| Langerhans cell histiocytosis | |
|---|---|
| Classification and external resources | |
Micrograph showing a Langerhans cell histiocytosis with the characteristic reniform Langerhans cells accompanied by abundant eosinophils. H&E stain. |
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| ICD-10 | D76.0 |
| ICD-9 | 202.5, 277.89, 516.5 |
| ICD-O: | M9752/3,M9751/1 |
| OMIM | 604856 |
| DiseasesDB | 5906 |
| eMedicine | derm/216 |
| MeSH | D006646 |
Langerhans cell Histiocytosis (LCH) is a rare disease involving clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes. Clinically, its manifestations range from isolated bone lesions to multisystem disease.
LCH is part of a group of clinical syndromes called histiocytoses, which are characterized by an abnormal proliferation of histiocytes (an archaic term for activated dendritic cells and macrophages). These diseases are related to other forms of abnormal proliferation of white blood cells, such as leukemias and lymphomas.
The disease has gone by several names, including Hand-Schüller-Christian disease, Abt-Letterer-Siwe disease, and histiocytosis X, until it was renamed in 1985 by the Histiocyte Society.[1]
Contents |
| Alternative names |
|---|
| Histiocytosis X
Histiocytosis X syndrome |
| Subordinate terms |
| Hand-Schüller-Christian disease
Letterer-Siwe disease |
The disease spectrum results from clonal accumulation and proliferation of cells resembling the epidermal dendritic cells called Langerhans cells, hence sometimes called dendritic cell histiocytosis. These cells in combination with lymphocytes, eosinophils, and normal histiocytes form typical LCH lesions that can be found in almost any organ.[2]
There are three types of histiocytoses: malignant (true histiocytic lymphomas), "reactive" (benign histiocytoses), Langerhans cell histiocytosis.[3]
"Reactive" in this context indicates that the abnormality may be due to a physiological reaction to infection. For example leukocytosis (proliferation of white blood cells) is a normal reaction to infection, and "histiocytes" are developmentally related to white blood cells.
LCH is traditionally divided into three groups: unifocal, multifocal unisystem, and multifocal multisystem.[3]
Pulmonary Langerhans cell histiocytosis (PLCH) is a unique form of LCH in that it occurs almost exclusively in cigarette smokers. It is now considered a form of smoking-related interstitial lung disease. Some patients recover completely after they stop smoking, but others develop long-term complications such as pulmonary fibrosis and pulmonary hypertension.
LCH usually affects children between 1 and 15 years old, with a peak incidence between 5 and 10 years of age. Among children under the age of 10, yearly incidence is thought to be 1 in 200,000;[6] and in adults even rarer, in about 1 in 560,000.[7] It has been reported in elderly but is vanishingly rare.[8] It is most prevalent in Caucasians, and affects males twice as often as females.
LCH is usually a sporadic and non-hereditary condition but familial clustering has been noted in limited number of cases. Hashimoto-Pritzker disease is a congenital self-healing variant of Hand-Schüller-Christian disease.[9]
LCH provokes a non-specific inflammatory response, which includes fever, lethargy, and weight loss. Organ involvement can also cause more specific symptoms.
Diagnosis is confirmed histologically by tissue biopsy. Hematoxylin-eosin stain of biopsy slide will show features of Langerhans cell e.g. distinct cell margin, pink granular cytoplasm. Presence of Birbeck granules on electron microscopy and immuno-cytochemical features e. g. CD1 positivity are more specific. Initially routine blood tests e.g. full blood count, liver function test, U&Es, bone profile are done to determine disease extent and rule out other causes. Radiology will show osteolytic bone lesions and damage to the lung. The latter may be evident in chest X-rays with micronodular and interstitial infiltrate in the mid and lower zone of lung, with sparing of the Costophrenic angle or honeycomb appearance in older lesions. MRI and CT may show infiltration in sella turcica. Assessment of endocrine function and bonemarrow biopsy are also performed when indicated.
Treatment is guided by extent of disease. Solitary bone lesion may be amenable through excision or limited radiation. However systemic diseases often require chemotherapy. Use of systemic steroid is common, singly or adjunct to chemotherapy. Local steroid cream is applied to skin lesions. Endocrine deficiency often require lifelong supplement e.g. desmopressin for diabetes insipidus which can be applied as nasal drop. Chemotherapeutic agents such as alkylating agents, antimetabolites, vinca alkaloids either singly or in combination can lead to complete remission in diffuse disease.
Excellent for single-focus disease. With multi-focal disease 60% have a chronic course, 30% achieve remission and mortality is up to 10%.[11]
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