Accumulation of intracellular autofluorescent material or 'aging pigment' has been characterized as a normal aging event.
Lipofuscin is a common term for 'aging pigments'.
The word Lipofuscin is derived from the Latin word 'fuscus' = dark or sombre.
Lipofuscin is an insoluble lipid pigment and is also known as 'wear and tear pigment' as it is usually present in the cells of elderly persons.
It represents the accumulation of indigestible membrane material in lysosomes after autophagy.
Ingested material may accumulate when the rate of autophagy exceeds the capacity for digestion or when it has been chemically altered, as by lipid peroxidation, which would render it resistant to enzymatic degradation.
Ceroid is used to describe pathologically derived storage material, for example, in the neuronal ceroid lipofuscinoses.
Neuronal ceroid lipofuscinoses are a family of neurodegenerative diseases that are characterized by an accumulation of autofluorescent storage material (ceroid) in the lysosome, which has been termed 'lipofuscin-like'.
Lipofuscin the yellowish-brown granular pigment is usually found within atrophic parenchymal cells for example, in the hepatocytes, cardiocytes, and neurons.
Lipofuscins are autofluorescent and stain with the Sudan fat stains. They are Periodic acid-Schiff and Ziehl-Neelsen acid fast stain positive.
The affected organ containing large amounts of lipofuscin is deep brown in colour and is referred to as brown atrophy. Brown atrophy of heart is seen in senility and severe wasting.
Diagram showing Brown atrophy of Heart
The small muscle fibres contain brown pigment in the cytoplasm at each pole of their centrally-placed nuclei.
Diagram of cardiac muscle showing pigment at each pole of the nuclei
Lipofuscins are also found in the seminal vesicles.
Hermansky-Pudlak syndrome is a rare autosomal recessive disorder characterized principally by oculocutaneous albinism, a bleeding tendency, and a ceroid-lipofuscin lysosomal storage disease.
Lipofuscin occurs normally in perivenular hepatocyte lysosomes.
It is commonly noted in elderly patients.
It is increased in patients on various long term medications, such as phenacetin, chlorpromazine and various anticonvulsive drugs.
Ceroid pigment, a lipofuscin, may become more prominent in Kupffer cells following recent necrosis and increased deposits may follow intravenous infusion of fat emulsion.
Diagram of liver showing yellowish-brown pigment
Some authors have observed pigmented cytoplasmic granules, with the characteristic staining properties of lipofuscin (ceroid, 'wear-and-tear') pigment, in newborn human liver.
The pigment is found at the periphery of the lobule in hepatocytes and some bile ductular cells.
The bowel sometimes shows lipofuscin pigmentation.
The commonest example is melanosis coli, a symptomless condition in which the mucous membrane of the colon has a brown or black colour.
This is due presence of many macrophages laden with a brown pigment in the connective of the mucosa.
The pigment is a lipofuscin.
This condition is related to the habitual ingestion of anthraquinone purgatives.
It seems that these have a specific effect not only in increasing the number of macrophages in the bowel mucosa but also in increasing the lysomal activity within them.
The lipofuscin is derived from the lysosomes.
Diagram showing pigmentation of the bowel in melanosis coli (gross and microscopic).
Brown bowel syndrome is characterized by deposits of lipofuscin in the tunica muscularis of the small intestine.
Its etiology is associated with chronic malabsorption resulting in a deficiency of vitamin E.
Accumulation of lipofuscin is one of the most characteristic features of ageing observed in retinal pigment epithelial cells.
Study has shown that lipofuscin pigment may accumulate in retinal pigment epithelium cells and macrophages over several types of benign and malignant choroidal tumors.
The colour of the pigment, varies with the nature and color of the underlying lesion. On the surface of deeply pigmented tumours the lipofuscin pigment may produce an orange color, whereas over amelanotic lesions it may appear brown or reddish-brown.
Black or blue kidney may be due to deposition of lipofuscin pigment. Differential diagnosis -hemosiderin and melanin deposits.
Diagram of Blue Kidney
Lipofuscin appears to correlate directly with age, however, since such pigment can also accumulate rapidly with extensive tissue wasting it can be found in younger patients.
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