Page 57 - Textbook of Pathology, 6th Edition

41 CHAPTER 3

Figure 3.19 Compound naevus showing clusters of benign naevus cells in the dermis as well as in lower epidermis. These cells contain
coarse, granular, brown-black melanin pigment. Cell Injury and Cellular Adaptations

melanin-like and is deposited both intracellularly and Accordingly, the effects of haemosiderin excess are as
intercellularly and is termed ochronosis, first described by under (Fig. 3.21 ):
Virchow. Most commonly affected tissues are the cartilages, a) Localised haemosiderosis. This develops whenever there
capsules of joints, ligaments and tendons. is haemorrhage into the tissues. With lysis of red cells,

DUBIN-JOHNSON SYNDROME. Hepatocytes in patients haemoglobin is liberated which is taken up by macrophages
of Dubin-Johnson syndrome, an autosomal recessive form where it is degraded and stored as haemosiderin. A few
of hereditary conjugated hyperbilirubinaemia, contain examples are as under :
melain-like pigment in the cytoplasm (Chapter 21). The changing colours of a bruise or a black eye are caused
by the pigments like biliverdin and bilirubin which are
Haemoprotein-derived Pigments formed during transformation of haemoglobin into
haemosiderin.
Haemoproteins are the most important endogenous Brown induration in the lungs as a result of small haemor-
pigments derived from haemoglobin, cytochromes and their rhages as occur in mitral stenosis and left ventricular failure.
break-down products. For an understanding of disorders of Microscopy reveals the presence of ‘heart failure cells’ which
haemoproteins, it is essential to have knowledge of normal are haemosiderin-laden alveolar macrophages.
iron metabolism and its transport which is described in
Chapter 12. In disordered iron metabolism and transport, b) Generalised (Systemic or Diffuse) haemosiderosis.
haemoprotein-derived pigments accumulate in the body. Systemic overload with iron may result in generalised
These pigments are haemosiderin, acid haematin haemosiderosis. There can be two types of patterns:
(haemozoin), bilirubin, and porphyrins.

1. HAEMOSIDERIN. Iron is stored in the tissues in 2 forms:
Ferritin, which is iron complexed to apoferritin and can
be identified by electron microscopy.
Haemosiderin, which is formed by aggregates of ferritin
and is identifiable by light microscopy as golden-yellow to
brown, granular pigment, especially within the mononuclear
phagocytes of the bone marrow, spleen and liver where
break-down of senescent red cells takes place. Haemosiderin
is ferric iron that can be demonstrated by Perl’s stain that
produces Prussian blue reaction. In this reaction, colourless
potassium ferrocyanide reacts with ferric ions of
haemosiderin to form deep blue ferric-ferrocyanide (Fig. 3.20).
Excessive storage of haemosiderin occurs in situations
when there is increased break-down of red cells, or systemic
overload of iron due to primary (idiopathic, hereditary)
haemochromatosis, and secondary (acquired) causes such as
in thalassaemia, sideroblastic anaemia, alcoholic cirrhosis, Figure 3.20 Haemosiderin pigment in the cytoplasm of hepatocytes
multiple blood transfusions etc. seen as Prussian blue granules.