University of Hail: Inflammation and Neoplasia in Cytology PDF

University of Hail faculty of medicine Department of Pathology Fundamental concepts of inflammation and neoplasia (Benign and malignant)  INFLAMMATORY CYTOLOGY The inflammation is classified as; 1. Neutrophilic/eosinophilic 2. Mixed 3. Macrophagic. Classification is based on...

University of Hail faculty of medicine Department of Pathology Fundamental concepts of inflammation and neoplasia (Benign and malignant)  INFLAMMATORY CYTOLOGY The inflammation is classified as; 1. Neutrophilic/eosinophilic 2. Mixed 3. Macrophagic. Classification is based on The relative proportions of the various inflammatory cells in the reaction. If neutrophils (or eosinophils) predominate (greater than 80% of the inflammatory cells present), the reaction is classified as neutrophilic Suppurative or eosinophilic. If neutrophils and mononuclear cells are present in approximately equal numbers (50% to 80% polymorphonuclear, the remaining cells mononuclear) then the response is termed mixed. When mononuclear cells predominate (greater than 50% of the inflammatory cells present) the reaction is classified as macrophagic (non suppurative, histiocytic).  Many inflammatory reactions can be even further subdivided on the basis of morphology of the various cell lines. The purpose of sub classification is to provide information regarding pathogenesis of the reaction and to aid in the identification of etiology. NEUTROPHILIC INFLAMMATION Neutrophilic inflammation has two subtypes: ✓Neutrophilic with nondegenerate neutrophils ✓Neutrophilic inflammation with degenerate neutrophils. Nondegenerate neutrophils are either morphologically similar to those of peripheral blood or exhibit nuclear hypersegmentation. Degenerate neutrophils have characteristic nuclear and cytoplasmic changes. Nuclear changes in degenerate neutrophils include hyalinization and selling of nuclei (an early stage of karyolysis), pyknosis, karyorrhexis, and karyolysis. Pyknotic nuclei are intensely stained and homogeneous without internal chromatin patterns. Karyorrhectic nuclei are generally pyknotic and have been fragmented into small pieces. Karyolysis is the process of spontaneous dissolution of the nucleus and is recognized as the streaming of nuclear chromatin away from the nucleus into the cytoplasm.  Karyolysis can only be recognized in intact cells. Cytoplasmic features of degeneration in neutrophils are generally more subtle than nuclear features. The cytoplasm becomes homogeneous, glassy and somewhat basophilic.  Neutrophilic inflammation with nondegenerate neutrophils is the result of severe irritation. In most cases, etiologic agents are not observed. Neutrophilic inflammation with degenerate neutrophils indicates that there is not only severe irritation but also that there is destruction of neutrophils. Of all the degenerative changes, nuclear hyalinization and swelling and karyolysis are the most significant because they indicate acute cell death. Acute cell death in neutrophils results for the effects of local toxins. The most common toxins are bacterial, and whenever karyolysis is present sepsis should be suspected even if bacteria are not seen.  MIXED AND MACROPHAGIC INFLAMMATION Like neutrophilic inflammation, mixed or macrophagic inflammatory reactions may also be sub classified based upon the morphology of their neutrophils. Interpretation of neutrophil degeneration in these instances is the same as for neutrophilic reactions. In general, however, mixed or macrophagic reactions imply less severe irritation than neutrophilic reactions and the neutrophils are usually either nondegenerate or only mildly degenerate. Of greater importance than neutrophil morphology in mixed and macrophagic inflammation is macrophage morphology  Typical microphages are large, round to oval cells (20–35 µm) with eccentric round to oval or irregular nuclei. Nuclei have a lacy or reticulate chromatin pattern. Cytoplasm is abundant, granular, and faintly eosinophilic. Cytoplasmic vacuoles are present and generally contain phagocytized material. Phagocytized material is in most cases indistinct cellular debris or RBCs; In some instances, specific etiologic agents may be observed.  Many mixed inflammatory responses also contain epithelioid cells, inflammatory giant cells, or both. Epithelioid cells are morphologically similar to typical macrophages except that their cytoplasm contains either no or only small vacuoles, and phagocytized material is absent. Inflammatory giant cells are large, multinucleated macrophages, which may contain phagocytized material or have cytoplasm resembling that of epithelioid cells. Nuclei are discrete, typical macrophage nuclei and may be located peripherally at the cell margin or aggregated centrally.  