Langerhans cell histiocytosis and juvenile xanthogranuloma. Two case reports

Synchronous Pulmonary Langerhans Cell Histiocytosis and Multiple Cutaneous Reticulohistiocytomas With a Common BRAF- V600E/D Mutation Driver

ABSTRACT

Histiocytoses constitute a group of heterogeneous disorders characterized by involvement of variable organs by neoplastic macrophage or dendritic cells. They may affect both adults and children with a predilection to the skin, bone, lungs, lymph nodes, and CNS. The coexistence of different types of histiocytoses in the same patient is an extremely rare phenomenon. We describe a very rare case of co-occurring pulmonary Langerhans cell histiocytosis with multiple cutaneous reticulohistiocytomas with a common BRAF- V600E mutation as the driver genetic event in both the lung and skin lesions. The presence of a common BRAF- V600E mutation provides evidence of their clonal relation and contributes to our understanding in the pathogenesis of multiple, co-occurring histiocytic proliferations.

Orbital histiocytosis; From A to Z

PURPOSE

Histiocytosis is one of the most challenging diseases in medical practice. Because of the broad spectrum of clinical manifestations, systemic involvements, unknown etiology, and complex management, different types of histiocytosis are still a big question mark for us. Orbital histiocytosis is characterized by the abnormal proliferation of histiocytes in orbital tissues. It could affect the orbit, eyelid, conjunctiva, and uveal tract. Orbital histiocytosis can cause limited eye movement, proptosis, decreased visual acuity, and epiphora. In this study, we review the novel findings regarding the pathophysiology, diagnosis, and treatment of different types of histiocytosis, focusing on their orbital manifestations.

METHOD

This review was performed based on a search of the PubMed, Scopus, and Embase databases or relevant published papers regarding orbital histiocytosis on October 9th, 2023. No time restriction was proposed, and articles were excluded if they were not referenced in English.

RESULTS

391 articles were screened, most of them being case reports. The pathophysiology of histiocytosis is still unclear. However, different mutations are found to be prevalent in most of the patients. The diagnostic path can be different based on various factors such as age, lesion site, type of histiocytosis, and the stage of the disease. Some modalities, such as corticosteroids and surgery, are used widely for treatment. On the other hand, based on some specific etiological factors for each type, alternative treatments have been proposed.

CONCLUSION

Significant progress has been made in the detection of somatic molecular changes. Many case studies describe various disease patterns influencing the biological perspectives on different types of histiocytosis. It is necessary to continue investigating and clustering data from a broad range of patients with histiocytosis in children and adults to define the best ways to diagnose and treat these patients.

Langerhans Cell Histiocytosis Evolving into Juvenile Xanthogranuloma: Two Linked Entities

BACKGROUND

Langerhans cell histiocytosis (LCH) represents a myeloid clonal proliferation that involves the skin and other organs. Occasionally, cases of LCH evolve into juvenile xanthogranuloma (JXG).

CASE PRESENTATION

A 7-month-old boy presented with an itchy, flaky rash resembling seborrheic dermatitis affecting the scalp and eyebrows. The lesions started at 2 months old. On physical examination, there were reddish/brown lesions on the trunk, denuded areas on the groin and neck, and a large lesion behind his bottom teeth. In addition, there were thick white plaques in his mouth and thick whitish material in both ears. A skin biopsy showed features of LCH. Radiologic examination demonstrated several osteolytic lesions. Chemotherapy produced marked improvement. A few months later, the patient developed lesions with clinical and histologic features of XG.

CONCLUSION

A possible association between LCH and XG is explained by lineage maturation development. Chemotherapy may play a role in modifying the production of cytokines that enhance the transformation or 'maturation' of Langerhans cells into multinucleated macrophages (Touton cells) characteristic of a more favorable proliferative inflammatory condition.

