Leukemia (Blood Cancer)

            

            Sarcoidosis,  Sarcoid refers to the flesh and osis means disorder and the reason we call it that. Sarcoidosis is an immunologic disorder that results in lots of small nodules forming throughout the body the disease is actually poorly understood but we know that it's most common among African-American females normally the trusty cells of the immune system are ready to spot and destroy any foreign pathogens that could cause the body harm to help with this mission there's a certain category of cells in the body called antigen-presenting cells and these include macrophages b cells and dendritic cells the most common member of the antigen-presenting cell club is the dendritic cell which is named after its long beautiful branch-like arms called dendrites.

When a dendritic cell comes into contact with a pathogen it latches onto it and with its dendrites, it pulls it in and engulfs it the pathogen is then broken down and the dendritic cell then presents a piece of it calls an antigen on something called a major histocompatibility complex class ii molecule or MHC CLASS II for short. The dendritic cell then carries the antigen to the lymph node to find some naive helper t cells which are t cells that have never seen an antigen before eventually, it runs into a naive helper t cell, with a t cell receptor that recognizes and binds to the antigen then cytokines get released by the dendritic cell and this helps to activate the helper t cell which then begins to divide or proliferate the new t cells then leave the comfort of their lymph node to fulfill their destiny in the great fight against infection.

This brave t cells start secreting pro-inflammatory cytokines or signaling molecules and they then recruit more immune cells like additional t cells and macrophages, in Sarcoidosis though this process unfolds over and over throughout the body without the presence of a specific pathogen that the body's trying to destroy. In other words, the immune system seems to be going a bit haywire in the absence of a pathogen now the precise trigger isn't actually known but there are some known genetic and environmental risk factors. Genetic risk factors include being African-American and having a family member with Sarcoidosis, environmental risk factors include a prior infection with mycobacterium tuberculosis and Borrelia Burgdorferi, but to be specific these pathogens are long gone when the autoimmune problem sets in so when Sarcoidosis has triggered t cells and macrophages get attracted to a particular spot of healthy tissue now Sarcoidosis can involve nearly every organ but they most often involve hyalure lymph nodes which are the lymph nodes that are near the point where the bronchi meet the lung as more and more immune cells gather a particular spot they form small nodules called granulomas.

These granulomas have t cells at the periphery and macrophages at the center the granulomas in Sarcoidosis are non-caseating which means that there's no tissue necrosis at the center of the granuloma unlike some other granulomatous diseases like tuberculosis often macrophages fuse together to form a single large multi-nucleated cell called a langense giant cell, within the langense giant cell there are cytoplasmic inclusions called shorman bodies which are made of calcium and protein deposits, there are also things called asteroid bodies which look like tiny stars what they're made of are controversial, some scientists think that they're pieces of the cytoskeleton while others think that they're made up of lipids over time the granulomas cause lymph nodes to enlarge and that can cause bilateral Hilo lymphadenopathy, Sarcoidosis is a systemic disease meaning that the granulomas can sometimes form in other organs besides the lymph nodes.

Skin nodules are called erythema nordosum and typically develop on the lower legs along the tibias, these nodules are caused by inflammation of the fat within the skin layer and they're typically red hard and painful Sarcoidosis can also cause uveitis which is inflammation in the pigmented layer of the eye beneath the cornea and sclera, it can also take effect in the heart leading to problems like arrhythmias, Sarcoidosis can cause a variety of generalized symptoms like fever, weight loss, and fatigue, but in addition, there can be specific symptoms depending on which part of the body is most affected, these range from shortness of breath and coughing to tender leg nodules to vision changes, a diagnosis of Sarcoidosis usually involves a chest x-ray or ct scan of the chest to look for bilateral hilar-lymphadenopathy, in blood tests individuals typically also have an increased level of calcium which is caused by excess vitamin d produced by macrophages. 

There's also usually an increased level of angiotensin-converting enzyme or ace which is produced by t cells, another helpful clue using bronchoalveolar lavage is finding elevated levels of t cells in the lungs, in that procedure a bronchoscope is passed through the mouth or nose into the lungs where fluid is squirted out and then recollected and examined. Now finally and the best way to diagnose Sarcoidosis is to do a biopsy people with Sarcoidosis who have minimal symptoms don't need treatment because most symptoms resolve spontaneously within a few weeks and complete the remission from Sarcoidosis typically happens within a few years, but if there are severe symptoms, steroids can be really helpful.

So that's Sarcoidosis let's just quickly go over the main point Sarcoidosis is a system-wide disease with non-caseating granulomas, These have t cells on the periphery and macrophages in the center, sometimes there are large multi-nucleated cells called langense giant cells which contain Shoremen and asteroid bodies, In most cases of Sarcoidosis individuals develop bilateral hyalure lymphadenopathy, erythema dosim and have elevated levels of ace or angiotensin-converting enzyme as well as raise calcium levels, fortunately, the disease tends to resolve spontaneously helping current and future clinicians focus to learn to retain and thrive.

 

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