The field of diagnostic pathology is concerned with the causal study of diseases. It addresses primarily four components of a disease- its cause, pathogenesis, morphological changes and clinical manifestations. The study of disease involves a study of varied disease markers using techniques that are specific to organs and tissue types. The fields of anatomical and clinical pathology are intrinsic to diagnostic pathology. Anatomical pathology involves a gross, chemical, immunologic and molecular examination of tissues, organs and whole bodies. It includes cytopathology, dermatopathology, neuropathology, renal pathology, etc. Clinical pathology employs various visual and microscopic tests to analyze the biophysical properties of tissue samples involving cultures and automated analyzers. Immunopathology, hematopathology and radiation pathology fall within the domain of clinical pathology. The aim of this book is to present researches that have transformed this discipline and aided its advancement. It covers in detail some existing theories and innovative practices of diagnostic pathology. It aims to equip students and experts with the advanced topics and upcoming concepts in this field.