The Langerhans cell histiocytosis X files revealed

Langerhans cell histiocytosis: current advances in molecular pathogenesis

Langerhans cell histiocytosis (LCH) is a rare and clinically heterogeneous hematological disease characterized by the accumulation of mononuclear phagocytes in various tissues and organs. LCH is often characterized by activating mutations of the mitogen-activated protein kinase (MAPK) pathway with BRAFV600E being the most recurrent mutation. Although this discovery has greatly helped in understanding the disease and in developing better investigational tools, the process of malignant transformation and the cell of origin are still not fully understood. In this review, we focus on the newest updates regarding the molecular pathogenesis of LCH and novel suggested pathways with treatment potential.

Langerhans cell histiocytosis in adults: literature review

Langerhans cells histiocytosis is a variant of malignant histiocytosis. The course and symptoms vary. patients with localized forms have a better prognosis, because local therapy is effective. patients with multifocal forms of histiocytosis receive systemic drug therapy, which cures some of the patients. This review provides up-to-date data about typical presentation of the organ involvement, diagnosis, course and therapy of various forms of Langerhans cells histiocytosis.

[Dental-craniofacial manifestation and treatment of rare diseases in China]

Rare diseases are genetic, chronic, and incurable disorders with relatively low prevalence. Thus, diagnosis and management strategies for such diseases are currently limited. This situation is exacerbated by insufficient medical sources for these diseases. The National Health and Health Committee of China recently first provided a clear definition of 121 rare diseases in the Chinese population. In this study, we summarize several dental-craniofacial manifestations associated with some rare diseases to provide a reference for dentists and oral maxillofacial surgeons aiming at fast-tracking diagnosis for the management of these rare diseases.

Dental-craniofacial manifestation and treatment of rare diseases

Rare diseases are usually genetic, chronic and incurable disorders with a relatively low incidence. Developments in the diagnosis and management of rare diseases have been relatively slow due to a lack of sufficient profit motivation and market to attract research by companies. However, due to the attention of government and society as well as economic development, rare diseases have been gradually become an increasing concern. As several dental-craniofacial manifestations are associated with rare diseases, we summarize them in this study to help dentists and oral maxillofacial surgeons provide an early diagnosis and subsequent management for patients with these rare diseases.

Selected Giant Cell Rich Lesions of the Temporal Bone

Giant cell rich lesions of the temporal bone encompass a wide spectrum of disease that includes infectious, reactive, and neoplastic processes. When dealing with any lesion that can potentially involve bone, it is important to understand both the clinical presentation and to correlate the histologic findings with the radiologic imaging. This review discusses the clinical, the pathologic features including the differential diagnosis, and the treatment of some of the more commonly encountered giant cell rich entities in this region.

Langerhans cell histiocytosis: Skin diseases and visceral lesions

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder that belongs to class I histiocytoses and is characterized by infiltration of one or many organs by Langerhans cells to form granulomas. The literature analysis could identify a lot of etiological, pathogenetic, and trigger factors and mechanisms for LCH development, which determine the diversity of the clinical picture and course of the disease. The clinical manifestations of LCH are very variable and depend on the severity of lesions and the age of patients. In addition to skin lesions, there is involvement of one or more visceral organs. Difficulties in diagnosing the disease lead to statistical variations of LCH in different countries of the world and require more attention by physicians of all specialties.

Langerhans Cell Histiocytosis and Langerhans Cell Sarcoma: Current Understanding and Differential Diagnosis

Langerhans cell (LC) histiocytosis (LCH) and LC sarcoma (LCS) are proliferative processes consisting of cells having morphologic and phenotypic features of Langerhans cells (LCs), although the latter may have lost some of these features. Because neoplastic nature of LCH as well as LCS is more likely by recent studies, a category of LC hyperplasia can be better characterized. LCH and LCS are rarely seen in daily pathology practice, but it is important to accurately characterize these lesions. For this purpose, an outline covering proliferations of LC and related cells was constructed. The scheme of this outline is based especially on evaluating borderline lesions, neoplastic trans-differentiation, and degree of similarity with the normal counter-parts. In addition, the organization and update of the current classification scheme for histiocytic and dendritic-cell proliferations is presented.

