2. Introduction – definition
Classification
Endogenous pigments
Artifact pigments
Exogenous pigments and minerals
Take home message
3. Pigments
Pigments are defined as substances occurring
in living matter that absorb visible light
May greatly differ in origin, chemical
constitution and biological significance.
They can be either organic or inorganic
6. Endogenous pigments
These substances are produced either within
tissues and serve a physiological function, or are
by-products of normal metabolic processes.
They can be further subdivided into:
a. hematogenous (blood-derived) pigments
b. non-hematogenous pigments
c. endogenous minerals
7. A) Hematogenous
This group contains the following blood-derived
pigments
hemosiderins
hemoglobin
bile pigments
porphyrins
8. Hemosiderin
Hemoglobin-derived, golden yellow to brown,
granular or crystalline pigment normally appear
intracellularly.
iron is in the form of ferric hydroxide that is bound
to a protein framework apoferritin, to form ferritin
micelles
Hemosiderin pigment represents aggregates of
ferritin micelles
9. Hemosiderin
Normal conditions - small
amounts in the
mononuclear phagocytes
of the bone marrow,
spleen, and liver,
Local or systemic
excesses of iron
hemosiderin accumulate
within cells.
10. Significance
Increased hemosiderin deposition seen in
Hemorrhage in tissues - organizing hematomas,
hemorrhagic infarcts, fractures
systemic overload of iron - hemosiderosis.
The main causes of hemosiderosis are
1. increased absorption of dietary iron due to an
inborn error of metabolism called
hemochromatosis
2. Hemolytic anemias,
3. Repeated blood transfusions
11. Localised Hemosiderin Deposits
Localized deposits in
dermatofibromas
Pulmonary
hemosiderosis: seen in
mitral stenosis & left
ventricular failure –
‘heart failure cells’.
12. Demonstration of hemosiderin
Perls’ Prussian blue reaction
Principle :
Detection of ferric Fe3+ iron in tissues. Strongly
bound iron as hemoglobin will not react.
Sections treated with acidic solution of potassium
ferrocyanide and ferric iron present unmasks as
ferric hydroxide reacts to form an insoluble bright
blue pigment ferric ferrocyanide known as prussian
blue
3 K4Fe(CN)6 + 4Fe3+ Fe4[Fe(CN)6]3 + 12K+
13. Perls’ Prussian blue reaction
Fixative : Alcohol/ 10%
neutral buffered
formalin. Avoid the use
of acid fixatives
Control : postmortem
lung tissue (heart failure
cells)
Sections - Works well on
all types of section
Results
Ferric iron - blue
Nuclei - red
14. Turnbull’s blue stain for ferrous Fe2+
iron (Tirmann Schmetzer’s)
Principle :
◦ The method is very similar to Perls' Prussian blue, but
uses potassium ferricyanide instead of ferrocyanide.
◦ The ferrous iron reacts with the potassium
ferricyanide to form ferrous ferricyanide blue
compound known as Turnbull's blue.
Results
Ferrous salts and ferric salts converted by treatment with
ammonium sulphide - Deep blue
Nuclei - Red
15. Other methods
Lillie’s method for ferric and ferrous iron
◦ Ferric iron dark Prussian blue
◦ Ferrous iron dark Turnbull’s blue
◦ Nuclei red
Hukill and Putt’s method for ferrous and ferric
iron
◦ Ferrous iron red
◦ Nuclei blue
16. Hemoglobin
Basic conjugated protein
Composed of a colorless protein, globin, and a red
pigmented component, heme.
Histochemical demonstration of the ferrous iron is
possible only if the close binding in the heme
molecules is cleaved
17. Hemoglobin
Need to demonstrate the pigment may arise in
1.casts in the lumen of renal tubules in cases of
hemoglobinuria
2.active glomerulonephritis
Methods of demonstration :
A. Demonstration of enzyme Hb peroxidase by
benzidine – nitroprusside method (carcinogenic)
18. Methods of demonstration
Hemoglobin
B. Leuco patent blue V
method for hemoglobin
◦ Results
Hemoglobin peroxidase
(RBCs and neutrophils) -
dark blue
Nuclei – red
C. Tinctorial methods
◦ the amido black
technique
◦ the kiton red-almond
green technique
19. Bile pigments
Bile pigments are both conjugated and unconjugated
bilirubin, biliverdin, and hematoidin
Excess of bile pigments,
bile duct obstruction
Abnormality of bilirubin biliverdin metabolism
(congenital enzyme disorders)
Extensive liver cell death/ degeneration
20. Bile pigments
Bile pigments appear as
yellow-brown globules.
Confused with lipofuscin.
(need to identify bile
pigments mainly in the
hp examination of the
liver)
21. Bile Pigments vs Lipofuscin
H/E : Both appear yellow-brown in H&E-stained
paraffin sections
lightly counterstained with a suitable Mayers
hematoxylin
Under polarized light Bile pigments are not
autofluorescent and fail to rotate the plane of
polarized light (monorefringent)
lipofuscin is autofluorescent
22. Demonstration :
A. Modified Fouchet technique-
Principle :
bilirubin converted to green coloured biliverdin in
an acidic medium.
