Diagnosis of Diffuse Large B-Cell Lymphoma

Diagnostic Methods

1. Confirmatory diagnosis through tissue examination The confirmatory diagnostic method for various lymphomas, including diffuse large B-cell lymphoma, is pathological tissue examination. A tissue examination is a test in which some tissue is obtained from an enlarged lymph node or an extranodal lesion mass that has grown due to lymphoma infiltration. The tissue is then thinly sliced, mounted on a glass slide, and appropriately stained. After that, a pathologist directly observes the shape of the cells in the tissue under a microscope. Usually, the process begins by checking the cell appearance through basic staining (H&E staining) to see whether lymphoma is suspected, and then special stains (immunohistochemical staining) for proteins that are expressed differently on the cell surface in each lymphoma are performed to determine what type of lymphoma it is.

Tissue examination methods include excisional biopsy, in which the entire lymph node or extranodal lesion is surgically removed and examined; needle biopsy, in which the lesion is punctured with a thin needle and some tissue is obtained through the groove at the tip of the needle; and incisional biopsy, in which part of the tissue is obtained by other methods.

Even within the same lymphoma, treatment methods and prognosis differ depending on the subtype, so an accurate subtype diagnosis is important. For this, various special stains must be performed sufficiently. In addition, viewing the entire lymph node infiltrated by lymphoma rather than just part of it is very helpful for an accurate pathological diagnosis, so excisional biopsy is preferred whenever possible. If excisional biopsy is difficult because of the lesion’s location, a needle biopsy is performed as a secondary option. In such cases, sufficient tissue needed to confirm the subtype may sometimes not be obtained, and a repeat test or surgical tissue examination may be necessary.

2. Various tests for staging After confirmation through tissue examination, or before confirmation if lymphoma is strongly suspected, tests are performed to determine the extent to which lymphoma has spread throughout the body, that is, staging tests.

Because lymphoma can spread throughout the body, computed tomography (CT) scans are performed of the neck (cervical region), chest (thorax), and abdomen and pelvis. In addition, diffuse large B-cell lymphoma is a cancer in which positron emission tomography is very helpful for staging and for evaluating treatment response afterward, so PET/CT is performed at the time of initial diagnosis and when assessing treatment results. In addition, additional imaging tests such as magnetic resonance imaging (MRI) may be performed for specific areas where lymphoma involvement is suspected.

About 10–15% of patients with diffuse large B-cell lymphoma have lymphoma involvement of the bone marrow, so all patients undergo a bone marrow examination. A bone marrow examination consists of two parts: drawing bone marrow fluid from the marrow area with a syringe and obtaining part of the bone marrow tissue to make slides for analysis. In adults, this is usually done from the back part of the pelvic bone. To obtain more accurate results, it is mostly performed on both the left and right sides.

3. Other tests In some patients with diffuse large B-cell lymphoma, the central nervous system, which consists of the brain and spinal cord (the bundle of nerves originating from the brain located inside the vertebrae), may be involved by lymphoma. In this case, the prognosis is poor and special additional treatment is required. If there are any symptoms suggesting brain or spinal cord involvement, such as severe headache, severe dizziness and vomiting caused by it, visual abnormalities, or paralysis symptoms due to spinal compression, a cerebrospinal fluid test is performed. Even if there are no symptoms, a cerebrospinal fluid test is performed in the following cases because there is a possibility of central nervous system involvement:

• If there is a lesion in the sinuses, testicles, retroperitoneum, or epidural area
• If the serum LDH level is elevated
• If there is bone marrow involvement or if HIV infection is present

Rituximab, a targeted therapy used to treat diffuse large B-cell lymphoma, and steroid preparations can easily trigger reactivation of hepatitis B in hepatitis B carriers. Therefore, at the time of diagnosis, blood tests are performed in all patients to check whether they are hepatitis B carriers. If the patient is already known to be a carrier or is newly confirmed to be a carrier, more detailed tests related to hepatitis B are performed, and antiviral medication is taken preventively.

So far, we have explained the diagnosis of diffuse large B-cell lymphoma. In the next part, we will look at the treatment of diffuse large B-cell lymphoma.

Source: Korea Disease Control and Prevention Agency National Health Information Portal