Neuroimaging in Pediatric Patients with Juvenile Xanthogranuloma of the CNS

BACKGROUND AND PURPOSE

Juvenile xanthogranuloma is a rare clonal, myeloid, neoplastic disorder. Typically, juvenile xanthogranuloma is a self-limited disorder of infancy, often presenting as a solitary red-brown or yellow skin papule/nodule. A small subset of patients present with extracutaneous, systemic juvenile xanthogranuloma, which may include the CNS. The goal of this retrospective study was to evaluate and categorize the neuroimaging findings in a representative cohort of pediatric patients with CNS juvenile xanthogranuloma.

MATERIALS AND METHODS

The brain and/or spine MR imaging data of 14 pediatric patients with pathology-proven juvenile xanthogranuloma were categorized and evaluated for the location; the signal intensity of xanthogranulomas on T1WI, T2WI, DWI, and a matching ADC map for the pattern and degree of contrast enhancement; and the presence of perilesional edema, cysts, or necrosis.

RESULTS

Fourteen pediatric patients (8 girls, 6 boys; mean age, 84 months) were included in the study. Patients presented with a wide variety of different symptoms, including headache, seizure, ataxia, strabismus, hearing loss, facial paresis, and diabetes insipidus. Juvenile xanthogranuloma lesions were identified in a number of different sites, including supra- and infratentorial as well as intracranial and spinal leptomeningeal. Five patients were categorized into the neuroradiologic pattern unifocal CNS juvenile xanthogranuloma; 8, into multifocal CNS juvenile xanthogranuloma; and 1, into multifocal CNS juvenile xanthogranuloma with intracranial and spinal leptomeningeal disease. In most cases, xanthogranulomas were small-to-medium intra-axial masses with isointense signal on T1WI (compared with cortical GM), iso- or hyperintense signal on T2WI, had restricted diffusion and perilesional edema. Almost all xanthogranulomas showed avid contrast enhancement. However, we also identified less common patterns with large lesions, nonenhancing lesions, or leptomeningeal disease. Four cases had an additional CT available. On CT, all xanthogranulomas were homogeneously hyperdense (solid component) without evident calcifications.

CONCLUSIONS

CNS juvenile xanthogranuloma may demonstrate heterogeneous neuroimaging appearances potentially mimicking other diseases, such as primary brain neoplasms, metastatic disease, lymphoma and leukemia, other histiocytic disorders, infections, or granulomatous diseases.

International expert consensus recommendations for the diagnosis and treatment of Langerhans cell histiocytosis in adults

Langerhans cell histiocytosis (LCH) can affect children and adults with a wide variety of clinical manifestations, including unifocal, single-system multifocal, single-system pulmonary (smoking-associated), or multisystem disease. The existing paradigms in the management of LCH in adults are mostly derived from the pediatric literature. Over the last decade, the discovery of clonality and MAPK-ERK pathway mutations in most cases led to the recognition of LCH as a hematopoietic neoplasm, opening the doors for treatment with targeted therapies. These advances have necessitated an update of the existing recommendations for the diagnosis and treatment of LCH in adults. This document presents consensus recommendations that resulted from the discussions at the annual Histiocyte Society meeting in 2019, encompassing clinical features, classification, diagnostic criteria, treatment algorithm, and response assessment for adults with LCH. The recommendations favor the use of 18F-Fluorodeoxyglucose positron emission tomography-based imaging for staging and response assessment in the majority of cases. Most adults with unifocal disease may be cured by local therapies, while the first-line treatment for single-system pulmonary LCH remains smoking cessation. Among patients not amenable or unresponsive to these treatments and/or have multifocal and multisystem disease, systemic treatments are recommended. Preferred systemic treatments in adults with LCH include cladribine or cytarabine, with the emerging role of targeted (BRAF and MEK inhibitor) therapies. Despite documented responses to treatments, many patients struggle with a high symptom burden from pain, fatigue, and mood disorders that should be acknowledged and managed appropriately.

