
Positron Emission Tomography (PET) scan helps in studying and identifying the disease

A
bone marrow aspiration or sometimes a
bone marrow biopsy is carried out to confirm the presence of the disease.
These tests not only help in confirming the disease but also help in typing or classifying the disease and also to stage them.
A subtype of NHL,
Anaplastic Large-Cell Lymphoma (ALCL), harbors a close resemblance to
Lymphocyte-Depleted Hodgkin's Lymphoma (LDHL), which is a subtype of HL. Diagnosing these subtypes must be done with extreme care, as the treatment regimen for the two subgroups vary.