Interventional Cytopathology - An Overview

Introduction:

Cytopathology is the examination of individual cells. The external features of cells are studied with respect to their normal anatomical features. During biopsy studies a large tissue is collected and studied inorder to make a diagnosis. However, interventional cytology is carried out in large lesions. Samples are collected in small sections for cytopathological examination. Interventional cytology is carried out using two methods- Fine needle aspiration cytology (FNAC) and sediment cytology.

What Is Fine Needle Aspiration Cytology?

It is one of the most painless and rapid tests available. The sample is collected by aspirating the mass using a fine needle. It is used for palpable lesions (for example, lymph nodes, breast, and soft tissue masses) and non-palpable lesions (for example, abdominal and thoracic cavities). Fine needle aspiration can be performed with aspiration as well as without aspiration.

• With Aspiration: In this case, the sample is collected in a syringe with a plunger. The needle goes inside the mass, and the plunger is pulled up (negative pressure built). After this, move the plunger up and down to remove negative pressure. Now remove the needle from the mass. Separate the needle from the syringe with the plunger upward. This pushes the air inside the syringe. Again reinsert the needle into the syringe. Draw the collected sample onto the glass smear.

• Without Aspiration: In this case, we use only a syringe without a plunger. Insert the needle into the mass at varying angles. Withdraw the needle back. Now attach the needle to the syringe and draw the sample onto the glass smear with air pressure. This is used in vascular lesions and thyroid lesions. It is used to minimize bleeding.

Where Do We Use Fine Needle Aspiration Study?

• It is used in the detection of salivary gland tumors.

• It is used as an alternative to extensive surgical procedures for tissue examination.

• It is used to rule out swellings of the lymph nodes.

• Used as a follow-up procedure to check the extent of recurrence, if any.

• It is a detector of metastatic lesion of squamous cell carcinoma within cervical nodes.

What Are the Other Tests Carried Out Along With Fine Needle Aspiration Study?

Other tests helping out in the diagnosis and prognosis of cancer along with fine needle aspiration study are:

• X-Ray: This helps to rule the lesions of bone and chest.

• Ultrasonography (USG): It helps direct visualization of the needle into soft tissue and intra- abdominal mass.

• Computed Tomography (CT): This technique is used for lesions of the stomach and chest.

What Are the Advantages of Fine Needle Aspiration Study?

- It is a painless procedure.

- Minimally invasive and easy to carry out.

- Economically feasible.

- No anesthesia required.

- Outdoor procedure.

- Fast detection.

- Procedure can be repeated.

What Are the Contraindications of Interventional Cytology?

• Profuse bleeding hinders the sample collection.

• Pulmonary hypertension.

• Pancreatitis.

• Bacterial infection.

• Inflammation.

How Is Fixing a Sample Done?

This is the most important step in fixing a sample. One of the reasons for failure in fixation is the decomposition of tissue. Hence, it is advised to fix the sample following a surgical procedure immediately. The sample is fixed in 95 percent percent ethyl alcohol for 5 to 15 minutes. If hematoxylin and eosin stains are used, fixing them will take some more time. There are other external factors that affect the fixation process, such as:

• Buffer pH: The pH is adjusted at an appropriate level for the chemical reaction to take place. The pH should be maintained between six to eight.

• Osmolarity: The fixative should be used, which has more particles.

• Temperature: Increased temperature increases the fixation process.

• Penetration Capacity of Fixative: The thickness of the sample should be one to four millimeters. The diffusion of fixatives depends on the thickness of the tissue. A rapidly penetrating fixative should be used without causing damage to the tissue texture.

• Duration: The average time taken to fix a sample is twelve to twenty-four hours. Prolonged fixation can cause hardening and shrinkage of the tissue.

• Agitation: This increases the speed of penetration of fixative.

• Concentration: An optimum concentration of fixative gives the desired result in fixing a sample.

What Are the Materials Used in Fine Needle Aspiration Study?

