Clinical Description
Chediak-Higashi syndrome (CHS) is characterized by partial oculocutaneous albinism (OCA), immunodeficiency, and a mild bleeding tendency. These features are present in nearly all individuals with CHS but to a very variable degree. Affected individuals with severe presentations (i.e., OCA; early-onset, recurrent, severe infections; and a bleeding diathesis) are considered to have "classic" CHS. Individuals with milder phenotypes (e.g., later-onset, milder pigmentary, immunologic, and hematologic features) are considered to have "atypical" CHS (also referred to as "mild" or "adolescent" CHS). Both groups of individuals are at risk of developing hemophagocytic lymphohistiocytosis (HLH), previously called "the accelerated phase," with the highest risk of HLH (~85%) in individuals with classic CHS.
Over time, it has become apparent that the classification of CHS into "classic" vs "atypical" phenotypes is arbitrary, as the considerable overlap of the two groups means that this disorder is best understood as a continuum of severe to milder phenotypes, with the universal feature being the pathognomonic giant granules within leukocytes observed on peripheral blood smear.
Although the proportion of individuals with atypical CHS is unknown [Karim et al 2002, Westbroek et al 2007], it is likely underrecognized. In some individuals with atypical CHS, the neurologic findings may be the predominant manifestation. Additionally, some individuals may not be diagnosed until the third decade of life or later [Weisfeld-Adams et al 2013, Yarnell et al 2020].
Table 2.
Chediak-Higashi Syndrome: Phenotypic Continuum
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Feature | Degree of Involvement 1 |
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Oculocutaneous albinism | Ranges from mild/moderate in classic CHS to mild/absent in atypical CHS |
Immunodeficiency / increased risk of infection | Ranges from infantile onset of frequent and often severe infections in classic CHS to absence of a noticeable increase in severity or frequency of infections in atypical CHS |
Bleeding tendency | Similar bleeding diathesis in all individuals with CHS |
Neurologic involvement | Wide-ranging and nonspecific features in all individuals with CHS. |
Hemophagocytic lymphohistiocytosis 2 | Occurs in the majority of individuals with CHS who have not undergone hematopoietic stem cell transplantation. |
- 1.
The same CHS-related features are present in nearly all individuals with classic and atypical CHS but to a very variable degree.
- 2.
Also called "accelerated phase"
Partial oculocutaneous albinism (OCA). Pigment dilution, which can involve eyes, hair, and skin, is highly variable.
Reduced iris pigmentation and iris transillumination may be subtle. Affected individuals may have decreased retinal pigmentation and nystagmus. Visual acuity varies from normal to moderately reduced.
The hair has a "silvery" or metallic appearance. Pigment clumping within the shaft of the hair is generally observed by light microscopy () [Smith et al 2005].
Skin pigment dilution may not be appreciated unless compared to the pigmentation of family members. Individuals with darker skin tone may observe areas with scattered hyper- and hypopigmentation.
Although partial OCA was once thought to be a diagnostic criterion for CHS, at least two individuals with atypical CHS had no evidence of OCA [Introne et al 2017].
Immunodeficiency. Frequent infections usually begin in infancy and are often severe in classic CHS. Individuals with atypical CHS may not have a noticeable increase in severity or frequency of infections.
Bacterial infections are most common, with Staphylococcus and Streptococcus species predominating; viral and fungal infections can also occur [Introne et al 1999]. Infections of the skin and upper respiratory tract are the most common.
Periodontitis, an important manifestation of immunologic dysfunction [Thumbigere Math et al 2018, de Arruda et al 2023], can be the clinical finding that leads to the correct diagnosis [Bailleul-Forestier et al 2008].
Neutropenia may be present and, in some individuals, cycles between normal absolute neutrophil counts and neutropenia (also called "cyclic neutropenia").
Bleeding tendency. The bleeding diathesis in CHS, a result of absent or severely reduced platelet-dense granules, is present in both classic and atypical CHS. Clinical manifestations are generally mild and include epistaxis, gum/mucosal bleeding, and easy bruising. The bleeding diathesis may also be subtle (i.e., generally not requiring medical intervention) and thus may not be identified as a health concern by affected persons. However, with trauma or invasive procedures, bleeding may be more severe and prolonged.
Neurologic involvement. Despite successful hematologic and immunologic outcomes with allogenic hematopoietic stem cell transplantation (HSCT) to treat hematologic findings, neurologic involvement nonetheless manifests by early adulthood.
Neurologic features are similar across the CHS phenotypic spectrum; thus, individuals with classic and atypical CHS cannot be distinguished neurologically [Introne et al 2017]. Due to the wide range of neurologic features that can occur, findings among affected individuals are variable and nonspecific. Likewise, age of onset and disease progression also vary. While learning difficulties may be present in childhood and can be considered developmental in nature, other neurologic signs and symptoms are generally not observed until late adolescence or early adulthood and are progressive. Neurologic findings can include:
Sensory neuropathy. Onset in late adolescence or early third decade and slowly progresses to sensorimotor neuropathies and/or diffuse motor neuronopathy [
Lehky et al 2017]
Optic neuropathy. Onset in late adolescence or early adulthood [
Desai et al 2016]
Tremor, which can include kinetic and postural tremor
Progressive cognitive decline late in the disease course
Hemophagocytic lymphohistiocytosis (HLH; also known as the "accelerated phase") occurs in the majority of individuals with CHS who have not undergone HSCT [Lozano et al 2014] and can occur at any age. Although individuals with atypical CHS are thought to be at lower risk of HLH than individuals with classic CHS, the frequency of occurrence in atypical CHS is unknown.
Originally thought to be a malignancy resembling lymphoma, the "accelerated phase" is now known to be HLH characterized by multiorgan inflammation. Manifestations include fever, lymphadenopathy, hepatosplenomegaly, anemia, neutropenia, and thrombocytopenia.
Triggers of HLH remain unclear. Although infection with Epstein-Barr virus is thought to hasten development of HLH, this relationship has never been proven. Abnormal function of NK cells and cytolytic T cells is also believed to contribute to development of HLH [Jessen et al 2011, Gil-Krzewska et al 2016].
Prognosis. HLH and its complications are the most common cause of mortality in individuals with CHS [Lozano et al 2014].