A Case Report of Hemophagocytic Lymphohistiocytosis (HLH) - An Unusual Complication of Dengue Infection

Abstract

Hemophagocytic lymphohistiocytosis (HLH) is an autoimmune phenomenon characterized by reactive hyperactivity of cytotoxic T cells and histiocytes, leading to hypercytokinemic injury to cells and organ system, which leads to multiorgan dysfunction and ultimate failure. Epstein-Barr virus (EBV) is most commonly associated with secondary HLH with high mortality, but increasing evidence suggests the association of the dengue virus. When associated with dengue infection, it carries a grave prognosis and correlates with the disease severity. Furthermore, it overlaps with dengue sepsis, so it can often be misdiagnosed as sepsis. Typically the patients have hyperferritinemia, hypertriglyceridemia, transaminitis, and marrow features suggestive of hemophagocytosis. The treatment is usually systemic corticosteroids, intravenous immunoglobulin, and chemotherapy with etoposide. We present a case of a 25-year-old male patient who had a dengue infection and further developed HLH with pulmonary infiltrates. Clinical suspicion alerted us to look for other evidence of HLH on the fourth day of admission, and appropriate investigations were done. Diagnosis of HLH was confirmed by HLH-2004, HScore criteria, and bone marrow aspirate examination. Treatment was given in the form of corticosteroids and chemotherapy along with other supportive measures. The patient responded to the line of management.

Keywords: autoimmune; autosomal; cytotoxic; hyperferritinemia; neoplasm.

Figure 1. Chest X-ray showing bilateral infiltrates in lung fields

Figure 2. HRCT of lungs showing multiple ill-defined patchy ground-glass opacities with septal thickening and patchy areas of consolidation in bilateral lung fields

HRCT - high-definition computed tomography

Figure 3. High power fields (400x) of a bone marrow aspirate smear demonstrating histiocytes showing features of hemophagocytosis of the leucocytes (grey arrow), platelets (white arrow), and mature erythrocytes (black arrow), features suggestive of HLH

HLH - hemophagocytic lymphohistiocytosis

Figure 4. High power fields (400x) of a bone marrow aspirate smear demonstrating a histiocyte with an engulfed neutrophil (arrow) and mature erythrocytes within (arrowhead), suggesting hemophagocytic lymphohistiocytosis.