Langerhans cell histiocytosis: a comprehensive review

Langerhans cell histiocytosis (LCH) is currently regarded as a myeloid neoplasm, with remarkably broad clinical spectrum, ranging from isolated skin or bone lesions to a disseminated disease that can involve nearly any organ. LCH is generally regarded as a sporadic disease that occurs predominantly in the paediatric population. The diagnosis of LCH is confirmed by immunohistochemistry (IHC) by demonstrating the presence of dendritic cell markers such as S100 protein, in addition to CD1a and langerin. Contrary to previous beliefs, recent literature reveals that the pathogenesis of LCH might involve a clonal process implicating BRAF c.1799T>A (p.Val600Glu) and other mutations [(600DLAT) B-RAF and (T599A) B-RAF, somatic MAP2K1 mutations].Through this review article, we have summarised the latest understanding of the biological and salient histological characteristics of LCH and its potential morphological mimics.

Interleukin-1 loop model for pathogenesis of Langerhans cell histiocytosis

We propose Langerhans cell histiocytosis (LCH) is an inflammatory process that is prolonged by mutations. We hypothesize that Merkel cell polyomavirus (MCPyV) infection triggers an interleukin-1 (IL-1) activation loop that underlies the pathogenesis of LCH. Langerhans cells (LCs) are antigen presenting cells in the skin. When LCs encounter exogenous antigens, they migrate from the epidermis into draining lymphoid tissues to initiate T-cell activity. It has been proposed that LC migration-related factors, including E-cadherin, matrix metalloproteinase, and Notch ligand induce LCH activity. We found that the tyrosine phosphatase SHP-1, which binds IL-1 receptor-associated kinase 1, is expressed at a significantly higher level in LCH affecting multiple organ systems (MS-LCH) than in LCH affecting a single organ system (SS-LCH). IL-1 stimulates T helper 17 cells and their signature cytokine IL-17 had been a matter of controversy. We detected higher levels of IL-17A receptor expression in MS-LCH than in SS-LCH and proposed an IL-17 endocrine model that could settle the controversy. IL-1 is the first cytokine secreted in response to sensitizers and promotes LC migration from sentinel tissues. Myeloid differentiation primary response 88 (MyD88), downstream of the IL-1 receptor, has functions in both RAS signaling and inflammation, leading to human cell transformation. In 2010, an activating mutation in the B-rapidly accelerated fibrosarcoma gene (BRAF) V600E was found in LCH. This BRAF mutation induces phosphorylation of the extracellular signal-regulated kinase (ERK) that may play an important role with MyD88 in LCH pathogenesis. However, phosphorylated ERK (pERK) is rapidly dephosphorylated by dual specificity phosphatase 6 (DUSP6), and limited proliferation is predicted in BRAF mutant cells. MyD88 binds pERK via its D-domain, thereby preventing pERK-DUSP6 interaction and maintaining ERK in an active, phosphorylated state. We detected MCPyV-DNA in the peripheral blood cells of two out of three patients with LCH in high-risk organs but not in those of patients with LCH in non-high-risk organs (0/12; P = .029). MCPyV infection can trigger precursor LCH cells with BRAF mutation to produce IL-1; the IL-1 loop is amplified in all LCH subclasses. Our model indicates both BRAF mutation and IL-1 loop regulation as potential therapeutic targets.

Multifocal Langerhans cell histiocytosis in an adult with a pathological fracture of the mandible and spontaneous malunion: A case report

Langerhans cell histiocytosis (LCH) is rare in the adult population and even rarer with jaw involvement. The current study presents the case of a 39-year-old male who complained of recurrent pain, swelling of the gingiva and an occasional pus-like discharge in the right mandible for one year. The patient was previously prescribed antibiotics, but this did not resolve the problem. An initial panoramic radiograph showed an osteolytic lesion and bone fracture in the right mandible. Eight months later, a new radiograph showed the spontaneous malunion of the fractured mandible. The patient was eventually diagnosed with Langerhans cell histiocytosis by histopathology and immunohistochemistry. Further lesions were found in the ribs and ilium by nuclear bone scanning. The patient was subsequently treated with systemic chemotherapy, and the lesions are currently effectively being controlled. This study is the first to show that spontaneous intralesional bone regeneration may lead to reunification of the mandible fracture caused by LCH in an adult.

