There are comparatively few diseases where carbohydrates are present in excess in the cells. The glycogen storage diseases would be one group. The photomicrograph shows a liver biopsy with an infant with galactosaemia. Despite the enzyme deficiency being present in a carbohydrate metabolism pathway, the hepatocytes show fatty change. Pigments Pigments are coloured substances that are found in the tissues of the body.
Endogenous pigments can be the product of either normal or abnormal metabolism.
Many examples are present in both groups. The following are examples of some of the most frequently encountered pigments. The paper section on the left is of a slice through a whole lung from a coal miner and shows severe pneumoconiosis. Black carbon deposits outline all of air spaces and, around and below the hilum, there are areas of densely pigmented black fibrosis known as massive pulmonary fibrosis. The skin specimen on the right shows a tattoo of a snake under attack from an eagle.