Page 42 - Concise Pathology for Exam Preparation ( PDFDrive )

1 Cell Injury and Cell Death 27

FIGURE 1.18. Bile pigment in a section from liver (H&E; 2003).

Localized: deposits in macrophages, fibroblasts, endothelial and alveolar cells
secondary to haemorrhage in tissues, eg, bruise, black eye, brown indura-
tion of lung and infarction.
Generalized: deposits in reticuloendothelial cells (liver, spleen, bone
marrow) or parenchymal organs (liver, pancreas, kidney, heart) second-
ary to haemolytic disorders, blood transfusions, parenteral iron therapy,
idiopathic haemosiderosis and Bantu disease.
(iii) Severe progressive iron overload leading to fibrosis and organ failure is called
haemochromatosis.
(d) Acid haematin (haemozoin)
(i) Haemoprotein-derived brown-black pigment seen in malaria.
(ii) Does not stain with Prussian blue (because iron is in ferric form).
(e) Bilirubin
(i) Major pigment found in bile (Fig. 1.18), stains with Gmelin reaction (oxidation
by concentrated nitric acid to red/blue-green products) and Stein’s technique
(oxidation by iodine to form a green biliverdin pigment).
(ii) Derived from haemoglobin but contains no iron.
(iii) Excess of this pigment in tissues causes jaundice.
2. Exogenous pigments
(a) Inhaled pigments: The most common inhaled pigment is carbon; others
include silica, iron and asbestos. Inhaled carbon is taken up by alveolar mac-
rophages and may settle in the lungs or may be carried by lymphatics to hilar
lymph nodes.
(b) Ingested pigments: Chronic ingestion of metals can cause the following
conditions:
(i) Argyria: Due to chronic ingestion of silver; causes brownish pigmentation of
skin, bowel and kidney.
(ii) Chronic lead poisoning: Blue pigmentation on teeth at gum line is a feature of
chronic lead poisoning.
(iii) Melanosis coli: Pigmentation of colon associated with prolonged ingestion of
cathartics.
(iv) Carotenaemia: Yellow-red discoloration of skin caused by ingestion of carrots.
(c) Injected pigments: These include India ink, cinnabar, carbon, etc., used in
tattooing.

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