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Diagnostics of lymphoma

A positive development in diagnostics of malignant lymphoma has occurred in the last 10-15 years. New advances in immunology and cytogenetics/DNA technology and especially the use of immunophenotyping in diagnostics, have facilitated better classification and more confidence in the diagnosis.

Acute lymphoblastic leukemia and non-Hodgkins lymphoma have distinct clinical behavior. The degree of bone marrow infiltration determines whether a child with lymphoma is classified as non-Hodgkins stage IV or leukemia. In cases where there are over 25% lymphoblasts, the diagnosis is changed to leukemia. This applies to lymphoblastic disease of B- lineage or Tlineage.

Work-up

  • General status with emphasis on lymph node evaluation and hepato/splenomegaly. Findings are sketched on a body model and measurements are given.
  • Register B symptoms (weight loss, fever, pathological night sweats) or other defined general symptoms. Sedimentation rate, differential count of leukocytes, peripheral blood smear, creatinine, uric acid, Na, K, Ca, P, Mg, LD, ASAT, ALAT, alkaline phosphatase, bilirubin, CRP, albumin, ferritin, viral antibodies (CMV, HIV, hepatitis B and C, EBV, VZV, herpes simplex),TB testing. 
  • Urine test, urinalysis.

Imaging diagnostics 

The work-up is done in close collaboration between a pediatric oncologist, radiologist, and pathologist. For Hodgkins lymphoma, the oncologist responsible for the radiation therapy must be consulted during the work-up for accurate delivery of radiation therapy, if needed.

  • Ultrasound of suspicious node area and of the abdomen focusing on liver, spleen or para-aortal lymph nodes may be helpful.
  • Thoracic X-ray is routine. 
  • CT chest/neck/abdomen/pelvis is standard for lymphomas. 
  • CT spine for clinical tumor in spinal column if the patient is symptomatic. 
  • CT thorax (with axillae) is a standard test for work-up of lymphomas, especially since CT can assess lung parenchyma. For suspicion of infiltration of thoracic wall and/or pericardium, the CT thorax may be supplemented with MRI or ultrasound. 
  • A supplementary MRI of infiltrated areas in the neck, mediastinium, and retroperitoneum. This will be the basis for later follow-up with MRI and may allow a reduction of the radiation dose in the follow-up phase. Some locations are more suited for CT, especially those in the thorax/lungs and bone.
  • PET-CT should be done before starting treatment, especially for Hodgkins lymphoma. 
  • MRI of the head and spinal cord if there is suspicion of CNS infiltration. Correct use of contrast and signal sequences is important for optimal assessment of invasion of CNS and/or meninges. 
  • MRI of skeletal axis (column and pelvis) for suspicion of skeletal invasion or to assess the degree of generalization in bone/focal invasion in bone marrow. Skeletal scintigraphy normally does not have a place in the work-up of malignant lymphomas.

Histopathology examinations

The WHO classification uses a multiparametric approach to lymphoma classification. This includes morphology, immunophenotyping, molecular genetics, and, sometimes, virological and clinical data combined to arrive at a specific lymphoma diagnosis.

All specimens are sent unfixed to a pathologist.

 

 

Relevant clinical information that should be provided to the pathologist: 

  • Type of tissue 
  • Purpose of the test: diagnostic test, follow-up, suspicion of hematological disease.
  • Disease localization: lymph node, extra nodal, splenomegaly, hepatomegaly, leukemia
  • Disease history
  • Short case history: organ transplant, hepatitis C virus infection, long-term drug therapy, for example methotrexate, diphenylhydantoin
  • Pathologists should always be informed of contagious diseases: hepatitis, mycobacteria, HIV.  

Surgical biopsy

Even if the diagnosis is often made using needle biopsies, an open node biopsy should be performed  to visualize the tissue structure.  

Bone marrow aspiration/biopsy 

  • The most important reason for performing a bone marrow smear is to determine the number of blasts in the bone marrow to differentiate Non-Hodgkins lymphoma or leukemia.   
  • A bone marrow biopsy from the iliac crest should always be taken if there is suspicion of malignant lymphoma. Some types of lymphoma with often focal infiltration of bone marrow are best discovered by biopsy. Also, the histological picture provides diagnostic information that is not available from a smear. Biopsy is the only suitable method for discovering bone marrow infiltration from Hodgkin's lymphoma, and should be taken bilaterally from the hip bones in cases where detection of bone marrow infiltration has therapeutic consequences. 

Flow cytometry testing 

Flow cytometry testing has two significant advantages:

  • Multiparametric immunophenotyping gives a more exact immunophenotype of the cells. This is important for displaying co-expression of markers in the same cell population. A typical example of this is detecting restriction of immunoglobulin light chain in B cell neoplasias. 
  • This technique is also more sensitive for detecting small tumor populations.

It is strongly recommended that the flow cytometry operator assesses the morphology of the material before it is analyzed, or at least has the possibility of obtaining an assessment of the morphology in close proximity. The reason for this is to work more purposefully to determine the panel of markers to be used for flow cytometry and to determine the cell population to be gated upon using the cytometer. This will increase the value of the test.

Cytology/needle biopsy

Cytogenetic testing

Many types of malignant lymphoma are characterized by specific chromosome abnormalities; detection of these can clarify an otherwise difficult diagnosis.

 

Tumor localization and immunophenotype
Histology Immunophenotype Translocation Localization
B cell B

t(8;14)
t(8;22)
t(2;8)

Abdomen
Mediastinum
Lymfoblastic

Immature T
Pre B

t(10;14)
t(11;14)
t(1;14)
t(1;19)

Mediastinum
Pleura
Glands
Skeleton

LCAL T cell
Null cell
t(2;5)
t(1;5)
Glands
Hud
Skeleton
Mediastinum
Lung

Heart, lung, and renal function test 

Patients that will undergo chemotherapy and/or radiation therapy should have pretreatment testing of organ function.  

Organ function evaluation:

  • Heart function test (anthracyclines are cardiotoxic in high doses as is radiation)
  • Glomular filtration rate GFR (when medications that influence kidney function are used, for example, ifosfamide, or irradiation toward the kidney region)
  • Lung function test (irradiation to the thorax/lung and potentially lung-toxic chemotherapy such as bleomycin)

ENT examination

This test should be performed where there is infiltration of lymph nodes in the neck or infiltration of ENT area/Waldemeyers ring.

Dental examination

Patients who will undergo chemotherapy expected to cause serious bone marrow suppression should be examined by a dentist if there is a suspicion of possible infection foci. Parents/guardians should also be instructed on oral hygiene of the patient. A dental examination is obligatory before radiation to the jaw region, and also in patients with few/no teeth.

Sperm banking

Boys that have reached sexual maturity who are to be treated with chemotherapy or radiation below the diaphragm must be informed of sperm banking. If banking is appropriate, an appointment should be made at the Women's Clinic at Oslo University Hospital or St. Olav's Hospital.

Freezing ovarian tissue 

This is an experimental procedure that can be discussed for girls at high risk of infertility after treatment.

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