Overview of histiocytic and dendritic disorders by the 5th version of WHO Classifi cation of Hematolymphoid Tumours from 2022.

BACKGROUND: Histiocytoses are rare disorders characterized by the accumulation of macrophages, dendritic cells, or monocyte-derived cells in various tissues and organs of children and adults, with a wide range of clinical manifestations, presentations, and histology. The histiocytoses are classified according to the WHO Classification, the last version of which was published in 2022, or according to the Histiocyte Society Classification, with the last version published in 2016. PURPOSE: This text provides an overview of histiocytoses as described in the WHO Classification 2022.

A novel start-loss mutation of the SLC29A3 gene in a consanguineous family with H syndrome: clinical characteristics, in silico analysis and literature review.

BACKGROUND: The SLC29A3 gene, which encodes a nucleoside transporter protein, is primarily located in intracellular membranes. The mutations in this gene can give rise to various clinical manifestations, including H syndrome, dysosteosclerosis, Faisalabad histiocytosis, and pigmented hypertrichosis with insulin-dependent diabetes. The aim of this study is to present two Iranian patients with H syndrome and to describe a novel start-loss mutation in SLC29A3 gene. METHODS: In this study, we employed whole-exome sequencing (WES) as a method to identify genetic variations that contribute to the development of H syndrome in a 16-year-old girl and her 8-year-old brother. These siblings were part of an Iranian family with consanguineous parents. To confirmed the pathogenicity of the identified variant, we utilized in-silico tools and cross-referenced various databases to confirm its novelty. Additionally, we conducted a co-segregation study and verified the presence of the variant in the parents of the affected patients through Sanger sequencing. RESULTS: In our study, we identified a novel start-loss mutation (c.2T > A, p.Met1Lys) in the SLC29A3 gene, which was found in both of two patients. Co-segregation analysis using Sanger sequencing confirmed that this variant was inherited from the parents. To evaluate the potential pathogenicity and novelty of this mutation, we consulted various databases. Additionally, we employed bioinformatics tools to predict the three-dimensional structure of the mutant SLC29A3 protein. These analyses were conducted with the aim of providing valuable insights into the functional implications of the identified mutation on the structure and function of the SLC29A3 protein. CONCLUSION: Our study contributes to the expanding body of evidence supporting the association between mutations in the SLC29A3 gene and H syndrome. The molecular analysis of diseases related to SLC29A3 is crucial in understanding the range of variability and raising awareness of H syndrome, with the ultimate goal of facilitating early diagnosis and appropriate treatment. The discovery of this novel biallelic variant in the probands further underscores the significance of utilizing genetic testing approaches, such as WES, as dependable diagnostic tools for individuals with this particular condition.

Sequential occurrence of primary cutaneous indeterminate cell histiocytosis after oesophageal cancer and subsequent bullous pemphigoid: a case report.

Aims/Background Indeterminate cell histiocytosis is a rare proliferative histiocytic disease with an unknown aetiology, which shares immunophenotypic features of both Langerhans cells and macrophages. There is a relationship between indeterminate cell histiocytosis and cancer, while there are no reports about indeterminate cell histiocytosis and bullous pemphigoid. In this study, we reported the rare case of a patient with primary cutaneous indeterminate cell histiocytosis who had been diagnosed with oesophagal cancer and later developed bullous pemphigoid. The objective of this clinical case report is to analyse the association between solid tumours and indeterminate cell histiocytosis and focus on the coexistence of indeterminate cell histiocytosis and bullous pemphigoid in a patient with cancer. Case Presentation This study presented the case of a 75-year-old man who exhibited annular erythema lesions of variable size and papules scattered over his chest, abdomen, and limbs, along with four bullae on his thigh, persisting for 1.5 months. The patient also had a 9-month history of oesophageal cancer treated with radical radiotherapy. Histopathology and immunohistochemistry confirmed cutaneous indeterminate cell histiocytosis. Bullae and blisters developed on the lower limbs 38 days after treatment. A diagnosis of bullous pemphigoid was established based on clinical and histopathological features and results of direct immunofluorescence and enzyme-linked immunosorbent assay. Results Histopathological examination of the abdominal lesion revealed an accumulation of mononuclear cells in the dermis, with infiltration of eosinophils and lymphocytes in the superficial dermal layer. The histology of the blister on the thigh indicated the formation of an old subepidermal blister, with slurry and eosinophils present within the blister, and infiltration of eosinophils, lymphocytes, as well as histiocytoid cells in the superficial dermal layer. Immunohistochemical staining was positive for CD1a, S100, and CD68, and negative for CD207. Histopathological examination of blisters and bullae on the lower limbs revealed a subepidermal blister with infiltration of a large number of eosinophils within the blister and the dermis beneath it. Direct immunofluorescence showed that immunoglobulin Gs (IgGs) were linearly deposited in the basal membrane zone. Conclusion The coexistence of oesophageal carcinoma, indeterminate cell histiocytosis, and bullous pemphigoid in a single patient represents a rare case that warrants consideration of possible underlying mechanisms.

