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Download The Pap Smear: Technique and Interpretation
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Definition of cytopathology Cytopathology is the study of normal and abnormal exfoliated cells in tissue fluid. The individual cells reflect the normal and abnormal morphology of the tissue from which they are derived. Types of exfoliated cyto-pathology Natural spontaneous exfoliation Natural covering epithelium: skin, urinary tract, vagina, and cervix. Glandular epithelial secretion: Breast (Nipple secretion). Sputum Urine Exudates and transudate: Pleural fluid Peritoneal fluid Pericardial fluid Joint fluid CSF Artificial enhanced exfoliation: Scrapings from cervix, vagina, oral cavity, and skin Brushing and lavage: bronchi, GIT, and urinary tract Fine needle aspiration (FNA) for: Body cavity fluid: pleural, pericardial & peritoneal fluids Cysts: neck, breast & ovary Solid tissue: body organs, tumors & other swell Role of cytopathology Early detection of unsuspected diseases (malignant or pre-malignant lesions). Confirmation of suspected diseases without surgical trauma. Diagnosis of hormonal imbalance. Useful in flow up the course of disease or monitoring therapy. Advantage of Cytopathology Rapid diagnosis - Inexpensive - Simple It is better in evaluating the infectious diseases. Supplement or replace frozen section or biopsy No injury to tissue allowing repeated sampling It is better for hormonal assay Cytopathological smear cover a wider surface than that involved in surgical biopsy. Disadvantage of Cytopathology Interpretation of the morphological cellular changes is based only on individual cell observation. Not always finally diagnosis, so it is confirmed by histopathology in some cases. Not determine the size and type of lesion of some cases. Factors that determine the appearance of cells Type of the technique used. Level of cell maturation at the time of cell collection. Nature of the parents tissue: soft tissue, cyst, or solid organ. Medium of the exfoliated cells. Interval between the stain of the exfoliated cells and collection of samples. Type of fixative, stain, and processing of the technique used. PAP smear: named after Dr. George Papanicolaou (1883-1962) Vaginal smears from guinea pigs (1917) Women (1920) Hormonal cycles Pathological conditions (1928) Normal Cervix Taking the Sample Liquid Based Cytology – lab processing The Pap Smear Cytologic screening for cervical cancer Cervical cancer screening has decreased morbidity and mortality Deaths from cervical cancer decreased from 26,000 to less than 5,000 between 1941 and 1997 Pap smears are not perfect For a high grade lesion, the sensitivity of a single pap smear is only 60-80% Estimated false negative rate is 30-50% Requires adequate specimen collection Requires adequate cytological review Requires adequate patient and physician follow-up 10% of women with cervical cancer had inappropriate follow-up. Requires access to care 50% of women with cervical cancer were never screened and 10% had not been screened within 5 years of diagnosis. Who to screen Any woman with a cervix who has ever had sexual activity. When to screen Start within 3 years of onset of sexual activity or by age of 21, whichever is first. Risk factors for cervical dysplasia Early onset of sexual activity Multiple sexual partners Tobacco Oral contraceptives Screening frequency Yearly until three consecutive normal pap smears, then may decrease frequency to every three years Annual screening for high-risk women is highly recommend. When to stop routine screening Age 65 and “adequate recent screening” Three consecutive normal pap smears No abnormal pap smears in last 10 years No history of cervical or uterine cancer Hysterectomy for benign disease Hysterectomy for invasive cervical cancer Cervical histology Original Squamous Epithelium Vagina and outer ectocervix 4 cell layers Well-glycogenated (pink) unless atrophic Columnar Epithelium Upper and middle endo-cervical canal Single layer of columnar cells arranged in folds Mucin producing (not true glands) Squamous Metaplasia Central ectocervix and proximal endocervical canal Replacement of columnar cells by squamous epithelium Progressive and stimulated by Acidic environment with onset of puberty Estrogen causing eversion of endocervix Transformation Zone Zone between original squamo-columnar junction and the “new” squamo-columnar junction Nabothian cysts visually identify the transformation zone if present Original Squamo-columnar Junction Placement determined between 18-20 weeks gestation Most often found on ectocervix Can be found in vagina or vaginal fornices Less apparent over time with maturation of epithelium “New” Squamo-columnar Junction Border between squamous epithelium and columnar epithelium Found on ecto-cervix or in endo-cervical canal Majority of cervical cancers and precursor lesions arise in immature squamous metaplasia, i.e. the leading edge of the squamo-columnar junction Squamous Epithelium Parabasal Cells Intermediate Cells Superficial Cells Endocervix Endocervical Cells Endometrial Cells Non-Epithelial Cells Lymphocytes Polymorphs sperms Normal smear Ectropion / Erosion At puberty & pregnancy the endocervical cells are pushed out to lie on the ectocervix Normal Ectropion Wide Ectropion Metaplasia The endocervical cells are transformed into squamous cells through the process of squamous metaplasia Metaplastic Cells