• Twenty-three to twenty-seven gauge syringe.

• Fine-needle.

• Pistol-grip syringe holder.

• Cameco syringe holder.

• Franzen’s handle.

• Clean glass slide.

• Stains like pap stain and hematoxylin and eosin stain.

• Coplin jar for keeping ethyl alcohol.

What Is Sediment Cytology?

In sediment study, the obtained biopsy sample is fixed. The fixative is removed by centrifuging the sample. The sediment received from the centrifuge is prepared for further analysis.

What Are the Common Stains Used in Cytological Studies?

• Romanowsky Stain: Used in air-dried smears. It is superior to the Papanicolaou stain. Though for nuclear staining, Papanicolaou stain is ideal.

• Leishman Stain: Used in blood smears.

• May-Grunwald Giemsa (MGG) stain: Most commonly used in cytoplasmic staining.

• Jenner Stain: Helps stain darker and clearer nuclei (dark blue).

• Wright Stain: Used primarily in the diagnosis of ehrlichiosis.

How is the Specimen Adequacy Taken for Study Determined?

One such specimen adequacy is carried out by - "The Bethesda System (TBS)." This cytological study is basically done during Pap smear tests conducted in female cervix. The specimen is considered adequate if it has well-preserved squamous and endocervical cells. The minimum number of squamous cells checked for adequacy is conditional. For conventional smears, it should range from eight thousand to twelve thousand in number. And in liquid-based cytology, it should be within a range of five thousand cells.

How is the Pap Smear Interpreted?

In Normal conditions: The cells present in an epithelial layer are:- The outermost superficial layer consists of squamous cells with keratin, then the intermediate cells, which look like basophilic cells, then the parabasal cells, followed by innermost basal cells. These cells are arranged like a stratum, with the size of cells shrinking in descending order. But the size of the nucleus grows larger from the outer to the innermost layer.

• Superficial Squamous Cells: They appear eosinophilic polygonal with the centrally placed pyknotic nucleus. It is seen during the ovulatory phases of the menstrual cycle and the late proliferative stage. During this time, estrogen levels are high.

• Intermediate Squamous Cells: The nucleus is seen as bigger, vesicular, and evenly dispersed in granular chromatin. Cells are in a polygonal shape. Basophilic cytoplasm is seen. This is seen during the menstrual cycle's luteal and early follicular phases. Also seen during the second and third trimesters of pregnancy.

• Parabasal Squamous Cells: Round to oval-shaped smaller cells. Dense homogenous basophilic cytoplasm is seen. The nucleus is seen with finely granular chromatin. Seen in low estrogen patients (for example, premenstrual, postpartum and postmenopausal conditions).

• Basal Cells or Squamous Metaplastic Cells: Maximum deformity seen in this area. Round, polygonal cell with dense basophilic cytoplasm. Round and centrally located nuclei.

In Pathological Condition: During abnormal condition, like in cervical cancer the cells show squamous intraepithelial lesion.

• Human Papillomavirus (HPV): In cases of human papillomavirus (HPV) infection, the immature basal cells or damaged cells of the squamous cells are infected.

• Invasive Cervical Cancer: In invasive carcinoma of cervix, there is fungating or exophytic appearance of cells. The cells appear as ulcerative lesion and with infilterate mass.

• Squamous Cell Carcinoma (SCC) of the Cervix: The most common cancer of the cervix being the squamous cell carcinoma appears as solid nests with malignant cells showing keratinization or non-keratinization.

• Adenocarcinoma: In cases of adenocarcinoma the cells show glandular epithelium proliferation and mucin depleted cytoplasm.

Conclusion:

Interventional cytology is one of the provisional diagnostic procedure. The diagnosis is confirmed by a biopsy which is a definitive diagnostic procedure. Tests are done under the supervision of a cytopathologist. Proper collection of samples is required for a more accurate result. Highly skillful and qualified professionals are required to meet the desired result.