2026 Volume 21 Issue 3 Pages 316-320
Objective: To report a case of pyothorax-associated lymphoma that was difficult to distinguish from chronic expanding hematoma because of a prolonged stable clinical course and serum soluble interleukin-2 receptor levels that remained within the reference range.
Patient: An 82-year-old woman with a history of thoracoplasty presented with a calcified thoracic mass.
Results: The mass remained radiologically stable, and soluble interleukin-2 receptor levels remained within the reference range (423 U/mL) for more than 2 years. Because of her advanced age and the absence of specific tumor markers, invasive biopsy was deferred. The patient subsequently developed rapid disease progression with systemic metastases and markedly elevated soluble interleukin-2 receptor levels. Autopsy confirmed Epstein–Barr virus-positive diffuse large B-cell lymphoma.
Conclusion: Pyothorax-associated lymphoma may present with an indolent course and soluble interleukin-2 receptor levels within the reference range, particularly when the tumor is encapsulated. In elderly patients with chronic pyothorax, malignancy should not be excluded solely based on stable morphology and normal biomarkers; early functional imaging is recommended.
