What is a pathological biopsy?

Biopsy, short for “biopsy”, also known as surgical pathological examination, abbreviated as “external examination”; refers to the technique of removing diseased tissue from a patient’s body through excision, clamping, or puncture for pathological examination, as required for diagnosis and treatment.

It is the most important part of diagnostic pathology, capable of providing a definitive histopathological diagnosis for the vast majority of submitted cases, and is considered the final clinical diagnosis.

Basic Information

● Chinese Name:Biopsy

●Foreign Name:biopsy

●Full Name:Biopsy

●Function:Diagnosing conditions

Purpose of Biopsy

(1) To assist clinicians in making a diagnosis of a lesion or to provide clues for disease diagnosis.

(2) To understand the nature and development trend of the lesion, and to judge the prognosis of the disease.

(3) To verify and observe the efficacy of drugs, providing reference for clinical medication.

(4) To participate in clinical research, discover new diseases or new types, and provide histopathological basis for clinical research.

Application Scope

(1) Organs and tissues surgically removed, such as appendix, thyroid, gallbladder, lymph nodes, etc.

(2) Tissues obtained by puncture, such as liver, kidney, and lymph node puncture tissues.

(3) Small pieces of tissue excised from the lesion site, including tissues obtained via endoscopes such as fiber gastroscope and fiber bronchoscope.

Sampling

(1) The anatomical location, color, volume, texture of the specimen, presence of masses, i.e., whether the mass has a capsule; whether the capsule is intact; morphological changes of attached tissues such as skin, lymph nodes, etc.

(2) Specimens that can be sectioned should be cut open to observe the color and texture of the cut surface, presence of hemorrhage, necrosis, nodules, cystic cavities, contents within the cavities, and the nature of the contents.

(3) The length of organs such as the esophagus and appendix should be measured, and the color of the serosa and mucosa, presence of adhesions, etc., should be observed.

Precautions

(1) The sampling site should be accurate, avoiding necrotic tissue or obvious secondary infection areas. Sampling should be done at the junction between the lesion and normal tissue, aiming to obtain the lesion tissue along with a small amount of surrounding normal tissue. The size is generally recommended to be about 1.5cm × 1.5cm × 0.2cm.

(2) Sampling should have a certain depth, requiring vertical cutting parallel to the depth of the lesion. Gastric mucosal biopsies should include the muscularis mucosa.

(3) For hollow specimens, all layers of the wall should be sampled; for specimens with capsules, sampling should be done as much as possible; accessory tissues such as lymph nodes should all be sampled for microscopic observation.

(4) Avoid squeezing during excision or clamping of tissue, and avoid using toothed forceps to prevent tissue deformation that could affect diagnosis.

(5) Biopsy specimens with a diameter less than 0.5cm must be wrapped in transparent paper or gauze to prevent loss.

(6) Bone-containing tissues should first undergo decalcification before sampling.

Submission for Examination

(1) To prevent autolysis and decay of the tissue, specimens should be fixed promptly after sampling. The best fixative is 10% formaldehyde (formalin), and the volume of fixative should be more than 5 times the volume of the submitted specimen.

(2) The container for the specimen should be sufficiently large to maintain the original shape of the specimen, with a wide opening for easy placement and removal. The container should be labeled with: patient’s name, gender, specimen name, hospital number, bed number, etc. When submitting multiple specimens, be careful not to mix them up.

(3) Fill out the pathology submission request form carefully and completely as required.

Diagnostic Process

The histopathological diagnostic process of a biopsy generally involves: gross examination of the submitted specimen → sampling → (fixation, embedding) → preparation of thin sections → Hematoxylin and Eosin (HE) staining → observation under a light microscope. By analyzing and identifying the morphology of the diseased tissue and cells, combined with gross observation and relevant clinical data, diagnoses of various diseases are made. However, for some difficult and rare cases, additional auxiliary diagnostic techniques such as histochemistry, immunohistochemistry, electron microscopy, or molecular biology may be required based on the routine examination.

Biopsy Classification

1. By sampling method: Open biopsy (surgery), endoscopic biopsy (biopsy forceps), percutaneous needle biopsy (biopsy needle);

2. By sampling site: Soft tissue needle biopsy, bone tissue needle biopsy;

3. By sample type: Cytological biopsy, histological biopsy.

Clinical Biopsy

Preoperative Biopsy

Refers to a biopsy performed before therapeutic surgery or other treatments (such as radiotherapy, chemotherapy). Typically, a small portion of the lesion tissue is taken (often the entire lesion if it is small and superficial) and sent for pathological biopsy. It is fixed in formaldehyde, embedded in paraffin, sectioned, and HE stained, requiring 3-7 days for the diagnostic report. The purpose is to obtain a clear diagnosis so that clinicians can schedule appropriate surgical or other treatments accordingly. Such biopsies are mostly performed on an outpatient basis and involve taking only a small piece of tissue, hence also called “small biopsy” or “outpatient small specimen.” Materials obtained via endoscopy from internal organs are typical ultra-small biopsies, such as gastric mucosal lesions taken via gastroscopy or lung lesions taken via fiber bronchoscopy, to confirm whether it is cancer before proceeding with surgery or other treatments.

