They propose that aged basal cells contain lipofuscin bodies that cannot be removed and might promote the aging of neighboring cells, generating a feedback loop that causes more and more neighbor cells to become aged and contain lipofuscins. Such cells might then aggregate into a spot with an irregular shape. They propose that the protrusion of a flat spot is a result of the death of aged cells in the spot and release of lipofuscin bodies. The aggregating cells would form a capsule, and the dense lipofuscin bodies make the protruding spot soft and dark in color. However, this proposal appeared as a preprint in 2015, has little direct empirical support, and has never been published in a peer reviewed journal. Another group has reported that "age spots" taken from human skin biopsies of patients facial senile lentigo of Fitzpatrick skin type III or IV aged 55–62 are enriched with senescent fibroblasts compared to surrounding skin. The dark coloration appeared to be due to higher melanin levels and activity of tyrosinase in the senescent fibroblasts than in the controls, potentially related to lower SDF1 expression. Patients were then administered six weekly treatments of microneedle fractional radiofrequency aimed at eliminating dermal senescent fibroblasts; this led to a marked decrease in epidermal pigmentation compared to baseline, accompanied by a decrease in the synthesis of collagen and the normalization of suppressed SDF1 expression. Treatment
Treatment for liver spots is almost never done for health-related reasons, though it is sometimes done for aesthetic ones.
A biopsy of the retina and choroid layer may be performed. In affected liver, biopsy shows focal areas of necrosis and sinusoidal widening. H&E staining show extracellular frothy pink material. Typical cysts with a solid dark dot can be seen using a Grocott silver stain. Differential diagnosis
Pneumocystosis may appear similar to pulmonary embolism or adult respiratory distress syndrome. Other infections can present similarly such as tuberculosis, Legionella, and severe flu. Prevention
There is no vaccine that prevents pneumocystosis. Trimethoprim/sulfamethoxazole (co-trimoxazole) might be prescribed for people at high risk. Treatment
Treatment is usually with co-trimoxazole. Other options include pentamidine, dapsone and atovaquone. Outcomes
It is fatal in 10-20% of people with HIV/AIDS. Pneumocystosis in people without HIV/AIDS is frequently diagnosed late and the death rate is therefore higher; 30-50%. Epidemiology
The exact number of people in the world affected is not known. Pneumocystosis affects lungs in around 97% of cases and is often fatal without treatment. History
The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War. It was then known as plasma cellular interstitial pneumonitis of the newborn.Pneumocystis jirovecii (previously called Pneumocystis carinii) is named for Otto Jírovec, who first described it in 1952. == References ==