Treatment of Cerebral Histiocytosis With Low Dose of Cobimetinib: A Report of 2 Cases.

OBJECTIVES: Histiocytic disorders are pathologic expansions of myeloid cells in multiple organs, including the CNS. They share activation of the MAP kinase pathway due to either BRAFV600E variant or other variants in the RAS-RAF-MEK-ERK pathway. The rarity and heterogeneity of the disease only enable therapy through pathophysiologic considerations. METHODS: We present 2 histiocytosis cases without BRAF sequence variants that affect the CNS, one with Erdheim-Chester disease and the other with an unspecified histiocytosis, and their diagnostic and therapeutic challenges. RESULTS: In both cases, comprehensive analysis of the RAS-RAF-MEK-ERK signaling pathway secured the diagnosis. Treatment with the MEK inhibitor cobimetinib brought the disease to a complete halt. However, side effects such as thrombosis and serous macular edema made it necessary to reduce cobimetinib dosage. Low-dose cobimetinib maintenance medication was successful in preventing recurrence of histiocytic disease. DISCUSSION: CNS involvement of histiocytic disorders can lead to detrimental neurologic symptoms. MEK inhibitors are effective treatment options for some of these patients. Since side effects are common, according to our cases we propose a low-dose treatment of 20 mg per day to balance treatment effects with side effects. CLASSIFICATION OF EVIDENCE: This case report provides Class IV evidence. This is a single observational study without controls.

Cutaneous crystal storing histiocytosis: A case series with review of literature.

Crystal-storing histiocytosis (CSH) is a rare condition in which crystals accumulate in the cytoplasm of histiocytes and is usually associated with a lymphoplasmacytic neoplasm. Cutaneous CSH is extraordinarily rare and limited to case reports in the literature. We report two cases of this disease with cutaneous involvement. Case 1 was a 65-year-old male with a 4-month history of a pruritic eruption that started as a solitary pink to skin-colored indurated plaque on the anterior neck before progressing to involve the whole neck, chest wall, and face. Case 2 was a 54-year-old woman with a history of unspecified "lymphoma" who presented with a soft nodule on the forearm. Biopsies from both cases had similar findings and showed a proliferation of epithelioid cells with pink cytoplasm and intracellular crystalline structures infiltrating the dermis and subcutaneous fat. In the first case, the cells were positive for CD43, CD45, CD68, and IgG kappa, and in the second case, the crystals were positive for IgG lambda. Based on these findings, the patients were diagnosed with cutaneous CSH. We highlight this rare diagnosis and the importance of investigating an underlying lymphoplasmacytic neoplasm.

Anaplastic lymphoma kinase-positive histiocytosis with multisystem involvement: A case report.

Anaplastic lymphoma kinase (ALK)-positive histiocytosis is a rare disease that usually occurs in infants and young children and is characterized by ALK-positive histiocytes infiltrating organs. We present a case of multisystem involvement of ALK-positive histiocytosis in a female infant with skin nodules as the initial presentation. Despite multiorgan involvement, most tumors had spontaneously regressed, and all bones were partially healed after 40 months of regular follow-up without treatment. However, gait abnormalities persisted, indicating that early treatment may have greater impact in maintaining a child's quality of life when the disease involves the brain or the critical period of bone development.