Whenever epithelioid and/or inflammatory cells are present, a mixed or macrophagic reaction can be further classified a pyogranulomatous or granulomatous, depending upon the prevalence of neutrophils. Whereas classification of a response as mixed or macrophagic suggests nothing specific regarding etiology and may be associated with resolving neutrophilic inflammation as well as with more traditional causes of low-grade irritation, Classification as pyogranulomatous or granulomatous suggests that a foreign body, mycotic, actinobacterial or mycobacterial etiology should be considered. Often, these etiologic agents can be demonstrated cytologically.  EOSINOPHILIC INFLAMMATION Inflammatory reactions characterized by noticeable numbers of eosinophils are generally the result of allergic phenomena and merit separate consideration. Causes include parasitic disease, mast cell tumors, asthma and systemic atopic responses. Eosinophils are rarely the principal cell seen; rather, they represent a prominent accompaniment of a neutrophilic, macrophagic or mixed inflammatory reaction. Eosinophils in these responses may be quite transient;  IMPORTANT CONSIDERATIONS IN THE CYTOLOGIC EVALUATION OF INFLAMMATION First, numbers of the various inflammatory components are always estimated, never counted. Uneven distribution of cells in cytologic specimens makes counting differentials unreliable. Second, inflammatory cytology should not be regarded primarily as an indicator of lesion duration but rather is best regarded as an indicator of the level of tissue irritation. Type of inflammation often provides significant help in identifying underlying etiology. Finally, inflammatory cytology also has utility in following the course of an inflammatory reaction or the response to therapy.  BENIGN TUMORS Definition Benign tumors are focal and limited proliferations of morphologically normal or nearly normal cells, except for their abnormal arrangement and quantity. Benign tumors may occur in any tissue or organ and are characterized by: Limited growth A connective tissue capsule The inability to either invade adjacent tissue or metastasize  Cytologic Features In general, the cells of benign epithelial tumors differ little from normal, although they may display evidence of proliferative activity in the form of mitotic figures. In general, the epithelial cells tend to adhere well to each other and form flat clusters of cells with clear cytoplasm and small nuclei, wherein cell borders are clearly recognized, resulting in the so-called honeycomb effect. Benign tumors of mesenchymal origin, such as tumors of fat (lipomas), smooth muscle (leiomyomas), or connective tissue (fibromas), can be sampled only by needle aspiration biopsies. In smears, the cell population resembles the normal cells of tissue of origin (i.e., fat cells, smooth muscle cells, or fibroblasts). As a warning, some malignant tumors of the same derivation may be composed of cells that differ little from their benign counterpart.  Some benign tumors, such as tumors of endocrine or nerve origin, may show significant abnormalities in the form of large, hyperchromatic, sometimes multiple nuclei that explain why the DNA pattern of such tumors may be abnormal. In the presence of such abnormal cells, the cytologic diagnosis of benign tumors may be very difficult. Benign tumors caused by human papillomaviruses, such as skin warts and condylomas of the genital tract or bladder, may show significant cell abnormalities that may mimic cancer to perfection.  Cells from a benign epithelial tumor. In this example from prostatic hyperplasia, there is a flat sheet of cells of nearly identical sizes. The cell borders among cells are recognizable as thin lines, giving the “honeycomb” effect.  MALIGNANT TUMORS (CANCERS) Definition Fully developed primary malignant tumors are characterized by several fundamental features that apply to all cancers: Autonomous proliferation of morphologically abnormal cells results in abnormal, often characteristic tissue patterns and leads to the formation of a visible or palpable swelling or tumor. Invasive growth involves growth of cancerous tissue beyond the boundaries of tissue of origin. The invasion may extend into adjacent tissues of the same organ and beyond. Formation of metastases involves growth of colonies of cancer cells in distant organs, which again can proliferate in an autonomous fashion.  For metastases to occur, the cancer cells must have the ability to enter either the lymphatic or blood vessels. Spread of cancer through lymphatics is known as lymphatic spread and leads to metastases to lymph nodes. Spread of cancer through blood vessels is known as hematogenous spread and may result in metastases to any organ in the body, whether adjacent to the tumor or distant. The terms recurrent cancer and recurrence indicate a relapse of a treated tumor. Classification Cancers originating from epithelial structures or glands are known as carcinomas, whereas cancers derived from tissues of middle embryonal layer origin (such as connective tissue, muscle, bone) are classified as sarcomas. Carcinomas and sarcomas may be further classified according to the type of tissue of origin, which is often reflected in the component cells. Carcinomas