Case Report: Extranodal NK/T-cell lymphoma with initial presentation in the lungs mimicking invasive fungal infection and an emerging hyperinflammatory state

Background Extranodal natural killer/T-cell lymphoma (ENKTL) with initial pulmonary presentation is exceptionally rare. Due to its characteristic angiodestructive growth pattern manifesting as CT “halo signs,” ENKTL is frequently misdiagnosed as invasive fungal infection, causing fatal treatment delays. Moreover, associated secondary hemophagocytic lymphohistiocytosis (HLH) progresses rapidly, yet conventional diagnostic criteria often lack sensitivity for emerging cytokine storm detection. Case presentation A middle-aged woman presented with progressive dyspnea. Chest CT revealed bilateral nodules with prominent “halo signs,” initially managed as refractory pneumonia. Subtle otolaryngological symptoms were overlooked due to severe lower respiratory distress. Following empirical antimicrobial failure, a CT-guided lung biopsy demonstrated marked angiodestructive lymphocytic infiltration with positive EBER in situ hybridization, confirming ENKTL. Subsequent sinus CT identified the primary nasopharyngeal lesion. Although full HLH-2004 criteria were not met, extreme hyperferritinemia (>5,000 ng/mL) indicated an emerging hyperinflammatory state. Poor performance status (ECOG 3–4) and pancytopenia precluded intensive chemotherapy. The disease progressed rapidly, leading to death shortly after discharge. Conclusion The major lesson from this case is that although the imaging finding of halo sign of the lungs usually indicates invasive fungal infection, biopsy of the lung lesion is mandatory for confirmation and exclusion of other diseases such as ENKTL in this case. Additionally, extreme hyperferritinemia serves as a critical sentinel marker for an emerging hyperinflammatory state, enabling earlier risk identification before irreversible cytokine storms develop.