Recurrent adult-onset hypophyseal Langerhans cell histiocytosis after radiotherapy: a case report

Introduction

Langerhans cell histiocytosis is a rare disease within the adult population, with very few cases reported as solitary hypophyseal lesions in adults. Of the reported cases, most have been treated successfully with surgery, radiotherapy, and/or chemotherapy. Radiotherapy has been thought to be curative at the relatively low dose of 20Gy. Here we report a case of recurrent hypophyseal Langerhans cell histiocytosis 9 months after radiotherapy with an interval period of symptomatic and radiographic response to therapy.

Case presentation

A 50-year-old Caucasian woman who had headaches, memory difficulties, and diabetes insipidus was found to have a 2.5cm suprasellar mass. Langerhans cell histiocytosis was diagnosed following stereotactic brain biopsy. Further workup revealed no other lesions. Initial radiation treatment succeeded in shrinking the tumor and relieving clinical symptoms temporarily; however, growth and recurrence of clinical symptoms was noted at 9 months. Re-irradiation was well tolerated and the patient had no acute side effects.

Conclusion

Isolated hypophyseal involvement by Langerhans cell histiocytosis in adults is a unique presentation of a rare disease. Although radiotherapy doses as low as 20Gy have been reported to offer control, this case demonstrates that higher doses may be warranted to ensure tumor control. With modern imaging and radiotherapy techniques higher doses should offer little increased more durable risk to surrounding critical structures.

Langerhans cell histiocytosis in a 5-month-old presenting with biparietal masses

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder that occurs most commonly in the pediatric population as a result of pathological clonal proliferation of Langerhans cells with subsequent damage and destruction to surrounding tissue. Clinically, LCH presents in a variety of ways, which often results in prolonged time to diagnosis and subsequently poorer outcomes. In this case report, the authors describe an unusually early presentation of multisystem LCH in a patient at birth, which resulted in a 5-month delay to diagnosis and treatment. This patient presented both atypically young and with an uncommon initial manifestation of multisystem disease with multiple soft-tissue swellings rather than early skin involvement. Additionally, this patient had an unusual radiographic appearance with biparietal skull destruction on initial skull radiographs and biparietal soft-tissue lesions on CT resembling cephalohematoma at 3 months of age. The clinical and radiological evaluation, pathology, and treatment strategies are discussed, with particular attention paid to the importance of further workup of atypical nonresolving cephalohematomas to prevent disease progression and poorer outcomes.

Langerhans cell histiocytosis: two case reports in adults and review of the literature

Langerhans Cell histiocytosis is a rare proliferative histiocytic disorder in which pathologic Langerhans cells accumulate in a variety of organs. The clinical presentation, evolution and therapeutic options are highly variable. Because of its relative rarity and the broad clinical spectrum, the diagnosis of Langerhans cell histiocytosis is often delayed or missed. At present, many questions with respect to aetiology, pathogenesis and treatment remain unanswered. In the present article we want to raise the awareness of this rare disease in adults and its diversity by the means of two case reports. In addition, the clinical manifestations, diagnosis and the current management are reviewed.

Long-term treatment of Langerhans cell histiocytosis of the mandibular condyle with indomethacin

Langerhans cell histiocytosis (LCH) most commonly occurs as a localized solitary bone lesion and appears predominantly in pediatric patients. LCH is characterized by the proliferation and accumulation of Langerhans cells which may cause pain and adjacent soft-tissue swelling. This disease is of clinical importance to dental professionals because LCH commonly involves the oral and maxillofacial region and early symptoms can be manifested in the jaw and, when overlooked, may result in extensive destruction of the involved structures. Considering the fact that this is a relatively rare entity, close investigation of the cases that are encountered are warranted. Herein we report a case of LCH occurring in the left condyle of an 11-year-old boy that initially showed clinical symptoms mimicking an abscess of the temporomandibular joint. The clinical and radiographic features, differential diagnosis, treatment, and long-term follow-up of this patient with indomethacin are presented.

