BCG lymphadenitis in neonates with familial hemophagocytic lymphohistiocytosis

Bacteria-Associated Cytokine Storm Syndrome

While viruses are considered the most common infectious triggers for cytokine storm syndromes (CSS), a growing list of bacterial pathogens, particularly intracellular organisms, have been frequently reported to be associated with this syndrome. Both familial and sporadic cases of CSS are often precipitated by acute infections. It is also important to note that an underlying precipitating infection might not be clinically obvious as the CSS clinical picture can mimic an infectious process or an overwhelming septicemia. It is important to detect such an underlying treatable condition. In addition, infections can also be acquired during the course of CSS due to the concurrent immune suppression with treatment. Optimal CSS outcomes require treating bacterial infections when recognized.CSS should always be suspected in patients presenting with a sepsis-like or multi-organ dysfunction picture. There are many criteria proposed to diagnose CSS in general, with HLH-2004 being the most commonly used. Alternatively, criteria have been proposed for CSS occurring in specific underlying conditions such as systemic lupus erythematosus (SLE) or systemic juvenile idiopathic arthritis (sJIA). However, waiting for many of these criteria to be fulfilled could lead to significant delay in diagnosis, and the physician needs a high index of suspicion for CSS in critically ill febrile hospitalized patients in order to properly recognize the condition. Thus, there should be diagnostic equipoise between CSS and infections, including bacterial, in this population. In this chapter, we discuss the more common bacterial precipitants of CSS with many of the cases being discussed in the pediatric age group.

Macrophage Activation Syndrome

Hemophagocytic lymphohistiocytosis (HLH), or termed macrophage activation syndrome (MAS) when associated with rheumatic disorders, is a frequently fatal complication of infections, rheumatic disorders, and hematopoietic malignancies. Clinically, HLH/MAS is a life-threatening condition that is usually diagnosed among febrile hospitalized patients (children and adults) who commonly present with unremitting fever and a shock-like multiorgan dysfunction scenario. Laboratory studies reveal pancytopenia, elevated liver enzymes, elevated markers of inflammation (ESR, CRP), hyperferritinemia, and features of coagulopathy. In about 60% of cases, excess hemophagocytosis (macrophages/histiocytes engulfing other hematopoietic cell types) is noted on biopsy specimens from the bone marrow, liver, lymph nodes, and other organs. HLH/MAS has been hypothesized to occur when a threshold level of inflammation has been achieved, and genetic and environmental risk factors are believed to contribute to the hyperinflammatory state. A broad variety of infections, from viruses to fungi to bacteria, have been identified as triggers of HLH/MAS, either in isolation or in addition to an underlying inflammatory disease state. Certain infections, particularly by members of the herpesvirus family, are the most notorious triggers of HLH/MAS. Treatment for infection-triggered MAS requires therapy for both the underlying infection and dampening of the hyperactive immune response.

Sepsis due to Streptococcus pneumoniae associated with secondary hemophagocytic lymphohistiocytosis in a splenectomized patient for spherocytosis: A case report

RATIONALE

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome that is characterized by an inappropriate hyperinflammatory immune response - primary, as a consequence of a genetic defect of NK cells and cytotoxic T lymphocytes or - secondary, in the progression of infections, rheumatic or autoimmune diseases, malignancies or metabolic diseases.

PATIENT CONCERNS

We present the case of a secondary HLH due to Streptococcus pneumoniae infection in a splenectomised patient for spherocytosis, a 37-year-old patient who was splenectomised in childhood for spherocytosis, without immuneprophylaxis induced by antipneumococcal vaccine.

OUTCOMES

He developed a severe pneumococcal sepsis associated with secondary HLH, with unfavorable outcome and death.

LESSONS

To our knowledge, just 2 similar cases had been published in the literature, none in which the secondary HLH was the consequence of an invasive pneumococcal infection in a splenectomized patient for spherocytosis, and the association of splenectomy with HLH is surprizin.

Hemophagocytic lymphohistiocytosis: review of etiologies and management

Hemophagocytic lymphohistiocytosis (HLH) covers a wide array of related life-threatening conditions featuring ineffective immunity characterized by an uncontrolled hyperinflammatory response. HLH is often triggered by infection. Familial forms result from genetic defects in natural killer cells and cytotoxic T-cells, typically affecting perforin and intracellular vesicles. HLH is likely under-recognized, which contributes to its high morbidity and mortality. Early recognition is crucial for any reasonable attempt at curative therapy to be made. Current treatment regimens include immunosuppression, immune modulation, chemotherapy, and biological response modification, followed by hematopoietic stem-cell transplant (bone marrow transplant). A number of recent studies have contributed to the understanding of HLH pathophysiology, leading to alternate treatment options; however, much work remains to raise awareness and improve the high morbidity and mortality of these complex conditions.