Juvenile xanthogranulomas in Asian children

Juvenile xanthogranuloma (JXG) is the most common non-Langerhans cell histiocytic disorder. It can rarely be associated with systemic involvement. There is a paucity of literature on JXG in Asian children. We aim to describe the epidemiology, clinical features, systemic associations, histological features and outcome of a cohort of Asian children with JXG, and review the literature on the condition. We retrospectively reviewed the demographic, clinical and histological data of patients less than 16 years of age, diagnosed with JXG at our tertiary pediatric hospital between January 2002 and April 2019. A total of 147 children with JXG were identified, with a slight male preponderance of 53.1%. The median age of the onset was 15.5 months, with 69.4% presenting before 2 years of age. There was no racial predilection. The most frequently involved site was the head and neck region (44.2%). The majority of patients (76.2%) presented with a solitary lesion. Spontaneous resolution was documented in 57.7% of our patients with mean duration to resolution of 18.8 months. The proportion and speed of resolution did not differ in children with single or multiple lesions. No ophthalmologic complications were detected in our study cohort. JXG in children is generally limited to the skin and is rarely associated with systemic involvement, including the eye. Unless clinically indicated, the results from our study does not support routine screening for juvenile myelomonocytic leukemia, eye or systemic complications, even in the setting of multiple cutaneous JXGs.

The triptych of mixed histiocytosis: a systematic review of 105 cases and proposed clinical classification

Histiocytoses are one of the ultimate diagnostic challenges that every physician face at least once in his/her life. Giving their protean manifestation and differentiated therapeutic needs, histiocytosis requires extensive characterization and multidisciplinary management. Mixed histiocytosis is an emerging group of syndromes defined by the overlap of Langerhans cell histiocytosis and another histiocytic disorder of different type. Despite rare, it may account for up to a fifth of systemic histiocytosis patients in some series. In this work, we comprehensively review for the first time the clinical, radiological, histopathological and molecular features of mixed histiocytosis in children and adults. Moreover, we propose a clinical classification in three groups that differentiate patients with systemic involvement and worse overall survival to other groups with more localized manifestations and indolent behavior, wanting to ease their recognition and treatment. Interestingly we also found that mixed histiocytosis harbor BRAFV600E mutations with a higher frequency comparing to all other histiocytoses, and may therefore benefit of specific inhibitory drugs.

Aggressive surgical management of recurrent intracranial juvenile xanthogranuloma: case report and review of the literature

INTRODUCTION

Juvenile xanthogranuloma (JXG) with the central nervous system (CNS) involvement is a rare disease entity that remains poorly understood, especially when the condition develops following treatment for Langerhans cell histiocytosis (LCH).

CASE REPORT

A 21-year-old man who was diagnosed with LCH at age 2, several years following which he developed signs and symptoms of CNS involvement. Magnetic resonance imaging (MRI) of the brain revealed JXG with bilateral choroid plexus involvement. As radiation therapy for the intraventricular masses proved unsuccessful, he underwent two surgical resections. In the following years, he developed another large JXG in the meninges, which was managed conservatively until he required surgery due to symptom progression. Twelve years after the first surgery, the patient is in stable condition with no evidence of recurrence.

CONCLUSION

Due to the rarity of JXG in the CNS, optimal treatment strategies and the precise duration of therapy remain to be determined. Future studies should aim to develop an appropriate treatment algorithm for such rare cases.

Rare childhood hybrid histiocytosis of the central nervous system-diagnosed by stereotactic brain biopsy with marked treatment response to clofarabine

Histiocytosis is a heterogeneous group of disease entities, comprised by two main categories, namely Langerhans and non-Langerhans cell histiocytoses. Central nervous system involvement in histiocytosis is considered very rare and is often secondary to affection of anatomically related bone structures and/or multi-organ disease. We present a never-before described case of rare childhood histiocytosis with hybrid features of Langerhans cell histiocytosis and juvenile xanthogranuloma confined to the central nervous system in a 2- and a half-year-old boy with distinct treatment response to clofarabine. The case also emphasizes the diagnostic significance of stereotactic brain biopsy.

