Abstract
Introduction: Castleman's disease is a rare lymphoproliferative disorder presenting in two forms: unicentric, typically localized and benign, and multicentric, marked by widespread lymph node involvement and severe systemic inflammation. This case underscores the diagnostic challenges and clinical complexity of CD. Case presentation: 62 year old female with history of obesity, hypertension and asthma presented to an emergency department in March 2024 with acute dyspnea. While she was treated for an acute asthma exacerbation, a 5 cm mass was identified on CT chest. Follow-up with her PCP led to a PET scan, revealing a large left apical-posterior mass with internal calcifications with a 6.8 SUV. In May 2024, CT-guided biopsy at an outside facility showed abnormal lymphoid proliferation though cytogenetic testing was inconclusive. She was referred to our facility and in August 2024 she underwent EBUS biopsy of the apical mass and multiple lymph nodes. Fine needle aspiration biopsy of the lung mass was non diagnostic and mediastinal staging was negative for lymphoma or malignancy. Multidisciplinary review at our tumor board recommended surgical biopsy. Pathology from VATS procedure revealed focal Castleman-like changes, and she was referred to hematology-oncology for medical management. She has a follow up with thoracic surgery for possible lung mass excision. Discussion: This case illustrates the diagnostic complexities inherent to Castleman's disease, particularly when it presents with non-specific symptomatology and incidental radiographic findings. This patient's case highlights how minimally invasive biopsy with EBUS bronchoscopy and CT guided biopsy failed to establish a diagnosis often leading to a delay in diagnosis. In this case the discovery of a solitary mass on imaging raised suspicions of malignancy. Repeated biopsies were inconclusive underscoring the difficulty in diagnosing CD possibly due to its variable histopathologic features (Three histologic variants—hyaline vascular, plasma cell, and mixed all with Angio follicular proliferation) and lack of specific markers. Multicentric Castleman's disease (MCD) and unicentric Castleman's disease (UCD) can both display atypical lymphoid proliferation, and diagnostic clarity often requires multiple biopsies, advanced imaging, and, as in this case, collaborative decision-making via a tumor board. Conclusion: This reinforces the role of surgical biopsy in cases with ambiguous findings on less invasive biopsies, especially when clinical suspicion persists. This case also demonstrates possible diagnostic challenges and underscores the importance of a multidisciplinary approach for Castleman's disease in a patient with unexplained lung mass.