Preparation for the intervention and the role of laboratory diagnostics
Any surgical intervention aimed at harvesting lymphoid tissue requires thorough preliminary preparation. An absolute and non-negotiable condition prior to biopsy is a complete blood count. This analysis must include an accurate leukocyte differential count.
The main goal of this stage is to reliably rule out unjustified surgical trauma in lymphocytosis of completely different etiologies. The physician must ensure that lymphadenopathy is not associated with the following conditions:
- Hematological pathologies: chronic lymphocytic leukemia (CLL), monoclonal B-cell lymphocytosis, as well as various forms of acute leukemias.
- Infectious diseases: human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), cytomegalovirus (CMV). The exclusion list also includes pertussis, viral hepatitis, and toxoplasmosis.
- Other causes: post-vaccination and specific drug reactions, consequences of prolonged smoking, presence of a thymoma, or so-called "stress" lymphocytosis.
Surgical tactics and rules for handling biopsy specimens
During the initial examination of the patient, the standard is a full incisional or excisional biopsy. The obtained surgical material is sent for histological and immunohistochemical (IHC) examination. A crucial aspect is the interaction between the operating surgeon and the pathologist: the clinician is obliged to provide colleagues with a detailed excerpt from the patient's outpatient record or medical history.
Strict restrictions apply in surgical practice:
- Puncturing a lymph node for the purpose of cell suspension aspiration is strongly discouraged.
- Cytological examination (study of punctures, touch preps of the node, or lesions) serves exclusively as an auxiliary tool. Under no circumstances can it serve as a sufficient basis for a definitive diagnosis and nosological verification (for example, in suspected marginal zone lymphoma).
- Splitting the tissue material obtained during surgery between different laboratories is strictly unacceptable.
Specifics of core biopsy
Core-needle biopsy, or so-called core-biopsy, is not the method of choice for pathologies of the lymphatic system. Its use is permitted only in exceptional cases. Such situations include an extremely severe somatic condition of the patient or an anatomically hard-to-reach location of the tumor conglomerate.
If the surgeon decides in favor of a core-needle biopsy, they must clearly justify the impossibility of performing a classical excisional biopsy in the medical documentation. In order for the obtained biopsy specimen to be deemed suitable for a full pathomorphological examination, two physical criteria must be strictly met:
- The diameter of the biopsy needle used must be at least 16 G.
- The length of the obtained tumor infiltrate in the tissue core must be at least 1.5 cm.
Structure of the pathomorphological examination protocol
The final protocol of the biopsy or surgical material examination is the main medical document confirming the diagnosis. The scope of the required IHC examination is always determined directly by the pathologist during the primary histological study of the tissues. In a number of complex cases, molecular biological and genetic tests may be added to the baseline algorithm.
A properly compiled protocol must necessarily contain the following sections:
- Macroscopic description: a detailed characterization of all material submitted by the surgeon. If ready-made paraffin blocks and micropreparations are received for study, the specialist must indicate their exact quantity and all identification numbers of the objects.
- Histological description: a detailed characterization of the identified lymphoma. This section must record the type of tumor growth (e.g., diffuse or nodular), as well as detailed characteristics of the cellular composition (dominance of small or large cells, presence of a polymorphic cellular composition).
The PIG rule: Puncture is Excluded, Histology is mandatory. Cytology merely complements the picture, but never establishes a final diagnosis.
Class and exam questions
Can a lymphoma diagnosis be made based on cytology results alone?
No, cytological examination of punctures or touch preps is exclusively an auxiliary method. Histology with the use of IHC is mandatory for diagnosis verification.
In what cases is a surgeon permitted to perform a core-needle biopsy?
Only in exceptional situations: in an extremely severe condition of the patient or hard-to-reach localization of the node. At the same time, a needle no thinner than 16 G is required, and the length of the tissue core must be from 1.5 cm.
Why is it forbidden to split the obtained biopsy specimen between different laboratories?
This is strictly unacceptable, as it violates the integrity of the assessment of the macroscopic and microscopic picture. The pathologist must see the entire volume of tissue to accurately determine the growth type and cellular composition.
What else to study on this topic
- Molecular biological studies in lymphomas
- Genetic tests for the verification of neoplasms
- Immunohistochemical (IHC) markers of marginal zone lymphoma
- Technique of lymph node excisional biopsy
- Differential diagnosis of reactive lymphadenopathies
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