Castleman Disease in an Older Patient With the Onset of Right Pleural Effusion.

Castleman's disease (CD) is an uncommon lymphoproliferative disorder with various presentations in different age groups. Although CD predominantly affects younger individuals, cases in older people are rare. The presentation of CD can range from asymptomatic to severe. We present the case of a 91-year-old male who reported dyspnea and was subsequently diagnosed with right-sided pleural effusion. The patient's condition deteriorated despite an initial provisional diagnosis of tuberculous pleurisy and multiple interventions. A cervical lymph node biopsy later revealed a diagnosis consistent with the plasma cell type of CD. Considering the patient's age and atypical presentation, this case adds a unique perspective to the limited literature on CD in elderly patients. Its presentation can be highly variable, and pleural effusion is rare. Our case highlights the heterogeneity of CD presentation, particularly in older age groups. The diagnosis of CD requires high suspicion, particularly in non-traditional populations. Clinicians should be aware of the varied presentations of CD, including in older patients. Unexplained pleural effusion, even in older patients, should prompt a broad differential diagnosis, including rare conditions such as CD.