Occult Malignancy Presenting as Pericardial Effusion: The Diagnostic Contribution of Pericardial Fluid Cytology

Background/Objectives: Pericardial effusion may occur in patients with established cancer but may also represent the first manifestation of an occult malignancy. This study evaluated the diagnostic contribution of pericardial fluid cytology and pathological assessment according to previous oncological status, with particular emphasis on previously unrecognized malignancy.

Methods

We conducted a retrospective observational study of patients hospitalized with pericardial disease between January 2021 and December 2025 at a tertiary cardiovascular center. The final cohort comprised 234 clinical episodes in 209 patients. Clinical, laboratory, imaging, procedural, cytological, and histopathological data were analyzed in relation to previous oncological status and malignant pericardial involvement.