LCH in Adults
Diagnosis and Treatment
A diagnosis of Langerhans cell histiocytosis (LCH) is made following a biopsy and microscopic examination of the affected tissue. If the biopsy is positive for LCH, some other tests may be carried out to determine the extent of disease so that a treatment plan can be made. These may include skeletal x-ray survey with skull x-ray series, bone scan, blood tests (complete blood count, sedimentation rate, liver function tests, electrolytes), and urine tests. If there are symptoms of diabetes insipidus, a water-deprivation test should be done. When the bones near the ears or eyes are involved, a head CT scan is indicated. An MRI of the brain may be necessary if the lesions are near the eyes or ears or there is suspicion of central nervous system (CNS) involvement. Chest CT and lung function studies are performed when indicated. Other testing may be done, depending on symptoms. Other biopsies may be performed if test results or abnormal findings during the physical exam cause the physician to suspect involvement of another area.
When lung involvement is suspected, a chest x-ray is usually done and is abnormal in most patients. These abnormalities are subtle, can be easily missed, or can be mistaken for other diseases such as emphysema. The most common abnormality (in 70% to 90% of cases) is a reduced DLCO, which is a lung function test that measures the rate which carbon dioxide moves from the lung to the blood. The most sensitive diagnostic test is a high-resolution CT scan (HRCT), another type of x-ray, which can reveal lung cysts that are characteristic of LCH. It is possible to make a diagnosis with a bronchoalveolar lavage (BAL). The BAL is a medical procedure in which a tube is passed through the mouth or nose into the lungs, and fluid is squirted into part of the lung and then collected for examination. If the BAL and HRCT do not provide a diagnosis, then surgical lung biopsy may be necessary. In patients with diagnosed LCH in other areas of the body such as skin or bone, the diagnosis of lung involvement can be made if the HRCT shows findings consistent with pulmonary Langerhans cell histiocytosis (PLCH).
There is no established, widely agreed-upon treatment of LCH in general. It depends upon the individual patient and the extent and areas of involvement. Some patients have had success with vinblastine (chemotherapy) and steroids, while others have benefited from limited surgery, other chemotherapy agents such as 2-chlorodeoxyadenosine (2CdA) or methotrexate, and even low-dose external beam irradiation. Some patients may have limited involvement, which does not progress to other areas and may not need systemic treatment.
There are medications called “targeted therapies” which block the activity of genes with mutations in them. For example, there are medications that block mutations in BRAF specifically. In small clinical trials, these medicines have been very effective in treating LCH. These treatments should be considered for certain instances of LCH, such as severe cases or those for which other treatments have not been successful. Targeted treatments for genes other than BRAF are under investigation.
In cases of pulmonary LCH, an essential part of treatment is discontinuing cigarette smoking or smoking of illegal drugs. In some cases, this can lead to stabilization of symptoms and even improvement. There are no established guidelines for the treatment of PLCH; however, some patients are treated with steroids, while others may receive treatment with systemic chemotherapy agents such as vinblastine, 2-CdA, cyclophosphamide, methotrexate, and even thalidomide. A small number of patients develop severe and disabling lung disease and may require a lung transplant.
Even if it is determined that no treatment is necessary at the time of diagnosis, the physician will likely monitor the disease regularly to be sure that there is not further progression of the existing areas and that new areas of involvement can be detected and treated early. The ultimate goal of an overall treatment plan, of course, is to use as little treatment as possible to keep the disease under control to preserve quality of life and prevent the histiocytosis from damaging vital organs.