Case Report: Clinical characteristics and outcomes in natural killer (NK)/T-cell lymphomas with cardiac involvement: a case series and literature review.

Background: Cardiac involvement by extranodal natural killer/T-cell lymphoma (ENKTL) and aggressive NK-cell leukaemia (ANKL) is exceedingly rare and presents with heterogeneous manifestations, often leading to diagnostic uncertainty and delay. We contribute three additional biopsy- or autopsy-proven cases and place them in the context of a literature review of previously reported cases classified according to the 5th edition of the World Health Organization (WHO) Classification of Hematolymphoid Tumors. Case series: Three men (ages 58-72) presented with diverse cardiac manifestations. A 72-year-old with progressive dyspnoea and cardiogenic shock had cMRI findings interpreted as myocarditis on an infiltrative substrate; endomyocardial biopsy confirmed cardiac infiltration by ENKTL. Despite brentuximab vedotin (BV)-based therapy he died shortly thereafter. A 60-year-old with encephalopathy, biventricular dysfunction, and widespread nodal/multiorgan disease had nodal pathology consistent with EBV-negative ANKL according to the criteria of the 5th edition of the WHO Classification of Hematolymphoid Tumors; he declined chemotherapy and died within six days, with autopsy confirming multiorgan (including myocardial and bone marrow) infiltration. A 58-year-old with prior sinonasal ENKTL treated with four cycles of SMILE developed a new right atrial mass one month later; the mass was diagnosed by cMRI/PET-CT concordance and an extracardiac (EBUS-lung) tissue confirmation of the same recurrence. BV followed by gemcitabine/oxaliplatin failed to control progression and he died approximately one month after cardiac spread. Across cases, CD56 was positive in all, EBER in two, and CD30 was expressed variably. Conclusions: Cardiac ENKTL/ANKL is a rapidly fatal entity with protean features. Multimodal imaging aids early recognition and tissue targeting, but definitive diagnosis rests on tissue confirmation. L-asparaginase-based chemotherapy remains the treatment backbone; CD30- and PD-L1-guided agents such as BV, PD-1 blockade, and daratumumab may offer transient control after biomarker-guided selection but lack randomized data in cardiac disease. Across the reported experience, survival after cardiac involvement was uniformly short, typically days to a few months. Our three cases add to this literature by illustrating the diversity of cardiac presentations, the variable CD30 expression relevant to brentuximab vedotin use, and the contribution of multimodal imaging to diagnosis. Findings from our series and the pooled literature are descriptive rather than constituting a formal survival analysis, and underscore the need for earlier diagnosis and prospective investigation.