derived from squamous epithelium, or showing features of this epithelial type, are classified as squamous or epidermoid carcinomas. Carcinomas derived from gland-forming epithelium or forming glands are classified as adenocarcinomas. carcinomas that may combine the features of these two types of cancer and are, therefore, known as adenosquamous  Carcinomas of highly specialized organs may reflect the tissue of origin, for example, hepatoma, a tumor of liver cells. Sarcomas are also classified according to the tissue of origin, such as bone (osteosarcoma), muscle (myosarcoma), and connective tissue or fibroblasts (Fibrosarcoma). Tumors derived from highly specialized tissues may carry the name of the tissue of origin, for example, glial cells of the central nervous system (glioma) or pigment-forming cells, melanoblasts (melanomas). Tumors may show combinations of several tissue types (hamartomas and teratomas), or reflect certain common properties, such as production of hormones (endocrine tumors). In certain age groups, tumors that show similar morphologic characteristics (although not cells of origin) have been grouped together as small-cell malignant tumors of childhood.  MORPHOLOGIC CHARACTERISTICS OF CANCER CELLS Identification of cancer cells by a light microscopic examination is an accepted means of cancer diagnosis, with certain limitations. The limitations may occur under two sets of circumstances. 1. Benign, proliferative or reparative processes may occasionally mimic cancer 2. Cancer cells may not differ sufficiently from normal cells of the same origin for secure microscopic identification. Both of these sources of error are avoidable, to a certain extent, by experience and by knowledge of the clinical history.  Cancer cells, like normal cells, are composed of a nucleus and a cytoplasm. The nucleus contains DNA and is therefore responsible for the replication of the genetic material and other events governed by DNA. The cytoplasm of cancer cells contains all of the organelles necessary for energy production and other cell functions. The principal morphologic differences between benign cells and cancer cells is based on cell size and configuration, interrelationship of cells, cell membrane, characteristics of the nucleus, and mitotic activity.  Cell Size The size of cancer cells usually differs from normal cells of the same origin. However, physiologic variability in cell sizes also occurs in benign tissues. This is particularly evident in epithelial tissues, such as squamous epithelium, wherein component cells may undergo substantial size changes during normal maturation Cancer cells vary in size beyond the limits usually associated with physiologic variation. Extreme size changes may be occasionally recorded; very large, sometimes multinucleated giant cells and very small cancer cells may occur. More importantly, a population of cancer cells is rarely made up of cells of equal size. The cancer cells usually vary in size among themselves (anisocytosis)  These differences may be enhanced in air-dried smears stained with hematologic stains Cell size alone is not a sufficient criterion for the diagnosis of cancer in the absence of nuclear abnormalities.  Cell Configuration Unusual, abnormal cell shapes may be observed in cancer cells, especially in advanced cancer. Cancer cell configuration may mimic normal cells of the same origin Bizarre configuration of cells may also be observed in benign processes, particularly those associated with rapid proliferation of cells of either connective tissue or epithelial origin. Therefore, once again, nuclear and clinical features must be considered before rendering the diagnosis of cancer.  Cell Adhesiveness One of the principal traits of cancer cells is their poor adhesiveness to each other. Thus, in smears prepared from an aspirated sample of a malignant tumor, the abundant cancer cells may appear singly or in loosely structured aggregates, whereas this phenomenon cannot be fully appreciated in the corresponding histologic preparation. Also, a smear from the corresponding benign tissue will yield cells mainly arranged in tightly fitting, orderly clusters, wherein the cell borders can be often identified. There are some differences in the adhesiveness of cells of various tumor types. cancer cells of epithelial origin tend to form clusters and aggregates.  Poor adhesiveness is more evident in anaplastic, poorly differentiated tumors than in well differentiated tumors. Cells of most non epithelial tumors, particularly malignant lymphomas and sarcomas, rarely, if ever, form clusters and tend to remain single.  Cell Membranes When normal (diploid or euploid) cells are grown on hard surfaces, such as glass or plastic, they show contact inhibition, or stop growing when their borders contact each other. The cell migration stops once the cell membranes come in contact with each other in the state of confluent monolayer. Simultaneously, the undulations of the cell membranes cease, the mitotic rate drops precipitously, and the synthesis of DNA, RNA decrease sharply. Although contact inhibition can be manipulated by various experimental means, it generally characterizes benign cells in culture.  