Immunocytochemical investigation of Langerin (CD207) is a valuable adjunct in the cytological diagnosis of Langerhans cell histiocytosis of the thyroid

Langerhans cell histiocytosis (LCH) is an uncommon disease encompassing three clinically different entities: eosinophilic granuloma, Hand-Schüller-Christian disease, and Abt-Letterer-Siewe disease. Despite usually being a multisystemic disease affecting numerous different organs, involvement of the thyroid gland is extremely rare, and only a few cases in adults have been described in the literature. Herein, we present the case of a 28-year-old male patient presenting with LCH involving the skin, the skeletal system, and the thyroid gland. Fine needle aspiration (FNA) of the thyroid was performed and showed the typical Langerhans cells (LC) with foamy cytoplasm and slender nuclei with longitudinal grooves against a background of inflammatory cells with only a few eosinophilic granulocytes. Immunocytochemically, the LC showed positive staining with antibodies against CD1a and Langerin, a recently detected glycoprotein exclusively expressed in LC. Langerin is the major protein that makes up the so-called Birbeck granules, the electronmicroscopical hallmark of LC. Since LCH involvement of the thyroid is occasionally mistaken for papillary thyroid carcinoma cells, we propose that application of Langerin in combination with CD1a is a helpful diagnostic adjunct for the correct assessment of LCH affecting the thyroid gland.

[Clinical characteristics and survival of children with langerhans cell hystiocytosis]

INTRODUCTION

Langerhans cell histiocytosis is a rare disease in children, initial presentation is variable, clinical course, prognosis and survival are mostly unpredictable.

OBJECTIVE

To summarise clinical characteristics and treatment results in children with Langerhans cell histiocytosis.

METHOD

Retrospectively there were analysed patients with LCH diagnosed and treated at Haematology Department of University Children's Hospital in Belgrade from 1990 to 2006. Clinical presentation, therapy and survival according to Kaplan-Meier's statistical test was analysed.

RESULTS

30 patients were treated, aged from 4 months to 14 years, mean 3.9 years, median 2.3 years, 18 (60%) males, 12 (40%) females. A single system disease was diagnosed in 16 (53%) patients, of whom 6 patients with multifocal bone disease. All patients were in complete remission averagely following 162 and 82 months respectively. Multisystem disease was found in 14 (47%) patients. The lymph nodes and skin were more frequently involved organs than the central nervous system (diabetes insipidus), lung, liver and spleen. The number of involved organs ranged from 2 to 8, mean 4.2. Four patients died due to disease progression 3, 16, 36 and 66 months after diagnosis. Nine patents with multisystem disease were in remission with 117 months of follow-up. One patient was lost on follow-up.

CONCLUSION

The clinical course of patients with a single system disease is usually benign while a multisystem disease has to be aggressively treated with precise initial evaluation and staging before therapy.

Origin, homeostasis and function of Langerhans cells and other langerin-expressing dendritic cells

Langerhans cells (LCs) are a specialized subset of dendritic cells (DCs) that populate the epidermal layer of the skin. Langerin is a lectin that serves as a valuable marker for LCs in mice and humans. In recent years, new mouse models have led to the identification of other langerin(+) DC subsets that are not present in the epidermis, including a subset of DCs that is found in most non-lymphoid tissues. In this Review we describe new developments in the understanding of the biology of LCs and other langerin(+) DCs and discuss the challenges that remain in identifying the role of different DC subsets in tissue immunity.

Langerhans cell histiocytosis

The clinical manifestations of Langerhans cell histiocytosis have been recognized for more than a century. For most of that time, physicians have viewed the disease from different perspectives, interpreting portions of its clinical spectrum as if they were distinct and unrelated entities. More recently, Langerhans cell histiocytosis has been unified into a single concept, though the disease continues to defy traditional classification. By most accounts, Langerhans cell histiocytosis appears to be a morphologically benign proliferation of inflammatory cells that escapes regulatory control mechanisms. Studies from patients with all stages of the disease, however, document clonal proliferation of immune processing cells (i.e., Langerhans cells), suggesting a malignant disease process. The most common ophthalmic manifestation of Langerhans cell histiocytosis is a solitary lesion of orbital bone, which typically responds to minimally invasive therapy. The best management of solitary orbital Langerhans cell histiocytosis is debatable and has been complicated by its recent designation as a risk factor for central nervous system disease. This article summarizes recent developments in understanding the biology of Langerhans cell histiocytosis, reviews its ophthalmic manifestations, prognosis, and the controversy surrounding treatment of isolated orbital disease.

