Histiocytoses (Langerhans Cell Histiocytosis)

Key Points
Syndrome that involves the abnormal increase in the number of cells called histiocytes. More commonly seen in children
Spectrum of disease states/severity
Syndrome may attack skin, bones, organs, or other tissue
Unclear whether histiocytosis is a malignant (cancerous) or reactive condition
Rare, 1 in 200,000 children develop histiocytosis

Histiocytoses refers to a syndrome that involves an abnormal increase in the number of histiocytes ( in various tisssues), which are cells that are part of the immune system (normally, they originate in the bone marrow and migrate through the body via the bloodstream). Rather than fight infection, where this disease is present, histiocytes attack the body. The syndrome generally affects children from the age of 1 to 15, peaking in the 1 to 3 age group. There are three major classes of Langerhans cell histiocytotis (or Histiocytosis X), depending on which organs are invoved and to what extent . In the disseminated form (Letterer-Siwe disease) the presentation is small pinkish or reddish-brown bumps on the skin that may become crusted ; up to 80 percent of patients have eruptions on the scalp. Other symptoms may include vomiting, weight loss, mental deterioration, frequent urination, headaches, and limping, among other symptoms. If the disease is confined to one organ, such as solitary lesions of the bone or skin, often the disease is mild; if it affects multiple organs and, especially, if it affects children under the age of two, the disease can be severe or even fatal.

Differential Diagnosis (Other conditions with similar appearance)Mastocytosis
Acrodermatitis enteropathica
Seborrheic Dermatitis
Acropustulosis of infancy
Wiskott-Aldrich Syndrome

Diagnosis
Key Points
Appearance of rash
Tests vary depending on the age of the patient
In children, tests, may includes a Biopsy of the skin or tissue, a complete blood work-up, or X-rays

If a dermatologist sees a rash that is consistent with histiocytoses, further tests are taken, including skin or tissue biopsies, as well as CT scans to rule out internal involvement. If histiocytosis is diagnosed in one organ, other organs will be checked to see if they are also affected.

Treatment
antibiotics
steroid Injections
*chemotherapy in more extreme cases

If histiocytosis is limited to the skin, treatment may be conservative. Topical corticosteroids may be used to ease discomfort or address cosmetic concerns. If the disease is limited to the bones and there is a risk of deformity or fracture, more aggressive tactics may be taken, including the use of anti-inflammatory drugs, steroid Injections or limited radiation therapy. In cases where multiple organs are affected, chemotherapy is considered if oral corticosteroids is ineffective. Children under the age of two may require more aggressive chemotherapy.