This oxidation is accomplished by ferric chloride in
trichloroacetic acid medium (Fouchet reagent)
(freshly prepared)
Fixation - Any fixative appears suitable.
23. Results :
Bile pigments -
emerald to blue-
green
Muscle - yellow
Collagen - red
24. Bile pigments
B. Gmelin technique-
Treatment with concentrated nitric acid
changing colour spectrum: yellow-green-blue-
purple-red.
Less specificity and unreliable. Test should be
repeated at least three times before accepting
the result as negative.
25. Porphyrin pigments
Normally occur in tissues in only small amounts.
Precursors of the heme portion of hemoglobin
Appears as a dense dark brown pigment
In fresh frozen sections exhibits a brilliant red
fluorescence that rapidly fades with exposure to
ultraviolet light.
26. Porphyrin pigments
The pigment, when
seen in paraffin
sections and viewed
using polarized light,
appears bright red in
color with a
centrally located,
dark Maltese cross.
28. Non-hematogenous endogenous
pigments
This group contains the following:
melanins
lipofuscins
chromaffin
pseudomelanosis (melanosis coli)
Dubin-Johnson pigment
ceroid-type lipofuscins
Hamazaki-Weisenberg bodies
29. Melanin
Light brown to black
pigment
Normally found in skin,
eye, substantia nigra of
the brain, and hair
follicles
Pathological conditions -
found in benign nevus
cell tumors and
malignant melanomas.
30. Melanin
Tyrosine DOPA Intermediate pigment
Melanin
melanins are bound to proteins, and these
complexes are localized in the cytoplasm of
cells within so-called ‘melanin granules’
31. Methods of demonstration of
Melanin
The most reliable of these are:
1. Reducing methods such as the Masson-Fontana silver
technique and Schmorl’s ferric ferricyanide reduction
test.
2. Enzyme methods (e.g. DOPA reaction).
3. Solubility and bleaching characteristics.
4. Fluorescent methods.
5. Immunohistochemistry (melanin activation
antigens).
32. Melanin
1. Reducing methods for melanin
Melanin is a powerful reducing agent and this property is
used to demonstrate melanin in two ways:
A. The reduction of ammoniacal silver solutions to form
metallic silver without the use of an extraneous
reducer is known as the argentaffin reaction
Masson-Fontana method for melanin and churukian
ammoniacal silver method for argentaffin and
melanin
Melanin, argentaffin, chromaffin and lipofuscins
black
Nuclei - red
33. Melanin
B. Melanin will reduce ferricyanide to ferrocyanide
with the production of Prussian blue in the presence
of ferric salts (Schmorl reaction)
Melanin, argentaffin, chromaffin and lipofuscins –
dark blue
Nuclei - red
35. 2. Enzyme methods
Cells that are capable of producing melanin can be
demonstrated by the DOPA(dihydroxyphenylalanine)
method.
Enzyme tyrosinase localized within cells will oxidize
DOPA to form an insoluble brown-black pigment
DOPA oxidase(tyrosinase) – brown, nuclei - red
36. 3. Solubility and bleaching methods
Melanins are insoluble in most organic solvents (due
to tight bond with protein component)
Use of strong oxidizing agents, such as
permanganate, chlorate, chromic acid, peroxide,
and peracetic acid, bleach melanin
Method of choice :
Peracetic acid,
Treatment with 0.25% potassium permanganate
followed by 2% oxalic acid
37. 4. Formalin-induced fluorescence (FIF)
Aromatic amines such as 5-HT, dopamine,
epinephrine (adrenaline), norepinephrine
(noradrenaline), and histamine, when exposed to
formaldehyde, show a yellow primary fluorescence
Useful in amelanotic melanoma
38. 5. Immunohistochemistry
Ideally used are S100, HMB 45 and PGP 9.5
S100 protein antigen gold standard antibody remains
expressed in cells derived from the neural crest
(so not specific for melanocytes alone)
HMB 45 demonstrates melanosome formation and
melanocytic differentiation (Not a melanoma Ag)
39. Ochronosis
Melanin-like pigment, present in cartilages of
ear, larynx, trachea, joints etc.
Formed from homogentisic acid, in alkaptonuria.
40. Lipofuscins
Yellow to red-brown
pigments
produced by an
oxidation process of
lipids and lipoprotein
Hepatocytes, Cardiac
muscle cells, adrenal
cortex, Testis, ovary,
spinal cord, and
ganglia, edge of a
cerebral hemorrhage
or infarct, involuntary
muscle, cervix, and
kidney
41. Methods of demonstration
The most common and useful being:
Periodic acid-Schiff method
Schmorl’s ferric-ferricyanide reduction test
Long Ziehl-Neelsen method
Sudan black B method
Gomori’s aldehyde fuchsin technique
Masson-Fontana silver method
Basophilia, using methyl green
Churukian’s silver method
Lillie’s Nile blue sulfate method
43. Chromaffin
This pigment is normally found in the cells of the
adrenal medulla as dark brown, granular material.