Rosai-Dorfman disease as a rare cause of cervical lymphadenopathy - case report and literature review

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare, benign clinical entity of unknown cause. RDD is characterised by the overproduction and accumulation of histiocytes, primarily in the lymph nodes, although it may affect every organ and system. It predominantly affects children and young adults. Typically, patients are in good general condition, with massive cervical lymphadenopathy and fever. In about 40% of cases extranodal localisation of RDD is diagnosed. In laboratory tests the most common abnormalities are increased erythrocyte sedimentation rate (ESR), leukocytosis with neutrophilia, normocytic anaemia, and hypergammaglobulinaemia. Histopathological examination remains the mainstay of diagnosis - lymph nodes have massive sinusoidal dilation, containing histiocytes positive for S-100 and CD68, and negative for CD1a. Most patients do not require treatment as spontaneous remissions are observed. We present a brief review of the literature and the case of a six-year-old boy with cervical lymphadenopathy diagnosed with RDD. So far, the patient has not required systemic treatment and has been kept under observation.

Disseminated juvenile xanthogranuloma occurring after treatment of Langerhans cell histiocytosis: a case report

CASE PRESENTATION

An 11-year-old boy presented with a complaint of a painful temporal mass. Brain magnetic resonance imaging (MRI) showed a 3-cm-sized, homogeneously enhancing mass in the greater wing of the left sphenoid bone, which was diagnosed as Langerhans cell histiocytosis (LCH). Chemotherapy with vincristine and prednisolone was performed for 1 year. After 1 year and 11 months off treatment, he developed symptoms such as polydipsia and polyuria. Brain MRI showed thickening of the pituitary stalk with enhancement, suggestive of LCH involvement, and no recurrence in the sphenoid bone. After 4 years and 4 months off treatment, he developed multiple, subcutaneous, asymptomatic, and yellowish variable-sized papules on his face, posterior neck, and back, which were pathologically diagnosed as juvenile xanthogranuloma (JXG). Brain MRI revealed multifocal enhancing skull lesions in the left parietal, right frontal, and left occipital bones, which were also diagnosed as JXG. After 5 years and 8 months off treatment, the number of variable-sized skin lesions was increased without changes in the lesions in the skull and pituitary stalk.

CONCLUSION

We report a case of disseminated JXG occurring after treatment of LCH. These clinical co-presentations suggested a close relationship between their pathogenesis.

Juvenile Xanthogranuloma in a Pediatric Patient with Langerhans Cell Histiocytosis

Purpose

To report a case of juvenile xanthogranuloma that simulated a chalazion and to discuss the association between juvenile xanthogranuloma and Langerhans cell histiocytosis.

Method

Case report and review of literature.

Results

A 13-year-old boy with a prior history of Langerhans cell histiocytosis was referred to our clinic for a possible chalazion. The patient had undergone treatment for Langerhans cell histiocytosis 10 years prior. The patient underwent an excisional biopsy. Histopathology revealed a proliferation of histiocytes and lymphocytes with Touton giant cells, consistent with a diagnosis of juvenile xanthogranuloma.

Conclusions

Though the relationship between Langerhans cell histiocytosis and juvenile xanthogranuloma has yet to be fully elucidated, juvenile xanthogranuloma should be included in the differential diagnosis for any former Langerhans cell histiocytosis patient presenting with a new cutaneous lesion.

Bone pathologic fracture revealing an unusual association: coexistence of Langerhans cell histiocytosis with Rosai-Dorfman disease

Background

The coexistence of Rosai-Dorfman disease (RDD) with Langerhans cell histiocytosis (LCH) is very rare, as to date only 17 cases have been reported in the english literature. The pathophysiology of this uncommon co-occurrence still remains enigmatic and a subject of various speculations.

Case presentation

We report a case of a 30-year-old female patient who presented with a pathologic fracture of the left proximal femur. Her medical history was unremarkable, there were no fever, skin lesions, lymphadenopathy or other organomegaly at physical examination. X-ray radiograph of the fractured femur showed an isolated and ill-defined osteolytic lesion. The histopathological analysis of biopsies from this lesion were consistent with a combined RDD-LCH of the bone.

