The application of a multidisciplinary approach in the diagnosis of Castleman disease and Castleman‐like lymphadenopathies: A 20‐year retrospective analysis of clinical and pathological features

Background: Castleman disease (CD) comprises a group of rare and heterogeneous haematological disorders, including unicentric (UCD) and multicentric (MCD) forms, the latter further subdivided into HHV8-MCD, POEMS-MCD and idiopathic-MCD (iMCD). However, according to the Castleman Disease Collaborative Network guidelines, the diagnosis of CD can only be achieved through collaboration between clinicians and pathologists. Methods: We applied these clinical and pathological criteria and implement with clonality testing to a retrospective cohort of 48 adult and paediatric Italian patients diagnosed with reactive lymphadenitis with CD-like histological features. Results: We confirmed the diagnosis of CD in 60% (29/48) of the cases, including 12 (41%) UCD and 17 (59%; five HHV8-MCD, three POEMS-MCD and nine iMCD) MCD. Of the remaining 19 cases (40%) with multiple lymphadenopathy, 5 (26%) were classified as autoimmune diseases, 1 (5%) as autoimmune lymphoproliferative disorder, 1 (5%) as IgG4-related disease, 11 (83%) as reactive lymphadenitis and 1 (5%) as nodal marginal zone lymphoma. Conclusions: Our study emphasizes the importance of the multidisciplinary approach to reactive lymphadenitis with CD-like features in order to achieve a definitive diagnosis and choose the appropriate treatment.