The advantage of this preoperative biopsy is minimal trauma, generally performable on an outpatient basis, and it helps confirm the diagnosis in the vast majority of cases, providing clinicians with a solid basis for formulating the next treatment plan. Its disadvantages are: difficulty in sampling deep-seated lesions; caution is needed for lesions that may cause bleeding or dissemination; non-standard sampling or failure to obtain the lesion can lead to diagnostic difficulties or missed diagnoses; patients and clinicians have to wait a relatively long time (over 3 days) for the diagnostic report, which is not suitable for those urgently needing a definitive diagnosis.

Intraoperative Biopsy

Refers to a biopsy performed during therapeutic or exploratory surgery, usually completed within 20-30 minutes to guide the surgical procedure. The most commonly used technique is rapid frozen sectioning, where fresh, unfixed specimens are rapidly frozen to below -18°C, sectioned, HE stained, and observed for diagnosis. Hence, it is also called “intraoperative frozen,” “rapid frozen,” or “frozen section.” Sometimes rapid paraffin sectioning or cytological examination techniques may also be used.

The purposes of intraoperative biopsy are:

① To determine the nature of the lesion to decide the surgical plan. For example, for a lesion of unknown nature, tissue is taken during surgery and sent for examination. After waiting 20-30 minutes, if the frozen section diagnosis is inflammatory or benign tumor, the surgical scope can be minimal; if malignant, an expanded radical resection is immediately performed.

② To understand the growth and spread of the lesion, especially malignant tumors, such as the extent and depth of invasion, presence of lymph node metastasis, and whether tumor cells are present at the surgical resection margins, to determine the surgical scope.

③ To confirm whether the obtained specimen contains the intended organ or lesion. For example, when removing the parathyroid gland but unable to distinguish it clearly in the surgical field, frozen biopsy can help confirm.

The greatest advantage of intraoperative biopsy is that it can provide a definitive diagnosis for lesions of unknown nature during surgery, allowing clinicians to immediately determine the surgical treatment plan and avoid a second therapeutic surgery. It achieves the goal in one procedure, sparing the patient a second surgery and saving medical staff from the labor of another operation. Secondly, it acts like a hundred-fold magnifying glass for the surgeon, revealing how deep and far the lesion has invaded and whether there are tumor cells at the resection margins.Its disadvantages are,

Rapid frozen sectioning has significant limitations:

① Not all biopsy materials are suitable for rapid frozen examination. It is only applicable for superficial organs (e.g., breast, thyroid) or internal organ surgical exploration when it is necessary to clarify benign or malignant nature. It is not suitable for diseases with complex lesions or tumors requiring identification of fine cellular structures (e.g., lymphoma). ② Due to sampling limitations, false negatives (missed diagnoses) are common.

③ Due to short preparation and staining times, thick sections, and less clear tissue and cell structure compared to routine paraffin sections, and the need to complete observation, analysis, and diagnosis within minutes without much time for contemplation or literature review, the diagnostic difficulty is high, often requiring experienced pathologists.

④ Due to the above reasons, and its accuracy rate is only about 90%, with high rates of inconclusive diagnoses and false negatives, and false positives can also occur. Therefore, rapid frozen biopsy is only an emergency preliminary qualitative diagnosis. Afterwards, the frozen biopsy material still needs to be processed into routine paraffin sections for pathological examination to obtain the final diagnosis. If there is a missed or misdiagnosed intraoperative frozen biopsy, a second surgery or other remedial measures may be required.

Postoperative Biopsy

Refers to a comprehensive pathological examination of the lesion and related tissues and organs removed during therapeutic surgery. Unlike preoperative biopsy, what is submitted for examination is often the entire lesion along with involved or expanded resection tissues and organs, as well as associated lymph nodes (e.g., in radical surgery for malignant tumors). Therefore, each lesion and submitted specimen must be sampled at multiple sites according to standards, routinely fixed in formaldehyde, embedded in paraffin, HE stained. When making a pathological diagnosis, not only the disease name and nature are determined, but also classification, extent of invasion, presence of dissemination, presence of lesions at surgical margins, etc., are provided as much as possible. It takes 3-7 days to issue the diagnostic report. Since this examination is mostly performed on hospitalized patients undergoing elective surgery, it is often called “large biopsy” or “inpatient large specimen.”

The purpose of postoperative biopsy:

is to determine the nature, type, severity of the disease, whether the resection is complete, and whether there is dissemination, to assess the correctness of preoperative or intraoperative diagnosis, the completeness of surgical treatment, the need for further adjuvant therapy, and prognosis orientation.

The advantage of postoperative biopsy is its comprehensive and meticulous examination, providing more reliable diagnosis and offering more information and basis for disease treatment and prognosis assessment. Its limitation is that it cannot provide a comprehensive diagnosis for diseases unsuitable for surgical treatment or found to be unresectable during surgery. Despite relevant standards and comprehensive sampling, due to subjective and objective limitations, there is still about a 1% rate of missed or misdiagnosed cases.

Cervical Biopsy

(1) It is best not to perform it one week before menstruation or during menstruation to prevent bleeding.

(2) A vaginal discharge examination should be done preoperatively to confirm no vaginitis before proceeding with the biopsy.

(3) The biopsy site may bleed, so avoid sexual intercourse, vaginal douching, or sitting baths for 1-2 weeks after the procedure. If vaginal bleeding is excessive, seek medical examination and treatment.

(4) If colposcopy equipment is available, the biopsy can be performed under colposcopy to improve diagnostic accuracy.