Lesiones óseas en enfermedad de Erdheim-Chester / Bone lesions in Erdheim-Chester disease

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Intravascular histiocytosis: case report of a rare disease probably associated with silicone breast implant

Abstract Intravascular histiocytosis is a rare condition characterized by the aggregate of histiocytes within dilated dermal vessels. The diagnosis is mainly histophatological and immunohistochemical. We describe a case of a 55 year-old female patient presenting erythematous/purple patches on the breasts, back and limbs. She previously presented ductal carcinoma in the right breast in 2006 which was treated with mastectomy and proceeded to silicone breast implant in 2009. Clinical hypothesis was telangiectatic metastatic carcinoma. Histopathology showed vascular ectasia, thrombosis and recanalization of upper dermis small vessels. On immunohistochemistry, intravascular cells were CD 68+ and negative for estrogen and progesterone receptors, CK7, EMA and AE1/AE3 and endothelial cells were CD64+, leading to the diagnosis of intravascular histiocytosis.

Depósito de lantano en la mucosa gástrica de paciente con enfermedad renal crónica / Deposits of lanthanum in the gastric mucosa of a patient with chronic kidney disease

El carbonato de lantano es un quelante de fósforo no cálcico utilizado en el tratamiento de la hiperfosfatemia asociada a la enfermedad renal crónica. Los depósitos de lantano en la pared gastrointestinal han sido descritos desde 2015. Su significado clínico es incierto. Describimos un caso de paciente varón de 62 años con enfermedad renal crónica en tratamiento con carbonato de lantano durante 3 años, quien presentó depósitos en la mucosa gástrica biopsiada por dispepsia. Los depósitos se observaban como material acelular, con formas irregulares, rodeados de macrófagos y con reacción gigantocelular. Se confirmó la presencia de lantano en los depósitos mediante estudio de espectroscopia de rayos X. En su diagnóstico diferencial con otros depósitos, la clave para hacer su correcta identificación es la realización de una detallada historia clínica que incluya medicamentos administrados y el conocimiento de su aspecto microscópico

Lanthanum carbonate is a non-calcium phosphorus chelator used in the treatment of hyperphosphatemia associated with chronic renal disease. Deposits of lanthanum in the gastrointestinal wall have been recently described but its clinical significance is uncertain. We present a case of a 62-year-old male with chronic renal disease treated with lanthanum carbonate for 3 years, with deposits in his gastric mucosa, found on biopsy for dyspepsia. The deposits were acellular and of irregular shape, surrounded by macrophages and foreign body giant cells. The presence of lanthanum in the deposits was confirmed by X-ray spectroscopy. Diagnosis is reached with knowledge of its microscopic appearance and a thorough clinical history

Histiocitosis eruptiva generalizada-xantogranuloma juvenil: espectro clínico en un paciente pediátrico / Generalized eruptive histiocytosis-Juvenile xanthogranuloma: clinical spectrum in a pediatric patient

La histiocitosis eruptiva generalizada, conjuntamente con el xantogranuloma juvenil, constituyen desórdenes histiocíticos de origen dendrítico (también denominados histiocitosis no Langerhans), que comparten características clínico-patológicas e inmunohistoquímicas. Presentamos a una paciente de 3 años de edad con lesiones en la piel clínicamente compatibles con histiocitosis eruptiva generalizada y confirmadas mediante histología e inmunohistoquímica. Luego presentó compromiso en el sistema nervioso central, por lo que fue intervenida quirúrgicamente. En la histopatología de esta lesión, se encontraron células de Touton, compatibles con el diagnóstico de xantogranuloma juvenil. Este caso clínico demuestra la necesidad de considerar estas enfermedades como espectro de una misma entidad.

Both, generalized eruptive histiocytosis and juvenile xanthogranuloma are dendritic histiocytic disorders (also known as non-Langerhans cells histiocytosis) that share clinicopathological and immunohistiochemical characteristics. We present a 3-year-old female patient with skin lesions that were clinically compatible with generalized eruptive histiocytosis, confirmed by histopathological and immunohistochemical studies. During her development the disorder compromised the central nervous system, and surgical intervention of one symptomatic lesion was needed. The histopathological exam of the central nervous system lesion showed Touton cells, compatible with a diagnosis of juvenile xanthogranuloma. This case demonstrates the need to consider these diseases as a spectrum of the same entity.

