Paediatrics: Langerhans cell histiocytosis

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a disorder of unknown cause with a wide range of presentations. It is not a malignant condition, but may behave like one in its severest forms. Usually managed by paediatric on-cologists.

Langerhans cells are normally found in skin, lymph nodes, and airways. LCH results from monoclonal proliferation and accumulation of histio-cytes, with the characteristics of Langerhans cells, in skin, bone, pituitary, CNS, lungs, intestines, spleen, or bone marrow. It may manifest as single-or multisystem disease. Single-system disease is usually confined to bone, occasionally to skin, and seen more in older children. The natural history varies from spontaneous resolution to repeated recurrence, or death.

Note: LCH was previously known as ‘histiocytosis X’, which was sub-divided into eosinophilic granuloma, Letterer–Siwe disease, and Hand– Schüller–Christian disease

Incidence 

Approximately 1 in 200,000 children affected each year.

Presentation Depends on site of disease, but may include:

·  Pain or lump associated with isolated bony disease (most common).

·  Skin rash (widespread macular–papular or mimicking seborrhoeic dermatitis of the scalp).

·  Discharge from the ear.

·  Diabetes insipidus.

·  Systemic disturbance (fever, malaise, anorexia, and failure to thrive).

Diagnosis

Biopsy with confirmation of Birbeck granules (or positivite CD1a or S100 immunohistochemistry). Diagnosis can be made without biopsy in the presence of characteristic pituitary/hypothalamic abnormality, where biopsy considered too hazardous, or of lytic bone lesions with clinical features suggesting spontaneous resolution.

Further investigation

Suspected LCH should be fully staged to identify possible multisystem disease. Investigations should include skeletal survey, abdominal ultra-sound, early morning urine for osmolality, FBC and film, coagulation stud-ies, and liver enzymes.

Treatment

·  Single system LCH, usually involving bone or skin, frequently resolves spontaneously or following biopsy/surgical curettage, but may require topical or intralesional steroids in persistent or recurrent cases.

·  Multisystem LCH, seen mainly in young patients (aged <2yrs), requires treatment with steroids and chemotherapy (vinblastine, etoposide, or methotrexate).

Prognosis

>80% survive long-term without significant sequelae. Survivors `of multisystem or CNS disease may have lasting disabilities.