A case report of multicentric reticulohistiocytosis with atypical cutaneous presentation.

Multicentric reticulohistiocytosis (MRH) is a rare systemic disorder characterized by histiocytic hyperplasia that mainly involves the skin, mucous membranes, and joints. The typical clinical features include papules, nodules, and arthritis. MRH lesions are relatively extensive but small and scattered. Joint inflammation is characterized by diffuse symmetric polyarthritis as the first symptom, which can be severe and disabling due to destructive joint changes. MRH is easily misdiagnosed in clinical practice. Here, we report the case of an elderly male patient who presented with polyarticular pain in the hip and interphalangeal joints as the first manifestation, followed by the development of large, isolated, bulging skin nodules, which are atypical MRH lesions. This is rare in all MRH case reports, and we made the correct diagnosis by combining skin histopathology, immunohistochemistry, and other clinical examinations. We performed surgical treatment on the local skin lesions of this patient. This case suggests that clinicians should actively correlate the condition and accurately diagnose MRH when encountering atypical skin changes or other diseases as the first symptom and explore the mechanisms of MRH and other clinical manifestations.

Therapy of necrobiotic xanthogranuloma - case series and review of the literature.

Necrobiotic xanthogranuloma is a rare disease that is part of the non-Langerhans cell histiocytoses. It is characterized by yellowish skin lesions, which are typically periorbitally localized. Extracutaneous manifestations of all organs are possible and can cause potentially life-threatening complications. The disease also belongs to the facultative paraneoplasias and is often associated with paraproteinemia. These aspects should be considered regarding further diagnostics. Due to the rarity of the disease, there are no standardized guidelines for therapy so far. The combination of prednisolone and chlorambucil as well as intravenous immunoglobulins seem to be effective therapeutic options. We present four cases from our clinic as well as the current results of the literature in this mini-review and would like to highlight the therapeutic challenge as well as the need for the development of guidelines.

Utility of 18F-FDG PET/CT in Assessment of Disease Extent and Response to Treatment in Xanthoma Disseminatum.

The clinical utility of 18F-FDG PET/CT is being increasingly recognized in histiocytic disorders. We report the case of a 23-y-old woman who presented with slowly progressive, yellowish-brown papules, plaques, and nodules over her face and flexures. Besides the multiple cutaneous lesions, lesions of the brain, stomach, gallbladder, and marrow were additionally revealed by baseline 18F-FDG PET/CT. Skin biopsy and the overall clinical picture were consistent with xanthoma disseminatum. Subsequent PET/CT after cladribine therapy revealed a decrease in the extent and metabolic activity of most lesions, suggestive of a favorable response. This case report highlights the potential role of 18F-FDG PET/CT in the accurate assessment of disease extent and posttreatment response in rare histiocytic disorders.

Histiocitosi en pediatria: la gran simuladora / Histiocitosis en pediatría: la gran simuladora / Histiocytosis in pediatrics: the great simulator

Fonament. La histiocitosi de cèl·lules de Langerhans (HCL) és una malaltia caracteritzada per l’acumulació anormal decèl·lules del sistema monociticomacrofàgic, amb una presentació clínica molt variable. Sovint, atesa la gran variabilitat clínica d’aquesta entitat, es fan diagnòstics tardansque repercuteixen en el pronòstic.Objectiu. Descriure les principals manifestacions clíniquesde l’histiocitosi de cèl·lules de Langerhans (HCL) en unhospital de tercer nivell els darrers catorze anys. Mètode. Estudi observacional, descriptiu i retrospectiu delscasos d’HCL tractats a l’Hospital Universitari Vall d’Hebron.Criteris d’inclusió: edat dels participants (de 0 dies fins a 18anys), període d’estudi (2006-2021) i diagnòstic de la malaltia, basat en el diagnòstic clínic o la confirmació histològica. Mitjançant la revisió d’històries clíniques es van registrar variables demogràfiques (edat i sexe), clíniques (formade presentació, manifestacions inicials, evolució i recaigudes) i troballes rellevants en les proves complementàries. Resultats. Es van revisar 55 casos diagnosticats d’HCL. Lamitjana d’edat de presentació va ser 4,5 anys (RI 1-8), ambpredomini del sexe masculí (3:1). El motiu de consulta mésfreqüent ha estat l’aparició d’una tumoració (20%, sobretota la zona cranial), seguit per dolor ossi (14,5%), polidípsiai poliúria (9,1%), torticoli (9,1%), coixesa, exantema cutanii febre (7,3% cadascuna). Basant-nos en la classificacióLCH-IV, la majoria es van classificar com a unisistèmiques(71%) enfront de les multisistèmiques (29%). Conclusions. L’HCL és una malaltia poc freqüent en pediatria, però amb un espectre clínic ampli que comportadiagnòstics tardans associats a complicacions. Té molta importància conèixer aquesta entitat i les seves manifestacionsprincipals. (AU)

