Indolent NK-cell lymphoproliferative disorder of the gastrointestinal tract complicated by protein-losing enteropathy: A case report.

Background: Indolent NK-cell lymphoproliferative disorder of the gastrointestinal tract (iNKLPD) is a rare and recently defined entity, recognized in the 2022 WHO classification of hematolymphoid tumors. iNKLPD typically exhibits a benign or slowly progressive clinical course, with disease localized to the gastrointestinal tract. Here, we present what we believe to be the first reported case of iNKLPD associated with protein-losing enteropathy (PLE), characterized by a poor response to chemotherapy and rapid clinical deterioration, culminating in death within a few months.

Case summary: We report the case of a 64-year-old man who presented with bilateral lower-extremity edema and fatigue. Laboratory tests revealed marked hypoalbuminemia, while other liver function parameters remained within normal limits. Renal and cardiac function assessments were unremarkable. Histopathological examination of endoscopic biopsies confirmed a diagnosis of iNKLPD of the gastrointestinal tract. The patient was treated with oral prednisone and cyclosporine, which led to temporary improvement in both symptoms and serum albumin levels. However, disease relapse occurred during corticosteroid tapering, accompanied by worsening hypoalbuminemia and refractory diarrhea. The patient died eight months after diagnosis, likely due to disease progression or severe treatment-related complications.

Conclusion: iNKLPD generally exhibits an indolent course; nonetheless, the prognosis may be poor if secondary PLE is involved.