Langerhans cell histiocytosis of the thyroid gland

OBJECTIVES

A case is reported in which Langerhans cell histiocytosis was found in the thyroid gland. Although the thyroid gland is frequently affected with multiple common diseases, a search of the English language literature suggests that Langerhans cell histiocytosis in the thyroid gland is rarely reported.

STUDY DESIGN

The study design was of a case report and literature review.

SETTING

Academic tertiary referral practice.

METHODS

A case was reported, and the literature was reviewed.

RESULTS

A 31-year-old woman presented with an enlarged, diffusely firm, nontender, nonmobile, and not particularly nodular thyroid gland with mild compressive symptoms. She had intermittent skin papules and 1 episode of gingival ulceration. Ultrasound showed diffusely, hypoechoic thyroid with dimensions of 36 x 20 x 16 mm on the right and 36 x 16 x 17 mm on the left. No distinct nodules were noted, and thyroid function test results were normal. Laboratory testing for autoimmune abnormalities of the thyroid was negative for antithyroid peroxidase, antiparietal cell, and anti-smooth muscle cell antibodies. She tested positive for serum antithyroglobulin antibodies. A computed tomographic scan demonstrated abnormal low attenuation of her thyroid gland without any distinct nodules or masses. A fine-needle aspiration and core biopsy confirmed the diagnosis of Langerhans cell histocytosis. Dissection was technically challenging because of the firm and nonmobile lobes. Densely adherent strap musculature was encountered bilaterally, and the rare presence of a nonrecurrent laryngeal nerve was noted on the right. Histologically, thyroid parenchyma was largely obliterated by a diffuse infiltrate of mononuclear spindled to epithelioid histiocytes with few residual thyroid follicles. These histiocytes had moderate to abundant pale to eosinophilic cytoplasm, and some had prominent nuclear grooves and indentation/clefts, consistent with Langerhans histiocytes. Plasma cells and lymphocytes were sparsely dispersed. Immunohistochemistry showed that these histiocytes were positive for S-100, and rare lesional histiocytes were also positive for CD1a. Eosinophils were not readily identified in this lesion.

CONCLUSIONS

Langerhans cell histiocytosis in the thyroid gland is a rarely reported disease, with controversy over its management. This disease should be considered in the differential diagnosis of a diffusely irregular and firm thyroid gland, and multidisciplinary team cooperation is important for its diagnosis and management.

In vivo transformation of mouse conventional CD8alpha+ dendritic cells leads to progressive multisystem histiocytosis

Division and proliferation of dendritic cells (DCs) have been proposed to contribute to homeostasis and to prolonged antigen presentation. Whether abnormal proliferation of dendritic cells causes Langerhans cell histiocytosis (LCH) is a highly debated topic. Transgenic expression of simian virus 40 (SV40) T antigens in mature DCs allowed their transformation in vivo while maintaining their phenotype, function, and maturation capacity. The transformed cells were differentiated splenic CD8 alpha-positive conventional dendritic cells with increased Langerin expression. Their selective transformation was correlated with higher steady-state cycling compared with CD8 alpha-negative DCs in wild-type and transgenic mice. Mice developed a DC disease involving the spleen, liver, bone marrow, thymus, and mesenteric lymph node. Surprisingly, lesions displayed key immunohistologic features of Langerhans cell histiocytosis, including expression of Langerin and absence of the abnormal mitoses observed in Langerhans cell sarcomas. Our results demonstrate that a transgenic mouse model with striking similarities to aggressive forms of multisystem histiocytosis, such as the Letterer-Siwe syndrome, can be obtained by transformation of conventional DCs. These findings suggest that conventional DCs may cause some human multisystem LCH. They can reveal shared molecular pathways for human histiocytosis between humans and mice.

