Sequential Development of Waldenström's Macroglobulinemia After High-Grade Lymphomatoid Granulomatosis.

Lymphomatoid granulomatosis (LYG) is a rare Epstein-Barr virus-driven B-cell lymphoproliferative disease that often progresses to high-grade lymphoma. We describe a case of high-grade LYG causing Pancoast syndrome, diagnosed via transbronchial biopsy after a failed incisional biopsy. Complete remission was achieved with R-CHOP (rituximab, doxorubicin, cyclophosphamide, vincristine, and prednisolone), but 2.5 years later, the patient developed lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia (LPL/WM). Despite bendamustine-rituximab improving LPL/WM, LYG recurred, underscoring its treatment challenges. This case highlights LYG's diagnostic complexity, its potential link with other hematologic malignancies, and therapeutic limitations. Further research is needed to elucidate LYG's pathogenesis and develop effective treatments for relapsed cases.