| Transcript |
So, today we're going to be talking about the histiocyte and the histiocytic disorders, just in neuro-oph. Obviously, we're not going to be covering the whole hematology of histiocyte because that would take too long, but you need to know though, is there are precursor cells, and those precursor cells form the basis of the histiocytic lesions that we see and that can be either in the monocyte line, or the macrophage line, or in the dendritic cell. As you remember, the dendritic cell, the monocyte, and the macrophage are all part of our immune system, but they're part of a special part of the immune system called areticulo endothelial system, so these cells are very specialized cells for eating stuff and that's what phage means. So, he's a big eater, this macrophage. So, we can have tumors derived from these cell types, and they can either be of the Langerhans cell histiocyte type, or the non-Langerhans cell histiocyte type. The monocytes also can make leukemia and malignancies. That's chronic myeloid monocytic leukemia. And you should look at the videos on leukemias for those as well as anemic retinopathy in those patients. Today we're going to concentrate on these two characteristics, which is the Langerhans type and the non-Langerhans type, and how that comes to the neuro-oph. So, the way it comes to neuro-oph, even though both of these can cause histiocytic infiltration in multiple organ systems, and that means it can be in your heart and it can be in your lung, and it can be in your retroperitoneum, the ones that come to us are the ones that are the dural based ones and the ones that affect the orbit. So, the dural based ones can produce optic neuropathies or cranial neuropathies that might come to us as double vision or loss of vision. The orbital ones come to us as a bilateral mass. And so, in the non-Langerhans cell type we have a special type, which is called sinus histiocytosis with massive lymphadenopathy, so if we're doing a chart biopsy on this chart of a patient with dural lesions or orbital lesions and we encounter that they've had imaging studies that show massive cervical or abdominal or thoracic massive lymphadenopathy, that disorder is called the Rosai-Dorfman Disorder. And it's kind of a funny name - Rosai and Dorfman, and that's good and it's bad. It's weird but it's also weird that you can remember it .The Rosai-Dorfman Syndrome, a macrophage disorder of the non-Langerhans cell type characterized by massive lymphadenopathy and the sinus histiocytosis, can come to us as dural based infiltration orbilateral orbital mass. In the Rosai-Dorfman, the path, as with all of these, is critical, because you really can't tell it's a histiocyte from the MRI scanner, from the orbit evaluation, and so, the pathfinding is called emperipolesis, and what this means is you have an intracytoplasmic lymphocyte, the lymphocyte himself was eaten by the macrophage, so inside the macrophage is another cell, and that's what emperipolesis means. "Em" means in, "peri" means around, so the whole macrophages is eating macrophage and big eater of what he's not supposed to be eating, which is you. And the other form of this is called Erdheim-Chester, Erdheim-Chester Disorder. Also a very weird name, Erdheim and Chester, and Erdheim-Chester also can produce dural based lesions, orbital lesions, it does not have the emperipolesis on the path and it doesn't have the massive lymphadenopathy what-what Erdheim-Chester looks like is slightly different than what Rosai-Dorfman looks like, what you really need the path, but they both share this piece right here, which is the dural based enhancing lesion and the bilateral orbital masses. The only way to know what that is, however, is the biopsy. The Langerhans cell histiocytosis can occur in different organ systems, retroperitoneal like in Erdheim-Chester, or really anywhere in the body, and so when you look at the chart and there's all these organ systems having infiltration, lymphadenopathy, retroperitoneum, perinephric, when you see that in the chart, you really should be thinking maybe this is an infiltrate of neoplastic process that can be benign or malignant and if it's the Langerhans cell type that used to have names like Hand-Schuller Christian Disorder, where they have diabetes insipidus and Letterer-Siwe, which is a fatal juvenile form, but really we don't call on any of those anymore, we just call them all Langerhans cell histiocytosis. So again, the way this comes to us is dural based or orbital lesions, infiltrative process, histiocytic should be on the differential as well as lymphocytic and you need a biopsy to differentiate them. |