Conclusion

Combined RDD-LCH is a very rare phenomenon, whose pathophysiology still remains unclear and a subject of various speculations.

Progress in understanding the pathogenesis of Langerhans cell histiocytosis: back to Histiocytosis X?

Langerhans cell histiocytosis (LCH), the most common histiocytic disorder, is characterized by the accumulation of CD1A(+) /CD207(+) mononuclear phagocytes within granulomatous lesions that can affect nearly all organ systems. Historically, LCH has been presumed to arise from transformed or pathologically activated epidermal dendritic cells called Langerhans cells. However, new evidence supports a model in which LCH occurs as a consequence of a misguided differentiation programme of myeloid dendritic cell precursors. Genetic, molecular and functional data implicate activation of the ERK signalling pathway at critical stages in myeloid differentiation as an essential and universal driver of LCH pathology. Based on these findings, we propose that LCH should be re-defined as an inflammatory myeloid neoplasia. Increased understanding of LCH pathogenesis will provide opportunities to optimize and personalize therapy through improved risk-stratification, targeted therapy and assessment of therapy response based on specific molecular features and origin of the pathological myeloid cells.

Multicentric reticulohistiocytosis and fibroblastic rheumatism

Multicentric reticulohistiocytosis (MRH) and fibroblastic rheumatism (FR) are uncommon disorders with similar joint and skin manifestations. They are usually included among the non-Langerhans histiocytoses, but recent insights drive some criticism. The diagnosis is often challenging and must be confirmed by the histological typical features. If the skin manifestations are missing, the arthritic complaints may be confused with those of other rheumatic disorders. In these cases, only a careful clinical and radiological evaluation leads to the correct diagnosis. The natural course of the diseases may rapidly develop into disabling manifestations, making an aggressive treatment strongly recommendable. There is emerging evidence that anti-tumour necrosis factor-α agents and bisphosphonates are promising drugs for MRH, while a course of methotrexate and steroids seems to be the best option for FR. Finally, the clinician should be aware that in many cases MRH, but not FR, is associated with a large number of systemic manifestations and with malignancy. This eventuality must be accurately ruled out.

Pathological consequence of misguided dendritic cell differentiation in histiocytic diseases

Histiocytic disorders represent a group of complex pathologies characterized by the accumulation of histiocytes, an old term for tissue-resident macrophages and dendritic cells. Langerhans cell histiocytosis is the most frequent of histiocytosis in humans and has been thought to arise from the abnormal accumulation of epidermal dendritic cells called Langerhans cells. In this chapter, we discuss the origin and differentiation of Langerhans cells and dendritic cells and present accumulated evidence that suggests that Langerhans cell histiocytosis does not result from abnormal Langerhans cell homeostasis but rather is a consequence of misguided differentiation programs of myeloid dendritic cell precursors. We propose reclassification of Langerhans cell histiocytosis, juvenile xanthogranuloma, and Erdheim-Chester disease as inflammatory myeloid neoplasias.

Langerhans cell histiocytosis preceding the development of juvenile xanthogranuloma: a case and review of recent developments

Langerhans cell histiocytosis (LCH) and juvenile xanthogranuloma (JXG) both belong to the histiocytosis group of disorders, which have varied prognostic and clinical significance. Their normal cellular counterparts share a common CD34-positive hematopoietic stem cell precursor that matures along CD14-negative or -positive pathways. Rare cases of LCH and JXG show overlapping findings, suggesting that this divergent maturation is not irreversible. We report a case of an infant diagnosed with cutaneous LCH shortly after birth. Two years after diagnosis, a recurrent lesion in his external auditory canal contained lipidized cells with CD68 and factor XIIIa expression and lacked Birbeck granules and CD1a, consistent with JXG. Our case and previous reports of this phenomenon raise the question of a histogenic relationship between LCH and JXG, and we speculate that the lesional cells of origin are subjected to therapy-induced modulation that results in a varied differentiation.

