Pigments and lipids Flashcards
what is perls staining used for and
detects the presence of iron
what is an artefact
deposits produced as result of a chemical reaction in tissue
define Endogenous
haematogenous or autogenous
produced within the tissue and have physiological function or are a by- product of normal metabolic process
define Exogenous
gain access to body accidentally with no physiological function. Usually minerals, enter by inhalation or implantation in skin during industrial exposure.
what are the artefact pigments ?
formalin
malarial
mercury
dichromate
what is formalin pigment and how is it removed
brown/black deposit following fixation in acid
formalin, especially seen in haemorrhagic tissue. Removed with picric acid
how is formalin pigment formed
Formalin pigment is formed from haemoglobin by the action of formaldehyde at acid pH (prevented by short fixations in neutral buffered formalin). In and around blood vessels
what is malarial pigment
similar to formalin pigment, formed in/near RBC’s
with parasite.
how is malarial pigment formed
Malarial pigment, brown/black pigment occurs in parasitic infection (such as Plasmodium malariae). In and around blood vessels. Left over from the metabolism of haemoglobin by the malarial parasite
what is mercury pigment
black deposit formed with fixatives containing
Mercury. Removed with iodine/hypo
how is mercury pigment formed
Mercury pigment can develop when mercuric chloride is incorporated into fixatives
What are dichromate deposits
yellow/brown deposits after potassium
dichromate fixation and insufficient washing prior to dehydration. Removed
with acid alcohol
how are dichromate deposits formed
Dichromate deposits can form after fixation with potassium dichromate containing fixatives and insufficient washing to remove any excess fixative
what are the three types of pigments and how do we differentiate between them
Endogenous - related to the cell as have physiological function (eg might always see them around the nucleus)
Artefact - non-related to cells so will be present everywhere
Exogenous- enter body via airways/skin
what is Lipofuscin
yellow-brown pigment granules composed of lipid-containing residues of lysosomal digestion. Aging or ‘wear-and-tear’ pigments
what are the two types of endogenous pigments
haematogenous and non- haematogenous
what are haematogenous pigments
haemoglobin:
globin - protein part
heme - pigment part:
splits off into iron or bile pigments
where are bile pigments found
liver/gall bladder/spleen etc
what do bile pigments do
Follows breakdown of RBC’s and release of haemoglobin and iron removal, leaving biliverdin. Transported to liver by phagocytic cells, reduced to bilirubin.
what is Haematoidin and where is it seen
an orange-yellow pigment in the bile that forms as a product of hemoglobin; excess amounts in the blood produce the yellow appearance observed in jaundice
Haematoidin seen in spleen haemorrhagic areas, sometimes brain
what are the three bile pigments and what type of pigment are they
biliverdin, bilirubin, haematoidin
endogenous
what does the bile - obstructive jaundice look like in histology and how is this caused (in general)
Accumulation of pigments – bile
Often this is due to extrahepatic biliary tract obstruction
Bile may also accumulate in liver (called cholestasis) when there is hepatocyte injury
what does an H&E stain of bile - obstructive jaundice look like (colour)
Orange pigment in bile ducts in portal areas liver in H&E. Higher magnification of area more impacted by obstruction of bile ducts
on a bile - infarction slide what would you see
lysed hepatocytes
what is Cholestasis
bile accumulation in the liver
facts on Lipofuscin and what type of pigment is it
Oxidation of lipids. Normal in ageing process, abnormal in Vit E deficiency. Seen in heart, liver, adrenal, testis, neurones. Stained by Sudan Black, PAS, Schmorl’s, Long Zn
endogenous
facts on melanin and what type of pigment is it
Intra cellular, brown/black. Normal in skin, retina, brain, hair shafts. Pathologically in benign naevus cell tumours, malignant melanoma Demonstrated by Masson Fontana (black)
endogenous
steps in the formation of melanoma (phases and key points)
- Benign Nevus - BRAF mutation
- Dysplastic Nevus - CDKN2A & PTEN loss
- Radial growth phase - CD1 increase, move from epidermis to dermis
- Vertical growth phase - E-cadherin loss
- Metastatic Melanoma - break basement membrane and move into cells, Distant metastases
what is a Nevus
birthmark or mole
what is iron stored as, where and in what state
Stored as haemosiderin in marrow and spleen in ferric (Fe+3) state