Enfermedad de rosai-dorfman / Rosai-dorfman disease

La enfermedad de Rosai-Dorfman, o sinuhistiocitosis con linfadenopatía masiva, es una rara patología que se presenta con linfadenopatía dolorosa generalizada, más frecuentemente en cabeza y cuello. Su curso clínico y tratamiento es variable. Se describe el caso de un paciente masculino con compromiso nasal de la enfermedad...

Rosai-Dorfman disease, or sinus histiocytosis with massive lymphadenopathy, is a rare disorder presented as painless bilateral lymph node enlargement mainly in the head and neck region. Clinical course and treatment regimen are variable. We described one male patient with nasal involment...

Histiocitose de células de Langerhans em otorrinolaringologia / Langerhans cell histiocytosis in otorhinolaryngology

Introdução: A histiocitose de células de Langerhans é um distúrbio proliferativo de células inflamatórias de etiologia desconhecida. É doença rara da faixa pediátrica. Objetivo: Realizar revisão de literatura sobre a histiocitose de células de Langerhans, focando as manifestações otorrinolaringológicas. Materiais e métodos: A metodologia utilizada foi consulta à base de dados on line MEDLINE, de 1966 a 2008, pesquisando a partir dos termos histiocitose de células de Langerhans, osso temporal e otorrinolaringologia. Revisão da Literatura: As manifestações em cabeça e pescoço são as mais frequentes e seu diagnóstico torna-se difícil uma vez que mimetiza outras doenças mais comuns vistas pelo otorrinolaringologista, como otite externa, mastoidite aguda e gengivite. A doença no osso temporal expressa-se como otorreia de repetição e granulomas de conduto auditivo externo ou retroauricular. A avaliação radiológica evidencia lesões líticas principalmente em calota craniana, mandíbula, osso temporal e costelas. O diagnóstico definitivo é feito por biópsia através dos achados histopatológicos e detecção pela imunohistoquímica do antígeno CD1a. A principal forma de tratamento é a quimioterapia e, em menor escala, radioterapia ou cirurgia. Conclusões: Manifestações otorrinolaringológicas devem ser suspeitadas por sintomas otológicos recorrentes e pela presença de tecido de granulação retroauricular ou de conduto auditivo externo. A biópsia com achados histológicos característicos e imunohistoquímica positiva para CD1a são diagnósticos. A quimioterapia pode ser o tratamento inicial na maioria dos casos ou adjuvante nas formas refratárias ou recorrentes.

Introduction: The Langerhans cell histiocytosis is an inflammatory cells proliferative disorder of unknown etiology. It is uncommon disease in children. Objective: To proceed with a literature review on Langerhans cell histiocytosis, with focus on the otorhinolaryngological complications. Materials and methods: The methodology used was advised based on online data from MEDLINE, between 1966 and 2008, with research of terms related to Langerhans cell histiocytosis, temporal bones and otorhinolaryngology. Literature Review: The manifestations in the head and neck are the most common ones and their diagnosis becomes difficult once it mimetizing other more common diseases the otorhinolaryngologist sees as external ear eczema, acute mastoiditis and gingivitis. The temporal bone disease manifests as recurrent otorrhea and external auditory meatus and retroauricular granulomas. The radiological evaluation confirms lytic lesions especially in the cranial cap, jaw, temporal bones and spines. The definitive diagnosis is made by biopsy through the histopathological discoveries and immunohistochemistry detection of the CD1a antigen. The main form of treatment is by chemotherapy and, in a lower scale, radiotherapy or surgery. Conclusions: he otorhinolaryngological manifestations must be suspected for recurrent otological symptoms and the presence of retroauricular granulation tissue or and the external auditory meatus. The biopsy with characteristic histological discoveries and immunohistochemistry positive for CD1a were diagnostic. The chemotherapy may be the initial treatment in most cases or secondary in refractory or recurrent forms.