Histopathology: Fundamentals of histology Flashcards
Describe the histological features of squamaous cell carcinoma
- Keratin production (cytokeratins: CK)
- Intercellular bridges (Parallel lines between cells)
List the main sites of origin of squamous cell carcinoma
- Skin
- Head and neck
- Oesophagus
- Anus
- Cervix
- Vagina
Describe the histological features of adenocarcinoma
- Mucin production
- Glands (a well-like arrangement of cells)
List the main sites of origin of adenocarcinoma
- Lung
- Breasts
- Stomach
- Colon
- Pancreas
Describe the histological features of malignant melanoma
- Nests of melanocytes (Atypicaate thel proliferation)
- Melanin (brown pigment) in malignant cells. (Fontana stain) positive.
What are the main site of origin of malignant melanoma
-Melanocytes of the skin
Describe the histological features of lymphoma
- CD45+ immunostain (Lymphocyte marker)
- Others depend on the type of lymphoma
- Lymphocytosis/ sheet of lymphocytes (Non-Hodgkins lymphoma)
- Reed sternberg cells (Hodgkins lymphoma)
- Coffee bean/cleft/ butt cells (Follicular lymphoma)
- Starry night appearance (Burkkit lymphoma)
What are the main site of origin of lymphoma
- Mainly lymph nodes
- Lymph ducts
- Spleen
- Thymus
- M.A.L.T
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(Any lymphoid tissue)
-Also tonsils
Describe the cytological features of neutrophils and state the type of inflammatory processes they are associated with.
- Multi-lobated nuclei
- Granules
- Neutrophils are associated with acute inflammation
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Memory aid: Nute means acute
Describe the cytological features of lymphocytes and plasma cells and state the type of inflammatory processes they are associated with.
- Similar appearance
- Large diffuse nuclei
- Very little cytoplasm
- Plasma cells have slightly greater cytoplasm
- Lymphocytes and plasma are both associated with chronic inflammation
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-LymphoCyte Chronic.
Describe the cytological features of eosinophils and state the type of inflammatory processes they are associated with.
- Bilobed nucleus
- Red granules
- Eosinophils are associated with allergic reactions, parasitic infections and some tumours (Hodgkins disease, eosinophils present but not tumour cells)
- eg eosiniphillic oesophagitis, food allergy “Asthma of the oesophagus”.
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- Eosiniphils - Ecsema - Allergy
- “Having an Allergy is not Easy”
Describe the cytological features of mast cells and state the type of inflammatory processes they are associated with.
- Large cells with diffuse nuclei
- Prominent granules (Contains inflammatory mediators)
- Mast cells are associated with some kind of allergic reaction
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Describe the cytological features of macrophages (/granulomas) and state the type of inflammatory processes they are associated with.
- Normal nucleus, lots of cytoplasm
- Cytoplasm is diffuse and quite granuley
- Macrophages are associated with late acute inflammation
- Associated with chronic inflammation in the form of granulomas.
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- Macrophages are (“Brainless cells that arrive at the end of the party to clear up the debree”).
- A granuloma is an organised collection of activated macrophages.
- Macrophages can be used to confirm that a sputum sample is a good sample, and not just spit.
- Granulomas associated with infections (TB), leprosy, fungal infections, idiopathic (sarcoid).
- The caseous necrosis in the lung associated with TB is an example of macrophages / granuloma.
Explain the difference between histochemical and immunohistochemical and give 3 examples of each
- Histochemical: agent added that causes a chemical reaction to specific components of a cell or a specific tissue, allowing them to be shown under microscope.
- Immunohistochemical: Antibodies, that recognise a specific antigen, is added to a tissue sample, with an agent subsequently added to detect and visualise the antibody.
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- Histochemical: Detects and visualises tissues based on certain chemical properties
- Immunohistochemical: The subsequent agent can either be a fluorescent antibody or another ‘detector’ system to make the antibodies visible [eg immunoperoxidase]
Give 3 clinical scenarios where histochemical stains are useful in diagnosis
- Prussian blue iron stain: shows haemochromatosis (eg iron overload in the liver).
- Congo red stain: +ve in amyloid in the gomerulus (Amyloid is protein that signifies some diseases eg AL amyloidosis/light chains).
- Fontana stain: shows melanin, indicates melanoma.