Fundamento. La histiocitosis de células de Langerhans (HCL) es una enfermedad caracterizada por la acumulación anormal de células del sistema monocítico-macrofágico, con una presentación clínica muy variable. A menudo, dada la gran variabilidad clínica de esta entidad, se realizan diagnósticos tardíos que repercuten ensu pronóstico. Objetivo. Describir las principales manifestaciones clínicas de la histiocitosis de células de Langerhans (HCL) en un hospital de tercer nivel en los últimos 14 años. Método. Estudio observacional, descriptivo y retrospectivo de los casos de HCL tratados en el Hospital Universitario Vall d’Hebron. Criterios de inclusión: edad de los participantes (de 0 días de vida hasta 18 años), período de estudio (2006-2021) y diagnóstico dela enfermedad, basado en el diagnóstico clínico o la confirmación histológica. Mediante la revisión de historias clínicas, se registraron variables demográficas (edad y sexo), clínicas (forma de presentación, manifestaciones iniciales, evolución y recaídas) y hallazgos relevantes en las pruebas complementarias. Resultados. Se revisaron 55 casos diagnosticados de HCL. La media de edad de presentación fue 4,5 años (RI 1-8), con predominio del sexo masculino (3:1). El motivo de consulta más frecuente ha sido la aparición de una tumoración (20%, sobre todo a nivel craneal), seguido por dolor óseo (14,5%), polidipsia y poliuria(9,1%), tortícolis (9,1%), cojera, exantema cutáneo y fiebre(7,3% cada una). Basándonos en la clasificación LCH-IV, la mayor parte se clasificaron como unisistémicas (71%) frente a las multisistémicas (29%). Conclusiones. La HCL es una enfermedad poco frecuente en pediatría pero con un amplio espectro clínico que comporta diagnósticos tardíos asociados a complicaciones. Resulta de gran importancia conocer a esta entidad y sus principales manifestaciones. (AU)

Background. Langerhans cell histiocytosis (LCH) is a disease characterized by the abnormal accumulation of cells of the monocytemacrophage system. Its clinical presentation is highly variable, which can lead to late diagnosis and worse outcomes.Objective. To describe the main clinical manifestations of LCH in atertiary hospital in the last 14 years. Method. Observational, descriptive, and retrospective study of children with LCH treated at the Hospital Universitari Vall d’Hebron.Inclusion criteria: age of the participants (0 days of life and up to18 years), study period (2006-2021) and diagnosis of the diseasebased on clinical diagnosis or histological confirmation. We recorded demographic variables (age and sex), clinical characteristics(form of presentation, initial manifestations, evolution, and relapses), and relevant findings in diagnostic tests. Results. 55 children diagnosed with LCH were reviewed. The meanage at presentation was 4.5 years (IR 1-8), with a predominanceof males (3:1). The most frequent reason for consultation was the appearance of a lump (20%, especially at the cranial level), followed by bone pain (14.5%), polydipsia and polyuria (9.1%), torticollis (9.1%), and limping, skin rash, and fever (7.3% each). Based on the LCH-IV classification, most were classified as singlesystem (71%) versus multi-system (29%). Conclusions. LCH is a rare disease in pediatrics but with a wideclinical spectrum that can lead to late diagnoses and subsequentcomplications. It is of great importance to know this entity and itsmain manifestations. (AU)

Clinical and pathological evaluation of cladribine treatment response in a case series of patients with xanthoma disseminatum.

BACKGROUND: Xanthoma disseminatum (XD) is a rare form of non-Langerhans histiocytosis with extensive cutaneous involvement. There is a paucity of evidence-based recommendations for treatment decision-making. Previous case reports have established purine analogues, especially cladribine, as a hopeful first-line treatment option, but characterization of the clinical and pathological responses is lacking. OBJECTIVES: To characterize the clinical and pathological responses to cladribine monotherapy based on serial examinations in XD patients. MATERIALS & METHODS: We retrospectively studied the clinical, pathological and laboratory data in a cohort of five XD patients who received intravenous cladribine monotherapy with serial examinations in our hospital. Compared with baseline characteristics, changes in clinical features and pathological patterns were identified and analysed. We also conducted a literature review of reported cases of cladribine treatment in XD patients. RESULTS: Four male and one female patient were involved in the study. All patients demonstrated satisfactory clinical responses to cladribine monotherapy after 5 to 10 cycles. We observed a pathological shift in pattern from classic xanthogranuloma to transitional fibrohistiocytic infiltration during the treatment, and pathological responses heralded persistent clinical improvement. Other than afebrile neutropenia, no prominent adverse events were identified. Sustainable lesion clearance was achieved in all five patients during the follow-up period, ranging from 19 to 66 months. CONCLUSION: Cladribine monotherapy is an effective and well-tolerated therapeutic option for XD patients. Pathological transformation is a signature of the clinical response and possibly unveils the underlying histiocyte biology of diseases in the xanthogranuloma family.

