Pathology and Disease Diagnosis
4
Abstract
A methodical approach is a prerequisite for an accurate diagnosis and requires a description
of the tissue changes that occur following infectious and non-infectious conditions. Cells
have a limited repertoire of morphological response to injury which is linked to biochemical mechanisms that determine the outcome of cell damage, thus accounting for the
appearance of cells within lesions inducing general pathological changes, rather than
those that are pathognomonic. This chapter covers the different types of cell and tissue
responses to acute or chronic injury.
Keywords
Fish disease Inflammation Proliferation Circulatory disturbances Necrosis Pigments
Neoplasia
Pathology is the study and diagnosis of disease, and the
recognition and interpretation of the physiological and pathological processes. This requires a thorough understanding
of normal tissue structure and microanatomy. Normal structure varies widely among species, age and physiological
and developmental stages, and even within a population
variations may occur, therefore understanding these changes
and how they relate to the status of the species under investigation is essential. Furthermore, many diseases look similar at the gross level and to illustrate this aspect, images from
skin, kidney and liver showing a range of lesions of different
causes are presented in Figs. 4.1, 4.2 and 4.3.
Cell types in fish are, in principle, the same as those
found in mammals and similarly, many direct and indirect
pathological stimuli induce general pathological changes
rather than being pathognomonic. Cells have a limited
repertoire of morphological response to injury and are
linked to biochemical mechanisms that determine the outcome of cell injury, accounting for the appearance of cells
within lesions.
A methodical approach is a prerequisite for an accurate
diagnosis and this requires a description of the tissue changes
that occur in relation to infectious and non-infectious agents,
response to acute or chronic injuries, nutritional imbalance
and other causes of disease or abnormality, followed by
histopathology. The following areas will be covered in this
chapter: inflammation, proliferation, circulatory disturbances,
cell injury and necrosis, pigments and mineralization and
neoplasia. Finally, a brief description of artefacts is provided
to help distinguish these from tangible pathological changes.
Common prefixes and suffixes used in compounded words
are provided in Table 4.1, and a glossary appropriate to veterinary terminology is provided in Chap. 13. Reference should
also be made to Chap. 2 which discusses normal tissues.
4.1
Inflammation and Proliferation
Lesions can be classified according to their onset, namely
acute and chronic. However the pathogenesis of an inflammatory lesion and the histological appearance can be similar.
A major component of acute inflammation involves changes
in plasma proteins. Serous and fibrinous exudates are a
feature of inflamed tissues and histologically consist of
eosinophilic staining in the intercellular space and presence
of eosinophilic strands, respectively.
Inflammatory foci are characterized by exudation comprising a vascular response, vasodilatation, interstitial fluid
changes and cell migration, all of which are common in
D.W. Bruno et al., A Colour Atlas of Salmonid Diseases,
DOI 10.1007/978-94-007-2010-7_4, # Springer Science+Business Media B.V. 2013
33
4
Abstract
A methodical approach is a prerequisite for an accurate diagnosis and requires a description
of the tissue changes that occur following infectious and non-infectious conditions. Cells
have a limited repertoire of morphological response to injury which is linked to biochemical mechanisms that determine the outcome of cell damage, thus accounting for the
appearance of cells within lesions inducing general pathological changes, rather than
those that are pathognomonic. This chapter covers the different types of cell and tissue
responses to acute or chronic injury.
Keywords
Fish disease Inflammation Proliferation Circulatory disturbances Necrosis Pigments
Neoplasia
Pathology is the study and diagnosis of disease, and the
recognition and interpretation of the physiological and pathological processes. This requires a thorough understanding
of normal tissue structure and microanatomy. Normal structure varies widely among species, age and physiological
and developmental stages, and even within a population
variations may occur, therefore understanding these changes
and how they relate to the status of the species under investigation is essential. Furthermore, many diseases look similar at the gross level and to illustrate this aspect, images from
skin, kidney and liver showing a range of lesions of different
causes are presented in Figs. 4.1, 4.2 and 4.3.
Cell types in fish are, in principle, the same as those
found in mammals and similarly, many direct and indirect
pathological stimuli induce general pathological changes
rather than being pathognomonic. Cells have a limited
repertoire of morphological response to injury and are
linked to biochemical mechanisms that determine the outcome of cell injury, accounting for the appearance of cells
within lesions.
A methodical approach is a prerequisite for an accurate
diagnosis and this requires a description of the tissue changes
that occur in relation to infectious and non-infectious agents,
response to acute or chronic injuries, nutritional imbalance
and other causes of disease or abnormality, followed by
histopathology. The following areas will be covered in this
chapter: inflammation, proliferation, circulatory disturbances,
cell injury and necrosis, pigments and mineralization and
neoplasia. Finally, a brief description of artefacts is provided
to help distinguish these from tangible pathological changes.
Common prefixes and suffixes used in compounded words
are provided in Table 4.1, and a glossary appropriate to veterinary terminology is provided in Chap. 13. Reference should
also be made to Chap. 2 which discusses normal tissues.
4.1
Inflammation and Proliferation
Lesions can be classified according to their onset, namely
acute and chronic. However the pathogenesis of an inflammatory lesion and the histological appearance can be similar.
A major component of acute inflammation involves changes
in plasma proteins. Serous and fibrinous exudates are a
feature of inflamed tissues and histologically consist of
eosinophilic staining in the intercellular space and presence
of eosinophilic strands, respectively.
Inflammatory foci are characterized by exudation comprising a vascular response, vasodilatation, interstitial fluid
changes and cell migration, all of which are common in
D.W. Bruno et al., A Colour Atlas of Salmonid Diseases,
DOI 10.1007/978-94-007-2010-7_4, # Springer Science+Business Media B.V. 2013
33