Systemic and endocrine manifestations of Langerhans' cell histiocytosis: current concepts in diagnosis and management

Langerhans' cell histiocytosis (LCH) is a rare disease of unknown etiology and variable biologic behavior and course. Almost every organ can be affected; however, it frequently involves the bones, lungs, skin and lymph nodes. LCH exhibits a particular predilection for involvement of the hypothalamo-pituitary axis resulting in diabetes insipidus and/or other anterior pituitary deficiencies. Although LCH can sometimes resolve spontaneously, it usually follows a chronic course and systemic treatment is mandatory for the management of multisystem disease. However, a significant number of patients will develop at least one permanent sequela as a consequence of the disease, with diabetes insipidus being the most common. A multidisciplinary approach is always needed in diagnosis, treatment and follow-up of all patients with LCH.

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a complex disease entity comprised of three distinct clinical syndromes that demonstrate indistinguishable histology. These syndromes are: eosinophilic granuloma, which is predominantly osseous or pulmonary; Hand-Schûller-Christian's disease, which involves multiple organ systems and, most typically, the skull base; and Letterer-Siwe's disease, the most severe disease manifestation, which typically involves the abdominal viscera. This article reviews our current understanding of Langerhans cell histiocytosis by discussing the history, histology, etiology, and treatment of the disease. It focuses on the radiographic findings and imaging modalities that are the most useful in disease diagnosis and management.

Recovery of cognitive function in neuropsychiatric Langerhan's cell histiocytosis

Langerhan's cell histiocytosis (LCH) has been described as a progressive neurological disorder marked by neurological and cognitive decline. The authors here report a case of a childhood LCH sufferer who made a significant recovery of neuropsychological function in the absence of motor recovery in late adolescence. This differential recovery of motor and cognitive functioning may relate to the interaction between LCH and childhood and adolescent neurodevelopmental processes.

Langerhans cell histiocytosis: current insights in a molecular age with emphasis on clinical oral and maxillofacial pathology practice

Langerhans cell histiocytosis (LCH) commonly involves the oral and maxillofacial region, and comes to the attention of dental practitioners when a patient presents with orofacial pain and a bony or soft tissue lesion. This is a relatively rare entity, which has made it difficult to investigate the clinical, biologic, and molecular aspects of the disease. Treatment protocols are not well defined, particularly in adults. During the past decade, the Histiocyte Society has formulated various LCH categories, based on risk stratification, and treatment protocols for the pediatric population. Adult trials are currently available through the Histiocyte Society. Although there has been considerable controversy, the neoplastic nature of LCH has been established by demonstrating clonality. LCH symptoms and the development and persistence of LCH lesions have been ascribed to a "chemokine/cytokine storm" due to autocrine and paracrine mechanisms. Discovery of biologic, cytogenetic, and molecular abnormalities in LCH have already affected treatment by providing novel therapeutic targets.

Biology of Langerhans cells and Langerhans cell histiocytosis

Langerhans cells (LC) are epidermal dendritic cells (DC). They play an important role in the initiation of immune responses through antigen uptake, processing, and presentation to T cells. Langerhans cell histiocytosis (LCH) is a rare disease in which accumulation of cells with LC characteristics (LCH cells) occur. LCH lesions are further characterized by the presence of other cell types, such as T cells, multinucleated giant cells (MGC), macrophages (MPhi), eosinophils, stromal cells, and natural killer cells (NK cells). Much has been learned about the pathophysiology of LCH by studying properties of these different cells and their interaction with each other through cytokines/chemokines. In this review we discuss the properties and interactions of the different cells involved in LCH pathophysiology with the hope of better understanding this enigmatic disorder.

Solitary Langerhans cell histiocytosis of the sternum in a 6-year-old girl: how should it be treated?

We report a 6-year-old girl with Langerhans cell histiocytosis (LCH) of the sternum successfully managed with intralesional methylprednisolone. Sternal LCH is a rare condition with only 8 cases published to date. Management has included partial sternectomy, radiotherapy, and chemotherapy. Recent literature regarding the solitary osseous focus of LCH supports conservative management with excellent outcome after intralesional steroid administration and reports of spontaneous resolution of disease. We advocate that conservative management should also be applied to LCH of the sternum.

