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

Summary 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.