Multicentric Reticulohistiocytosis (Mrh): A Case Report On A Rare Destructive Arthritis.

Multicentric Reticulohistiocytosis is a rare disorder of unknown aetiology which affects skin and joints predominantly. There are no specific laboratory investigations for diagnosis. Diagnosis can be made clinically and on a histopathological basis. There is no consensus on treatment. We report a case from Pakistan with classical presentation who did well on methotrexate and low dose steroids. Prompt diagnosis and early treatment may save from significant disability.

Histiocytoid melanoma: Diagnostic pitfall and mimicker of non-Langerhans cell histiocytoses including reticulohistiocytoma.

Melanoma and benign histiocytic proliferations can sometimes show considerable clinical and histopathologic overlap. Recently, cases of melanomas resembling xanthogranuloma and Rosai-Dorfman disease have been reported, and herein we report a case of melanoma closely mimicking reticulohistiocytoma. An 84-year-old man presented with a 1 cm purple-red nodule on his arm concerning for squamous cell carcinoma. While the biopsy findings resembled reticulohistiocytoma, the clinical context and regression changes at the lesion perimeter raised stronger concern for melanoma, which was confirmed with immunohistochemistry. We review prior rare reports of melanomas resembling non-Langerhans cell histiocytic proliferations and summarize helpful clinical and histopathologic clues to avoid a diagnostic pitfall when confronted with this unusual quandary.

Reddish-brown, papulonodular skin lesions in the periungual region.

Multicentric reticulohistiocytosis is a rare, non-Langerhans cell histiocytosis that most commonly presents in women in their fourth or fifth decades of life. Cutaneous involvement, characterized by reddish-brown papules in a "string of pearls" or "coral bead" linear formation, and joint involvement are the two most common manifestations at presentation. Histopathology demonstrates dermal proliferation of epithelioid histiocytic-appearing cells with ground glass cytoplasm. We report a 51-year-old woman who presented with ruddy, periungual papules and bilateral joint pain in the hands, consistent with multicentric reticulohistiocytosis. We describe the clinical and histopathologic presentation, therapeutic options, and differential diagnosis of this rare condition.

Novel ANKRD26 and PDGFRB gene mutations in pediatric case of non-Langerhans cell histiocytosis: Case report and literature review.

Cutaneous non-Langerhans cell histiocytosis (NLCH) is a rare and biologically benign entity that can be broadly classified into two categories: xanthogranuloma and non-xanthogranuloma. The xanthogranuloma family is characterized by a proliferation of histiocytes with both macrophage and dendritic cell differentiation, negative BRAF mutation, and rare Touton-type giant cells. Molecular studies have reported that mutations involved in the MAPK signaling pathways are implicated in the pathophysiology of histiocytoses. While LCH is associated with the somatic mutation of BRAF v600e, however, mutations and gene fusions in NLCH cases are undefined. We hereby present a 19-month-old female with recalcitrant nodular rashes diagnosed as NLCH with associated novel genetic mutation involving ANKRD26 and PDGFRB genes, as well as PDGFRB::CD74 fusion mRNA. Immunohistochemical staining showed strong and diffuse CD68 and CD163 positivity, and negative CD1a, CD207, ALK D5F3, S100 protein, and BRAF V600E (VE1). Albeit unknown significance, this case of an ANKRD26 and PDGFRB gene mutation in cutaneous NLCH has not been reported prior in the literature. Our case highlights the advantage of pathology and genetic studies in cutaneous NLCH to increase the understanding of this heterogeneous enigmatic disorder and identify further options in management.

Multicentric reticulohistiocytosis with eosinophilic gastroenteritis: An unusual relationship.

Multicentric reticulohistiocytosis (MRH) is a rare disease with poorly defined therapeutic strategies. Here, we report the case of a patient with eosinophilic gastroenteritis who developed MRH after 5 years. The patient presented with disabling and rapidly progressive polyarthralgia, eosinophilic gastroenteritis, and resistance to first-line therapies. However, there was a marked improvement in the arthritis symptoms following treatment with tofacitinib. This presentation provides a useful perspective for the therapeutic management of complex scenarios involving MRH.