Langerhans-cell histiocytosis: a clinical case without bone involvement

BACKGROUND

Langerhans-cell histiocytosis (LCH) is a group of rare disorders histologically characterized by the proliferation of Langerhans cells. Multiple organs and systems may be involved by the disease. Typically, there is bone involvement and, less frequently, lesions may be found in the lungs, liver, lymph nodes, skin, and mucosae. Oral soft tissue lesions without bone involvement are rare.

METHODS

We report a case of a 23-year-old man with LCH detected by oral soft tissue, cutaneous, and lung lesions.

RESULTS

Due to the oral lesion diagnosis, important procedures were performed, which determined the staging of the disease.

CONCLUSION

Gingival lesions could be one of the first manifestations of LCH. The periodontist should recognize and detect this important pathology with oral involvement.

Histiocitosis de células de Langerhans

Histiocytoses originate from the proliferation of mononuclear phagocytes in different tissues. These entities make up a heterogeneous group, and are mainly classified as Langerhans cell histiocytoses and non-Langerhans cell histiocytoses. Langerhans cell histiocytoses have as a common characteristic the proliferation of dendritic antigen-presenting cells with phenotypical and ultrastructural characteristics of Langerhans cells. Infiltration may be limited to one organ, or may be disseminated. The prognosis and the treatment especially depend on the age of the patient and the number and dysfunction of the organs involved. Its etiopathogenesis is unknown, although most researchers currently believe that an alteration in the regulation of the immunological system occurs in these patients.

Isolated vulvar Langerhans cell histiocytosis: report of two cases

Two cases of Langerhans cell histiocytosis involving the vulva are reported. The clinical features of Case 1 have been previously reported. The patients, aged 31 (Case 1) and 52 (Case 2) years, had disease limited to the vulva at the time of diagnosis. In both cases, the vulvar lesions were composed of Langerhans cells with twisted nuclei and nuclear grooves, associated with eosinophils and other inflammatory cells. Immunohistochemical studies using fixed, paraffin-embedded tissue sections showed that the Langerhans cells were positive for CD1A and S-100 protein in both cases, supporting the morphologic diagnosis. The first patient had multiple local recurrences during 3 years despite radiation therapy and vulvectomy, but is currently in remission and being treated with thalidomide. The second patient experienced disseminated disease involving multiple bony sites and the mouth despite radiation therapy. Including the present two cases, 6 of 18 (33%) cases of isolated vulvar LCH subsequently disseminated, most commonly to bone; other patients had local recurrences. Thus isolated vulvar LCH has the potential for aggressive clinical behavior, either as local recurrence or disseminated disease. New treatment modalities are needed for this disease.

Langerhans cells - dendritic cells of the epidermis

Langerhans cells (LC) are dendritic cells of the epidermis. They are highly specialized leukocytes that serve immunogenic and tolerogenic purposes. Here, we review some aspects of LC biology, emphasizing those areas where LC are or may turn out to be special.

Pulmonary Langerhans cell histiocytosis: emerging concepts in pathobiology, radiology, and clinical evolution of disease

Pulmonary Langerhans cell histiocytosis (PLCH) is an uncommon disorder of adult smokers associated with a significant morbidity. Arising from the aberrant accumulation of Langerhans and other immune cells, PLCH tends to cause a relatively isolated pulmonary involvement as compared to other forms of Langerhans cell (LC) and histiocytic disorders. Increased knowledge of cytokine triggers, dendritic cell trafficking, and clonality of LC populations in PLCH have resulted in an improved understanding of the pathobiology of PLCH. High-resolution CT (HRCT) of the chest has led to better appreciation of nodular and cystic radiographic abnormalities characteristic of the disease. Correlation of HRCT abnormalities with lung pathologic changes has led to an improved comprehension of clinical evolution of PLCH. Current clinical predictors for PLCH outcomes remain poor, although long-term follow-up and radiologic monitoring may help to define disease progression. This review discusses advances in PLCH emphasizing the etiopathologic bases of the disease and currently available radiologic modalities for monitoring disease progression.