Idiopathic Multicentric Castleman Disease Interactive Disease Awareness and Educational Tool for Pathologists

Background: Idiopathic multicentric Castleman disease (iMCD) is a rare systemic lymphoproliferative disease that is challenging to diagnose. Diagnostic criteria require the identification of characteristic histopathology in the context of supportive clinical, radiologic, and serologic findings. However, the histologic features of iMCD can be subtle and nonspecific, which delays an accurate diagnosis. Timely diagnosis and early intervention are essential to reduce patient mortality. Developing a disease awareness and educational tool for pathologists may support the identification of future iMCD cases.

Methods: International pathologists were identified to support the development of an interactive pathology tool for iMCD. To validate the tool, a selection of pathologists attended a virtual workshop to provide insight and help shape the content and format of the tool. Prior to workshop, attendees were asked to complete a 14-question survey on the diagnosis of iMCD, including exclusion of other diseases, conditions with similar histopathological features, and features specific to iMCD.

Results: The educational tool is currently in development and takes into consideration the varied diagnostic journeys in different centers/countries. Histopathologic criteria for iMCD require evaluation of the degree of plasmacytosis, regressed germinal centers, follicular dendritic cell proliferation, vascular proliferation, and hyperplastic germinal centers. While the differences between high grade (grade 3) and normal (grade 0) findings are straightforward, differentiating grade 1 from grade 2 (the diagnostic cut-off) is challenging and subjective. The tool will focus on these diagnostic grey-zones to include points of differentiation between Grades 1 and 2 iMCD, disease exclusion criteria, and the use of diagnostic images that can be explored. Thus far, development of the tool has shown there is a need for standardized disease terminology between pathologists, that the use of template reports and language guidance may support the diagnostic process, and that patient case studies and the use of real-world examples support disease recognition. The educational tool is anticipated to be ready for release in September 2022.

Conclusions: Diagnosis of iMCD is complex, and, despite the existence of well-established diagnostic criteria, pathological differentiation remains a challenge. Increasing awareness of iMCD-specifically the key diagnostic criteria-will assist with both timely diagnoses and the treatment of this disease.

Sabattini:Novartis: Speakers Bureau; EUSA Pharma: Consultancy, Speakers Bureau. Neff:EUSA Pharma: Consultancy, Speakers Bureau; Abbvie: Consultancy; Guidepoint Global: Consultancy. Alapat:EUSA Pharma: Consultancy. Tousseyn:EUSA Pharma: Consultancy, Speakers Bureau. Rymkiewicz:EUSA Pharma: Consultancy. Moura de Paula:EUSA Pharma: Consultancy, Speakers Bureau; Bayer: Consultancy; Foundation Medicine: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees. Kamarádová:EUSA Pharma: Consultancy. Montes Moreno:EUSA Pharma: Consultancy. Lade:EUSA Pharma: Consultancy.