Summary The prevalence, pattern of inheritance, and phenotype of Darier's disease was examined in a cross-sectional study of cases in north-east England. Lebert (1813–1878), a German pathologist, examined samples taken from effusions, tracheobronchial secretions, and urine (Figs. Later, cytological examinations were used to diagnose different tumoral diseases.

During his work in Berlin, Müller observed tumor cells in samples taken from tumoral tissue after surgical excision. The German physiologist and anatomist Johannes Müller (1801–1858) performed the first cytological examinations in 1838. Therefore, the use of a microscope for diagnostic purposes was delayed until the beginning of the nineteenth century.

The first cytological examinations were performed after the invention of the microscope, and this development has led to the discovery that “all living organisms are formed with cells.” However, many famous pathologists, such as the Italian Giovanni Baptista Morgagni (1682–1771), the British Matthew Baillie (1761–1823), and the French Marie François Xavier Bichat (1771–1802), rejected the use of microscope. In cytological examination, it is important to detect extracellular materials (mucin, hyaline material, keratin, collagen, foreign body, and artifacts), not only the cells.Ĭytology is a diagnostic method that is based on investigating the morphological changes that occur in cells during the course of diseases. Another characteristic that should be determined in cytological examination is the cellular patterns (granulomatous reaction, cellular atypia, panniculitis, rosette formation, and streptocytes). While bacteria, parasites, and fungi are seen in cytological examination, cytopathic effects of viruses are determined. Other cells are melanocytes, sebocytes, foamy cells, mast cells, and multinucleated giant cells.

The most common cells observed in cytological examination originate from keratinocytes (basaloid cell, acantholytic cell, tadpole cell, multinucleated giant keratinocyte, dyskeratotic cell, apoptotic cell, and koilocyte) or hematological cells (eosinophils, neutrophils, lymphocyte, erythrocyte, thrombocyte, plasma cell, and histiocyte). It is very important to distinguish all cells and extracellular structures observed in the cytological examination.

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