Hemophagocytotic Lymphohistiocytosis (HLH)

Genetic disorder associated with failure to establish an effective immune response to infection. Caused by normal but overactive histiocytes. Clinical features include fever, hepatomegaly, cytopenia, and neurologic abnormalities. Lethal if not treated.

HPLH 1; HLH 1

1:50,000 live births. Two forms are described: (1) primary or familial hemophagocytic lymphohistiocytosis (FHL), a heterogeneous autosomal recessive disorder, and (2) secondary or acquired HLH (related to systemic infection, immunodeficiency, or underlying malignancy).

Heterogeneous autosomal recessive inheritance for FLH.

Proliferation of activated macrophages and histiocytes, which phagocytose other cells (red and white blood cells, platelets), leading to the clinical symptoms. Spleen, lymph nodes, bone marrow, liver, and central nervous system are preferential sites of involvement. The role of perforin and NK cells has been evocated in familial forms.

Evocated by the association of fever, hepatosplenomegaly, cytopenia, hypofibrinogenemia, hypertriglyceridemia, and hemophagocytosis. Rash may occur. Frequently affects infants from birth to 18 months.

Patients can present with coagulopathy with an increased partial thromboplastin time. Jaundice is often present as a consequence of hyperbilirubinemia. Lymphadenopathy, malaise, anorexia with weight loss, and failure to thrive can occur. Neurologic abnormalities including seizures have been observed. The skin can be involved in a variety of ways; clinically best characterized as erythroderma, generalized purpuric macules and papules, or morbilliform eruptions.

Preoperative evaluation must concern localization of infection and identification of the causal agent. Preoperative laboratory investigations should include full blood count, liver function (bilirubinemia, albuminemia, aspartate aminotransferase, alanine aminotransferase), and triglyceride.

Strict asepsis is needed. Coagulopathy and thrombopenia should be corrected if necessary and may require more transfusions than expected. Regional anesthesia is not contraindicated but should be avoided in case of infection or severe thrombopenia.

Repeated nitrous oxide administration should be avoided. Hepatotoxic drugs or drugs with hepatic metabolism should be avoided. Prophylactic antibiotics may consider immunologic status.