Basics of cytology

Abstract

This overview is intended to give a general outline about the basics of Cytopathology. This is a field that is gaining tremendous momentum all over the world due to its speed, accuracy and cost effectiveness. This review will include a brief description about the history of cytology from its inception followed by recent developments. Discussion about the different types of specimens, whether exfoliative or aspiration will be presented with explanation of its rule as a screening and diagnostic test. A brief description of the indications, utilization, sensitivity, specificity, cost effectiveness, speed and accuracy will be carried out. The role that cytopathology plays in early detection of cancer will be emphasized. The ability to provide all types of ancillary studies necessary to make specific diagnosis that will dictate treatment protocols will be demonstrated. A brief description of the general rules of cytomorphology differentiating benign from malignant will be presented. Emphasis on communication between clinicians and pathologist will be underscored. The limitations and potential problems in the form of false positive and false negative will be briefly discussed. Few representative examples will be shown. A brief description of the different techniques in performing fine needle aspirations will be presented. General recommendation for the safest methods and hints to enhance the sensitivity of different sample procurement will be given. It is hoped that this review will benefit all practicing clinicians that may face certain diagnostic challenges requiring the use of cytological material.

Keywords: Cytology; fine needle aspiration.

Figure 1

(a) Aspirate smear of an inguinal lymph node showing poorly formed granuloma with neutrophils. Combining the cytology and serological result, the diagnosis of cat scratch disease was made (Papanicolaou stain, ×400). (b) Bronchoalveolar lavage specimen with Strongyloides in an immunocompromised patient (Papanicolaou stain, ×600). (c) Scrape cytology smear of a non-healing ulcer on the hand of a patient with acute myeloid leukemia. The smear showed fungal hyphae characteristic of Mucor species (Hematoxylin and Eosin, ×400). (d) Bronchoalveolar lavage specimen showing the characteristic “fluffy” clusters of Pneumocystis jiroveci in a patients with AIDS (Papanicolaou stain, ×600).

Figure 2

(a) Low power view of aspirate smear of a solitary liver mass in a patient with chronic history of hepatitis C showing the development of hepatocellular carcinoma (Diff Quik stain, ×100). (b) High power view of metastatic small cell carcinoma to adrenal gland from the lung primary, diagnosis made through computed tomography-guided fine needle aspiration (FNA) (Diff Quik stain, ×600). (c) Pleural fluid cytology from a patient with ovarian adenocarcinoma showing the characteristic metastases (Papanicolaou stain, ×600). (d) Pleural fluid cytology from a patient with pleural-based mass diagnosed with mesothelioma. The diagnosis was confirmed by characteristic immunohistochemical stains on pleural fluid material (Papanicolaou stain, ×600).

Figure 3

Flow cytometry dot blot images from a submental lymph node. The panels on the left side are from the FNA material using the CRAT method and the panels on the right are from the same patient after the node was excised surgically. Both panels are identical demonstrating the efficiency of the “CRAT” method.

Figure 4

A case of Hodgkin's lymphoma that was diagnosed by FNA. (a and b) showing the cell block of this case that contains few Reed-Sternberg cells. The cells were immunoreactive for CD 15 (c) and CD 30 (d) and were negative for CD 45 and CD 20, confirming the diagnosis.

Figure 5

Diagram demonstrating the techniques we use to perform FNA. (a) we prefer to start with aspiration using a needle without syringe or suction (also known as the French technique or Zajdela technique). The advantage of this technique is providing a nice thin smear with less crush artifacts enabling the interpreter of optimum cytological morphology to proceed with appropriate triage. (b) the following passes can be used using a syringe with suction using negative pressure to increase cellularity. The aspiration can be done with or without commercially available “guns” depending on the aspirator preference (reprinted with permission from Al-Abbadi, Editor, Salivary Gland Cytology: A Color Atlas, Wiley-Blackwell 2011).

Figure 6

Diagram showing the steps that are used when aspirating a cystic mass. Re-aspiration of cystic lesions while keeping the needle of the first pass inside the mass is a very helpful trick that helps sample the wall of the lesion and believed to increase sensitivity (reprinted with permission from Al-Abbadi, Editor, Salivary Gland Cytology: A Color Atlas, Wiley-Blackwell 2011).