Corey Casper, MD, MPH:There are multiple ways that you can classify Castleman’s disease. The traditional way to classify it was based on whether there is a single lymph node involved or multiple lymph nodes involved. A single lymph node or even a group of lymph nodes within a chain was called unicentric disease, or one center. On the other hand, there were patients who had multiple lymph node chains involved, and those patients were categorized as having multicentric disease. So, initially, when the disease was first described, there were these two different categories. Subsequently, people began to recognize that there are also subcategories based on what you see histopathologically, so what’s seen under the microscope. We know that there is something called a hyaline vascular variant, and this variant is exemplified by having a lymph node that has an expansion of plasma cells but also a blood vessel that tends to pierce it. Hyalinization is visualized within the terminal center. On the other hand, there’s another histologic variant, which is called the plasma cell variant. This variant actually is similar in appearance but is also characterized by having sheets of plasma cells in the interfollicular space.
Then, people began to recognize that there are not just two clinical variants, unicentric and multicentric, but there are also now two histologic types, plasma cell variant and hyaline vascular variant. We came to then know that a patient could have any combination of those four subtypes. For example, “y” could have unicentric hyaline vascular, unicentric plasma cell, multicentric hyaline vascular, multicentric plasma cell or even a mixed version where there are features of both [hyaline vascular or plasma cell] with multicentric disease. One might say there are five different sub-classifications of Castleman’s disease using those criteria.
There are further classifications or sub-classifications within the multicentric disease within the plasma cell variant. There are patients who have HIV co-infection and infection with human herpesvirus-8. These patients can have a plasmablastic version of Castleman’s disease, so that might be a sub-variant. And, finally, many people now are thinking about the disease in two different classifications: idiopathic multicentric Castleman’s disease and Castleman’s disease that’s attributed to a virus, human herpesvirus-8.
There are many different ways you can catalog the disease, but I think clinically what makes most sense to me is to think about it as unicentric or multicentric because that helps us, as clinicians, understand the extent of disease. And then the histologic sub-variant, hyaline vascular variant, and plasma cell variant have implications for the biology of the disease and have implications for how you might best treat it. So, for those reasons, I tend to think of that as my classification of the disease.
Corey Casper, MD, provides information on the diagnosis and treatment of patients with Castleman Disease (CD).