Long-term outcomes of children with extracutaneous juvenile xanthogranulomas in Japan

Recurrent CLTC::SYK fusions and CSF1R mutations in juvenile xanthogranuloma of soft tissue

ABSTRACT

Juvenile xanthogranuloma (JXG) is a histiocytic neoplasm that usually presents in the skin. Rarely, extracutaneous localizations occur; the genetic drivers of this clinical variant of JXG remain incompletely characterized. We present detailed clinicopathologic and molecular data of 16 children with extracutaneous JXG and 5 adults with xanthogranulomas confined to the central nervous system (CNS) or soft tissue. Tissue samples were obtained through the Dutch Nationwide Pathology Databank and analyzed with an innovative sequencing technique capable of detecting both small genomic variants and gene rearrangements. Targetable kinase alterations were detected in 16 of 16 children and 1 of 5 adults. Alterations included CLTC::SYK fusions in 6 children and CSF1R mutations in 7 others; all below 2 years of age with soft tissue tumors. One child had a CSF1R mutation and MRC1::PDGFRB fusion. Most were treated surgically, although spontaneous regression occurred in 1 of 6 with CLTC::SYK and 2 of 7 with CSF1R mutations, underscoring that treatment is not always necessary. Tumors with CLTC::SYK fusions generally lacked Touton giant cells but exhibited many other histologic features of JXG and concordant methylation profiles. Using multispectral immunofluorescence, phosphorylated-spleen tyrosine kinase expression was localized to CD163+ histiocytes; tumors with CLTC::SYK fusions also demonstrated mTOR activation, cyclin D1 expression, and variable phosphorylated-extracellular signal-regulated kinase expression. BRAFV600E was detected in 1 child and 1 adult with CNS-xanthogranulomas; both responded to BRAF inhibition. Finally, a TPM3::NTRK1 fusion or MAP2K1 deletion was detected in 2 children with systemic JXG who experienced spontaneous disease regression. This study advances the molecular understanding of histiocytic neoplasms and may guide diagnostics and clinical management.

Clinical features and outcomes of 17 children with systemic juvenile xanthogranuloma (sJXG) including five complicated with hemophagocytic lymphohistiocytosis (HLH)

Juvenile xanthogranuloma (JXG) is primarily limited to the skin, and systemic JXG (sJXG) is rarely reported. Reports of sJXG patients with hemophagocytic lymphohistiocytosis (HLH) are particularly rare. Herein, we conducted a retrospective study of children diagnosed with sJXG in the Hematology Centre of Beijing Children's Hospital from Jan. 2016 to Dec. 2021. The clinical features, laboratory parameters, treatments and outcomes of 17 sJXG patients were investigated, including five complicated with HLH. All sJXG-HLH patients had intermittent fever, rash, hepatosplenomegaly, cytopenia and high levels of soluble CD25, but interferon-γ was almost normal. Patients with sJXG-HLH had a younger diagnosis age (P = 0.035) and were more likely to have skin, liver, and spleen involvement than those without HLH (P = 0.029, P = 0.003, P = 0.003, respectively). Corticosteroids and/or ruxolitinib could be used to control the hyperinflammatory status when HLH was diagnosed. The treatment of sJXG varied, including Langerhans cell histiocytosis (LCH)-based chemotherapy and targeted therapy. The overall response rate of sJXG for first-line and second-line chemotherapy was 50.0% (5/10) and 50% (4/8), respectively. Patients with BRAF V600E mutation showed a response to dabrafenib. There was no significant difference in the overall survival and progression-free survival between sJXG patients without and with HLH (P = 0.12 and P = 0.46, respectively). Therefore, LCH-based chemotherapy could serve as an effective treatment for sJXG patients, and dabrafenib, to some extent, showed efficacy in controlling sJXG in patients with BRAF V600E mutation. The prognosis of sJXG-HLH patients seemed to be comparable to patients without HLH.

Juvenile xanthogranuloma manifesting with LCH-associated neurodegenerative disease-like radiological findings

Here, we describe two patients with juvenile xanthogranuloma (JXG) manifesting with Langerhans cell histiocytosis (LCH)-associated neurodegenerative disease (ND)-like radiological findings. One patient showed typical radiological abnormalities at onset, which worsened with progressing central nervous system symptoms 7 years after LCH-oriented chemotherapy. Another showed spontaneous regression of clinical symptoms, with a transient radiological change 1 year after salvage chemotherapy for recurrence of JXG. These data regarding JXG-associated ND will facilitate future investigation of the disease, as well as development of therapeutic interventions.