In contrast, cancer cells grown on glass or plastic surfaces do not show contact inhibition. Their growth does not stop when a confluent monolayer is formed and the cells form multilayered accumulations (piling up) Malignant cells are also capable of changing the direction of their movements more frequently than normal cells. Contact inhibition may be lifted when benign cells are transformed in vitro into malignant cells by viral or chemical agents. The precise mechanisms of the differences in the behavior of normal and cancer cells in vitro remain to be elucidated.  The Nucleus Nuclear abnormalities are the dominant morphologic feature of cancer cells that allow their recognition in microscopic preparations. The key changes observed are: Nuclear enlargement, particularly in reference to the area of the cytoplasm [altered nucleocytoplasmic (N/C) ratio] in favor of the nucleus Irregularity of the nuclear configuration and contour Altered nuclear texture; hyperchromasia and coarse granulation of chromatin.  Abnormalities of sex chromatin in females Changes in nuclear membrane Nucleolar abnormalities Abnormalities of cell cycle and mitoses Special features observed in some tumors  Size The size and, hence, the area of the nucleus in smear and other cytologic preparations depends on DNA content. In most, but not all, populations of malignant cells, nuclear enlargement is a common feature, often encompassing a large proportion of cancer cells. Because the cytoplasm of such cells is often of approximately normal size, the area of the nucleus is disproportionately enlarged, resulting in an increase of the nucleocytoplasmic (N/C) ratio. Because the increase in the nuclear size usually reflects an increase in the amount of DNA, in malignant tumors.  Irregularities of the Nuclear Configuration and Contour The configuration of the nuclei in normal cells usually follows the shape of the cytoplasm. Most nuclei, in benign spherical or polygonal epithelial cells, are spherical. In cells of columnar shape, the nuclei are usually oval. Nuclei of elongated epithelial cells, fibroblasts, or smooth muscle cells are often elongated and sometimes spindle-shaped. Nuclear configuration of highly specialized cells probably reflects highly specialized functions. Thus, the nuclei of macrophages may be kidney-shaped and those of polymorphonuclear leukocytes and megakaryocytes show lobulations.  The nuclei of all benign cells have a smooth nuclear contour. The configuration of the nuclei of cancer cells also generally follows the configuration of the cells. Thus, most spherical or polygonal cancer cells have approximately spherical or oval nuclei. Elongated or “spindly” cancer cells have elongated nuclei. However, these nuclei often show abnormalities of the nuclear contour, best observed in spherical or oval nuclei. These abnormalities may be subtle, in the form of small protrusions or notches, in the nuclear membrane that may be difficult to observe and may require a careful inspection of the target cells Less often, the nuclei may show fingerlike protrusions.  Nuclear Texture Hyperchromasia and Coarse Granulation of Chromatin Dark staining of interphase nuclei of cancer cells with appropriated dyes, such as hematoxylin or acetic orcein, is known as hyperchromasia. Hyperchromasia is usually associated with changes in configuration of nuclear chromatin, which shows coarse granulation and may be associated with a thickening of the nuclear membrane. By contrast, normal fixed and stained nuclei have a transparent nucleoplasm, with a fine network of filaments of constitutive chromatin, which forms small dense granules known as chromocenters.  In females, the sex chromatin body (Barr body), representing facultative chromatin, may be observed as a dense, semicircular structure attached to the nuclear membrane. Hyperchromasia and coarse granularity of chromatin may be absent in cancer cells. Numerous examples of invasive cancer of various organs have been observed wherein nuclei of cancer cells are enlarged but completely bland and transparent. In some of these cells, enlarged nucleoli can be observed. These abnormalities are most often observed in clusters of cells with generally abnormal configuration and are usually accompanied elsewhere by more conventional cancer cell abnormalities. Thus, the finding of cell clusters with large bland nuclei is, a priori, abnormal and should lead to further search for evidence of cancer. It must also be stressed that nuclear enlargement and hyperchromasia may occur in normal organs, such as the embryonal adrenal cortex and endocrine organs, for example, the acini of the thyroid gland.  References G. Kocjan Fine Needle Aspiration cytology Diagnostic principles and Dilemmas Koss Diagnostic Cytology and it is Histopathologic bases, 5Th edition Thank you for listening