It may occur in tumors of the adrenal medulla -
pheochromocytomas.
Demonstrated by Schmorl’s reaction, Lillie’s Nile blue
A, the Masson-Fontana, Churukian’s microwave
ammoniacal silver method, and the periodic acid-
Schiff (PAS) technique
44. Pseudomelanosis pigment
(melanosis coli)
Seen in macrophages in
the lamina propria of the
large intestine and
appendix
Endogenous lipopigment
Associated with purgative
use
Stains similar with those
of lipofuscin
45. Dubin-Johnson pigment
Found in liver of patients
with Dubin-Johnson
syndrome
histochemically similar to
lipofuscin
Presence of a brownish-
black, granular,
intracellular pigment
situated in the
centrilobular hepatocytes
46. Ceroid type lipofuscin
found in hepatic
cirrhosis
lipofuscin at an early
stage of oxidation.
47. Hamazaki-Weisenberg bodies
Small, yellow-brown,
spindle-shaped structures
found in the sinuses of LN
significance unknown.
present in patients of
sarcoidosis
Histochemically they are
similar to lipofuscin may
represent lysosomal
residual bodies
49. Calcium
Abnormal depositions of calcium found in
necrotic areas of tissue associated with
tuberculosis,
Infarction (Gandy-Gamna bodies),
atheroma in blood vessels,
malakoplakia of the bladder (Michaelis-Gutman
bodies)
53. Copper
Associated with Wilson’s
disease
Demonstrated by :
Rubeanic acid method
for copper
Modified rhodanine
technique
54. Uric acid and urates
Breakdown product of purine metabolism
Urate crystals give a negative birefringence under
polarizing microscope.
May lead to gout, characterised by,
i) subcutaneous nodular deposits of urate crystals,
ii) synovitis and arthritis
iii) renal disease and calculi
57. Artifact pigments
This group of pigments comprises:
formalin
malaria
schistosome
mercury
chromic oxide
starch
58. Formalin pigments
brown or brown-black deposit in tissues fixed in
acidic formalin.
The deposit is usually present in blood-rich tissues
such as spleen, hemorrhagic lesions, and large
blood vessels filled with blood
use of buffered neutral formalin will help to
minimizes the problem
59. Removal of formalin pigments
Treating unstained
tissue sections with
saturated alcoholic
picric acid
Treatment with 10%
ammonium hydroxide
in 70% alcohol for 5–15
minutes
60. Malarial pigment
Morphologically
similar to Formalin
pigment.
formed within RBCs
that contain malarial
parasite.
Removed by sat.
alcoholic picric acid.
Requires 12-24 hrs
treatment.
61. Schistosome pigment
This pigment is occasionally seen in tissue
sections where infestation with Schistosoma is
present.
Mercury Pigment
Brownish-black,extracellular crystal tissues that
have been fixed in mercury-containing fixatives.
Removed by treatment with Iodine soln
62. Chromic oxide
tissues that have been fixed in chromic acid or
dichromate-containing fixatives
Removed by treatment with 1% acid alcohol
Starch
This pigment is introduced by powder from the
gloves
PAS and GMS positive, when polarized, will
produce a Maltese cross configuration
64. Carbon
Commonly inhaled, ingested
or implanted in skin following
industrial exposure.
lungs and LNs of coal
workers- anthracosis
In skin tissues confused with
melanin deposition, but
treatment with bleaching
agents - carbon unaffected,
melanin - colour disappear.
65. Silica
causes disease silicosis
presents with
progressive
pulmonary fibrosis
histochemically inert,
but birefringent.
66. Asbestos
Asbestos: birefringent fibres
of magnesium silicate.
Collect in alveoli, at
periphery of lung.
Asbestos body-
beaded,yellow-brown,
barbell-shaped with
proteinaceous coat
containing hemeosiderin.
- demonstrated by prusian
blue reaction.
67. Tattoo pigments
found in the skin and
adjacent lymph node
of various colours of
the dye pigments
seen.
68. Others due to industrial exposure
Lead
Silver
Beryllium and aluminum
69. Take home message
Demonstration of pigments in tissues is an aid to
diagnosis
Pigments may present itself in tissue sections with
variety of morphology.
It is advisable to note a pigment’s morphology, tissue
site & relevant clinical data, to carry out various
special stains for confirmation
70. References
Bancroft’s Theory and Practice of Histological
Techniques 6th edition, 2008
Robbins and Cotran Pathologic Basis of Disease 9th
edition,
Handbook of Histopathological and Histochemical
Techniques, C. F. A. CULLING 3rd edition
Surgical Pathology- 12th ed.- Rosai & Ackerman