An aggressive systemic juvenile xanthogranuloma clonally related to a preceding T-cell acute lymphoblastic leukemia

Juvenile xanthogranuloma (JXG) is a disorder of disputed origin thought to be related to the dermal/interstitial macrophage. A 5-year-old female presented with an aggressive systemic JXG that developed 5 months after the diagnosis of T-cell acute lymphoblastic leukemia (T-ALL). Examination of the T-cell receptor gamma (TCR-γ) rearrangement in T-ALL blasts, JXG infiltrated lymph node biopsies and micro-dissected JXG histiocytes revealed an identical bi-allelic TCR-γ rearrangement in all samples, thus providing evidence for a clonal relationship between T-ALL and JXG in this case.

Solitary juvenile xanthogranuloma of the temporal muscle and bone penetrating the dura mater in a 2-month-old boy

Juvenile xanthogranuloma (JXG) is a rare histiocytic disorder primarily observed during the first 2 years of life. Most patients present with a solitary cutaneous lesion; however, others present with extracutaneous manifestations or even with systemic involvement. The authors describe a 2-month-old boy in whom was diagnosed a unifocal extracutaneous JXG involving the temporal bone. Unlike 3 other cases of solitary JXGs of the temporal bone in the literature, the present case involved destruction of the dura mater and leptomeningeal enhancement surrounding the entire temporal lobe. The lesion did not regress after an initial biopsy procedure and had to be removed more radically because of progressive mass effect on the brain. The child recently underwent a reconstructive skull procedure and is doing well almost 2 years postoperatively without evidence of disease. This case demonstrates that even in instances of extensive disease a favorable outcome is possible without chemotherapy.

Cutaneous normolipemic plane xanthoma with supraglottic involvement in a patient with hand-Schüller-Christian Disease: a case report

Normolipemic plane xanthoma (NPX) is a histiocytic disorder characterized by yellow-orange plaques in the periorbital areas, neck, upper trunk, and flexural folds. Association with systemic disease or paraproteinemia has been reported previously, but rarely with Langerhans cell histiocytosis (LCH). We report a case of Hand-Schüller-Christian disease (a type of LCH) in a patient who developed NPX with supraglottic involvement. NPX developed after several courses of chemotherapy and the supraglottic xanthoma occurred about 2 years later. The coexistence of LCH and non-LCH histiocytic lesions in this patient could be a result of chemotherapy-induced changes or may be just coincidental.

Diffuse xanthogranulomatous dermatitis and systemic Langerhans cell histiocytosis: A novel case that demonstrates bridging between non-Langerhans cell histiocytosis and Langerhans cell histiocytosis

The advent of electron microscopy and immunohistochemical stains allowed for reclassification of the histiocytoses based on the predominant cell in the infiltrate. Although the current schema simplicity provides a good foundation, some patients display overlapping clinical and immunohistochemical features that defy classification. The patient herein illustrates bridging between histiocytic disorders. Through this case we review the various conditions classified under the non-Langerhans cell histiocytosis and Langerhans cell histiocytosis rubric.

Treatment of juvenile xanthogranuloma

Juvenile xanthogranuloma (JXG) is generally a benign, self-limited histiocytic disorder of the skin. We report two cases of multisystem JXG presenting with clinical features more commonly seen in Langerhans cell histiocytosis (LCH), including diabetes insipidus and lytic bony lesions. Histologically, the skin lesions demonstrated a histiocytic dermal infiltrate that stained for CD-68, but S-100 and CD1a stains were negative. Treatment according to LCH-based chemotherapy regimens resulted in prompt resolution of symptoms. A literature review of multisystem JXG cases treated with chemotherapy suggests that symptomatic patients can successfully be treated with LCH-based regimens that include both corticosteroids and vinca alkaloids.

