Through the development of this tool, a series of frequently asked questions (FAQs) deemed relevant by our expert panel were identifed.
FREQUENTLY ASKED QUESTIONS (FAQs)
Can iMCD be diagnosed using histopathology alone?
No, a diagnosis of iMCD is made based on the presence of specific histopathological characteristics, as well as the clinical picture and key exclusions.
How should I grade the diagnostic morphological patterns e.g., regressed germinal centres?
Some visual guidance is included in the international diagnostic guidelines. Further guidance can be found in this tool. While not an established metric, several experts involved in the development of this tool use a 50% threshold to determine Grade 2 and above, i.e., a sample with more than 50% regressed germinal centres can be considered Grade 2-3.
Can lymphomas mimic CD-like morphological changes and vice versa?
Yes. Careful consideration and exclusion of lymphomas is important. Additional information is available in the international diagnostic guidelines.
Why is an excisional lymph node biopsy required, are other biopsies never suitable?
Non-excisional samples may allow you to assess some of the features of iMCD, but as the node is not complete, they can give a false impression of the full histopathological patterns and thus return a false negative.
Is a bone marrow biopsy helpful in the assessment of iMCD?
Bone marrow core biopsy can help rule out plasma cell neoplasia. Bone marrow biopsies in iMCD patients may show megakaryocytic hyperplasia, mild polytypic plasmacytosis, and variable degrees of reticulin fibrosis. If you suspect Castleman Disease following
an assessment of a bone marrow biopsy, it is important to request an excisional lymph node biopsy.
Abbreviations
CD, Castleman Disease; FAQ, freqently asked questions; iMCD, idiopathic Multicentric Castleman Disease.