Histiocytic neoplasms: a brief review and differential diagnosis

Histiocytic neoplasms (HNs) include juvenile xanthogranuloma, Erdheim-Chester disease, Rosai-Dorfman disease, ALK-positive histiocytosis, and histiocytic sarcoma in the 5th edition of the World Health Organization Classification of Haematolymphoid Tumours. These entities are clinicopathologically distinctive, and typical histological findings have been established. However, the common feature of a proliferation of histiocytic cells often leads to morphological overlap among HNs, and also necessitates a differential diagnosis from several non-HNs or non-neoplastic conditions. In this review, we provide a brief summary of the clinical findings, molecular features, histopathologies, and immunophenotypes of HNs, as well as to discuss their differential diagnosis.

Systemic juvenile xanthogranuloma: A systematic review

OBJECTIVE

To perform a systematic review to investigate the available literature regarding systemic juvenile xanthogranuloma (SJXG) and report the population characteristics, clinical manifestation, therapy, and outcome.

REVIEW METHODS

A search of PubMed, Embase, and Cochrane Library for all articles published between 1981 and 2022 was performed with variations and combinations of the following search terms: extracutaneous, visceral, systemic, and juvenile xanthogranuloma (JXG). Data extracted included demographics, organ involvement, treatment, outcome, and permanent sequelae.

RESULTS

A total of 103 articles encompassing 159 patients met the inclusion criteria. The median onset age was 9 months, with a male predominance (61%). The distribution of major involved organs varied by age, and younger onset age was associated with more organ involvement. The most commonly involved site was the central nervous system (CNS) (40.9%), followed by the liver (31.4%), the lung (18.9%), and the eye (18.2%). At the termination of follow-up, 93 patients (58.5%) were alive with no disease, 56 (35.2%) were alive with disease, and 10 (6.3%) were dead of disease. There was a significant difference in outcome between patients with and without spleen involvement (p = .0003), and patients with spleen involvement suffered a higher risk of death. Permanent sequelae mainly comprised CNS symptoms and ocular manifestations.

CONCLUSIONS

SJXG can involve varying numbers and combinations of extracutaneous sites. There is no standard therapy for SJXG and clinicians should choose individualized therapy modalities.

Xanthogranuloma of the Sellar Region: A Comprehensive Review of Neuroimaging in a Rare Inflammatory Entity

Xanthogranuloma of the sellar region is a rare chronic inflammatory lesion resulting from secondary hemorrhage, inflammation, infarction, and necrosis of an existing Rathke’s cleft cyst, craniopharyngioma, or pituitary adenoma. Sellar xanthogranulomas are challenging to differentiate from other cystic lesions preoperatively due to the lack of characteristic imaging features. We performed a literature overview of the clinical and paraclinical features, treatment options, and long-term outcomes of patients with sellar xanthogranuloma, focusing on the preoperative radiological diagnosis. The hyperintense signal in both T1- and T2-weighted sequences, cystic or partially cystic morphology, ovoid shape, sellar epicenter, intra- and suprasellar location, intratumoral calcifications, linear rim contrast enhancement, and the absence of cavernous sinus invasion suggest xanthogranuloma in the preoperative differential diagnosis. An endoscopic endonasal gross total resection without radiotherapy is the preferred first-line treatment. Given the low rate of recurrence rate and low chance of endocrinological recovery, a mass reduction with decompression of the optic apparatus may represent an appropriate surgical goal. Identifying the xanthogranulomas’ mutational profile could complement histopathological diagnosis and give insight into their histo-pathogenesis. A better preoperative neuroimagistic diagnosis of sellar xanthogranulomas and differentiation from lesions with a poorer prognosis, such as craniopharyngioma, would result in an optimal personalized surgical approach.

ALK-positive histiocytosis: a new clinicopathologic spectrum highlighting neurologic involvement and responses to ALK inhibition

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Ocular Involvement in the Histiocytoses: A Literature Review with an Illustrative Case Series

Purpose: To describe and illustrate recent reclassification and clinical descriptions of the histiocytoses, diagnosis and management, and effects on the eye and adnexaePatients and methods: Literature review with an illustrative case series of seven patients with histiocytosis and ophthalmic involvement from a single tertiary centre.Results: Skin lesions with signs including eyelid mass, orbital bone destruction, bizarre keratic precipitates, limbal or iris mass, haemorrhagic anterior uveitis, subretinal lesions of uncertain etiology, ischaemic retinopathy, optic neuropathy, and apparent steroid-resistant inflammations should be comprehensively investigated.Conclusions: Ophthalmic involvement in histiocytosis is rare. Clinical manifestations vary from limited single-organ disease to lethal systemic infiltration or malignancy. Radiology may identify lesions for biopsy. Histology with appropriate markers is essential. Oncology advice may be required.