Disseminated xanthogranulomas associated with adult T-cell leukaemia/lymphoma: a case report and review the association of haematologic malignancies

Xanthogranuloma (XG) is rarely observed in adults and has been reported to be associated with chronic myelogenous leukaemia (CML) and/or neurofibromatosis type 1 (NF1). A 68-year-old woman with adult T-cell leukaemia/lymphoma (ATLL) gradually developed disseminated XGs over the 3 years since disease onset. Histopathological examination of a skin biopsy revealed the presence of histiocytes in the dermis with a few Touton giant cells admixed with lymphoid cells. The lesions of XGs persisted despite chemotherapy with prednisolone and chlorambucil for her ATLL. This is the first report of disseminated XGs associated with ATLL. The association of disseminated XGs with haematologic malignancies was reviewed and the possible pathogenesis of this association will be discussed.

[Juvenile multiple xanthogranuloma in a patient with Langerhans cell histiocytosis]

We present the case of a 10-week-old girl who had erythematous papules with a yellowish hue from birth with diagnosis of Langerhans cell histiocytosis, that was accompanied by a lytic lesion in the skull and hepatic involvement. After several months of treatment with prednisone and vinblastine with skin and systemic improvement, several rounded erythematous papules with a yellowish hue appeared in the right cheek. The biopsy showed a histiocytic infiltrate with positivity for CD68 and negative staining for S100 and CD1a, with a final diagnosis of juvenile xanthogranuloma. This association has been previously described in the literature in few cases. Although several hypotheses have been suggested, the causal relationship between both entities has still not been demonstrated.

Prolonged severe pancytopenia preceding the cutaneous lesions of juvenile xanthogranuloma

We report a case of juvenile xanthogranuloma (JXG) having progressive pancytopenia for 6 months until the proliferating skin lesions. A 2-month-old infant presented recurrent fever, anemia, and hepatosplenomegaly mimicking hemophagocytic lymphohistiocytosis (HLH) or juvenile myelomonocytic leukemia (JMML). At 8 months of age, the biopsy of a growing papule on the elbow made the diagnosis. Bone marrow (BM) specimens showed clustering foamy cells including hemophagocytosis by histiocytes. Treatment with etoposide followed by vinblastine plus prednisolone (PSL) therapy improved the disease. Although JXG is a benign non-Langerhans cell histiocytosis, the multisystem-visceral form should be considered as a potential aggressive disease when associated with BM failure in early infancy.

[Generalized eruptive histiocytoma]

We present the case of a 64-year-old male who developed multiple asymptomatic papules over a four-month period, distributed symmetrically on the trunk and proximal regions of the limbs, while the scalp, palms, soles and mucous membranes were spared. The lesions were discrete papules, brownish-erythematous, rounded, ranging from slightly raised to hemispherical, from 1 to 3 mm in diameter and firm to the touch. Clinical, histopathological, immunohistochemical and ultrastructural studies were consistent with generalized eruptive histiocytoma. Laboratory tests and radiological studies did not show any abnormal findings. After being subjected to photochemotherapy, the lesions regressed, but later on new outbreaks of papules appeared. Generalized eruptive histiocytoma belongs to a spectrum of diseases that may overlap; some may even develop into others. As the disease may progress into a more serious ailment, regular checkups with clinical, histological and immunohistochemical examinations should definitely be considered.

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.

Multiple Adult Xanthogranuloma: Case Report and Literature Review

BACKGROUND

Non-Langerhans cell histiocytoses form a heterogeneous group defined by the proliferation of cells with macrophage characteristics. Diagnosis is easy in typical cases but becomes more complex in unusual forms.

CASE REPORT

We report the case of a 53-year-old patient who presented multiple brown-to-yellowish papules and nodules of the trunk, neck, and head evolving for 6 months. No visceral involvement was found. Histopathological examination revealed histiocytic proliferation with features of secondary xanthomization with the presence of giant foamy multinucleated Touton cells. One year later, all lesions cleared spontaneously. Based on the clinical presentation and evolution and on the immunohistologic data, we retain the diagnosis of adult xanthogranuloma (AXG) in a diffuse shape.

DISCUSSION

Multiple AXG is a rare entity (15 cases reported since 1963) with a stereotypic presentation. It is important to recognize because of its good prognosis and the absence of visceral involvement therefore requiring no investigations or aggressive treatments. This case is interesting because of the complete and spontaneous healing of all the lesions within 20 months.