Histiocytic disorders

The historic term 'histiocytosis' meaning 'tissue cell' is used as a unifying concept for diseases characterized by pathogenic myeloid cells that share histological features with macrophages or dendritic cells. These cells may arise from the embryonic yolk sac, fetal liver or postnatal bone marrow. Prior classification schemes align disease designation with terminal phenotype: for example, Langerhans cell histiocytosis (LCH) shares CD207+ antigen with physiological epidermal Langerhans cells. LCH, Erdheim-Chester disease (ECD), juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are all characterized by pathological ERK activation driven by activating somatic mutations in MAPK pathway genes. The title of this Primer (Histiocytic disorders) was chosen to differentiate the above diseases from Langerhans cell sarcoma and malignant histiocytosis, which are hyperproliferative lesions typical of cancer. By comparison LCH, ECD, RDD and JXG share some features of malignant cells including activating MAPK pathway mutations, but are not hyperproliferative. 'Inflammatory myeloproliferative neoplasm' may be a more precise nomenclature. By contrast, haemophagocytic lymphohistiocytosis is associated with macrophage activation and extreme inflammation, and represents a syndrome of immune dysregulation. These diseases affect children and adults in varying proportions depending on which of the entities is involved.

Clinical Analysis of Pediatric Systemic Juvenile Xanthogranulomas: A Retrospective Single-Center Study

Objective: To investigate the clinical characteristics, treatment, and prognosis of children with systemic juvenile xanthogranuloma (JXG). Methods: Clinical data of children with JXG who were hospitalized in Beijing Children's Hospital, Capital Medical University, from January 2012 to December 2019 were retrospectively analyzed, including clinical manifestations, laboratory determinations, treatment, and prognosis of the children. Patients were treated with vindesine + prednisone as the first-line treatment and cytarabine + vindesine + dexamethasone ± cladribine as the second-line treatment. Results: Ten patients, including 8 males and 2 females, with a median of onset age of 1.95 (0.80-7.30) years, exhibited multi-system dysfunction. The median age of diagnosis was 2.45 (1.30-12.10) years. The most common location of extracutaneous lesions was the central nervous system (6 cases), followed by the lung (5 cases) and bone (4 cases). Nine patients underwent first-line chemotherapy, and 6 patients underwent second-line chemotherapy, including 5 patients with poorly controlled disease after first-line treatment. The median observation time was 29 (3-115) months. Nine patients survived, whereas one patient died of respiratory failure caused by pulmonary infection. At the end of follow-up, 7 patients were in active disease (AD)/regression state (AD-better), and 2 patients were in an AD/stable state (AD-stable). Three patients had permanent sequelae, mainly central diabetes insipidus. The rates of response to the first-line treatment and the second-line treatment were 40.0 and 66.7% respectively. Conclusion: The chemotherapy protocol for Langerhans cell histiocytosis (LCH) may be effective for patients with systemic JXG. Central nervous system involvement may not impact overall survival, but serious permanent sequelae may occur.

Isolated endobronchial juvenile xanthogranuloma: a case report

Juvenile xanthogranuloma (JXG) is a rare non-Langerhans cell tumour usually diagnosed during infancy. The lesion is typically located in the skin; however, extracutaneous lesions have been described. The symptoms vary depending on the location and size of the lesion.

Presented here is a case of 13-year-old girl with this type of tumour located within the bronchus. She reported chest discomfort, difficulty breathing, and cough. A month prior to admission she had suffered from a respiratory tract infection. Prolonged surgical treatment was required due to the tumour’s atypical location and recurrence of the tumour following initial resection.

Isolated pulmonary JXG is an extremely rare finding, which requires accurate diagnosis and careful planning of therapeutic treatment. Severe pulmonary symptoms, inconclusive histopathological examination, malignancy risk, and large tumour size are indications for radical surgical resection of the tumour. Non-surgical treatment with chemotherapy is useful in cases of inoperable tumours.