Juvenile xanthogranulomas: Examining single, multiple, and extracutaneous presentations

Fifth Edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues: Acute Lymphoblastic Leukemias, Mixed-Phenotype Acute Leukemias, Myeloid/Lymphoid Neoplasms With Eosinophilia, Dendritic/Histiocytic Neoplasms, and Genetic Tumor Syndromes

This manuscript represents a review of lymphoblastic leukemia/lymphoma (acute lymphoblastic leukemia/lymphoblastic lymphoma), acute leukemias of ambiguous lineage, mixed-phenotype acute leukemias, myeloid/lymphoid neoplasms with eosinophilia and defining gene rearrangements, histiocytic and dendritic neoplasms, and genetic tumor syndromes of the 5th edition of the World Health Organization Classification of Tumors of the Hematopoietic and Lymphoid Tissues. The diagnostic, clinicopathologic, cytogenetic, and molecular genetic features are discussed. The differences in comparison to the 4th revised edition of the World Health Organization classification of hematolymphoid neoplasms are highlighted.

Paediatric Orbital Juvenile Xanthogranuloma: A Case Series and Review of the Literature

PURPOSE

Juvenile xanthogranuloma (JXG) is a subtype of histiocytosis characterised histologically by foamy non-Langerhan cells with Touton giant cells. It typically manifests as a single self-limiting cutaneous nodule in the paediatric population. Orbital JXG is extremely rare, and its clinical course and management are not well understood or defined. Herein we present 3 cases of orbital JXG and provide a detailed literature review.

METHODS

Review of 3 cases with orbital JXG and literature review of all published cases.

RESULTS

Three presented cases demonstrate the heterogeneous clinical course of orbital JXG. Although centred around the use of steroids, there is neither robust evidence nor consensus on its management. The wider JXG literature is currently concentrated around the classification of JXG with respect to histiocytosis, especially the exclusion of extracutaneous JXG as separate diseases. This separation is based on clinical, histopathological, and molecular findings. It is unclear where orbital JXG best fits in this emerging classification of JXG.

CONCLUSION

Our review of the cases and literature on orbital JXG show that it may manifest with variable clinical course and its molecular pathogenic mechanism may be different to that of the cutaneous JXG.

Dermatologic manifestations of hematologic disorders

Distinguishing key morphologic features and understanding the pathophysiology of common cutaneous manifestations of hematologic disorders is essential to ensure prompt and appropriate treatment. In fact, classic cutaneous signs may provide the first clue to the diagnosis of an underlying hematologic disease. Disorders of coagulation, vascular abnormalities, or cutaneous infiltration and deposition are responsible for the underlying pathophysiology of cutaneous manifestations in the majority of cases. Hematologists often feel ill-equipped in identifying morphologic changes in the skin. Thus, the purpose of this review is to provide a comprehensive overview of classic cutaneous manifestations and diagnostic considerations of the associated hematologic conditions. Though there is a specific focus on non-malignant disorders, those straddling the spectrum of malignancy are also discussed. In many disease states, the skin may serve as an important marker of an emerging hematologic disorder, so close collaboration and multidisciplinary input remain essential to provide optimal and timely care for these patients.

NTRK expression is common in xanthogranuloma and is associated with the solitary variant

BACKGROUND

Previously identified mutually-exclusive driver genes in juvenile xanthogranuloma (JXG) and adult xanthogranuloma (AXG) include mutations in MAP kinase pathway genes such as MAP2K1, BRAF, ARAF, KRAS, NRAS, PIK3CD as well as fusions in BRAF and ALK, with a subset of cases with no identified driver yet. NTRK fusion has been identified in rare cases.

METHODS

We identified two consecutive index cases of localized JXG or AXG with NTRK1 fusion by next-generation sequencing (NGS) and confirmed by pan-NTRK immunostain. We expanded the study to a total of 50 cases of JXG and AXG using screening by pan-NTRK immunostain. We confirmed the specificity of our approach with negative results in 5 cases of histiocytic neoplasia lacking an NTRK fusion by NGS and 14 cases of non-neoplastic histiocytic disease.

RESULTS

We found 23 cases of JXG or AXG with overexpression of NTRK by immunostain, and these cases were restricted to localized disease (23 of 43 cases, 53.5%) rather than disseminated disease (zero of seven cases).

CONCLUSIONS

NTRK expression is common in JXG or AXG and associated with localized rather than disseminated disease. We speculate that the potential importance of this in JXG and AXG has not been previously appreciated due to the tendency to focus sequencing studies on disseminated disease. We confirm the presence of an NTRK1 fusion in two positive cases by NGS, however, additional genetic studies are necessary to further explore this.

The changing landscape of pediatric histiocytoses: Birth, life, and transdifferentiation of pediatric histiocytes

Histiocytic neoplasms in the children are very rare, and histiocytoses can occur in the perinatal period. The presumed origins and presentation of specific histiocytoses in the pediatric age group are described. Common and newly described histiocytoses are presented including Langerhans cell histiocytosis, Rosai-Dorfman disease, histiocytic sarcoma, ALK positive histiocytosis, and hemophagocytic lymphohistiocytosis. Molecular findings common to pediatric histiocytoses are also discussed.

Annular skin tumors and lymphoproliferative diseases

Determining the shape of a skin lesion may provide a diagnostic clue in dermatology practice, more commonly for inflammatory diseases but also for skin tumors. The annular formation may develop by diverse mechanisms in skin tumors. Annular lesions may occur from the onset of the tumor as sparing the central area or depression and/or ulceration in the center of the tumor or outward expansion of the primary lesion. Clustering of multiple papulonodular lesions sparing the central area or relatively independent processes acting on the central and peripheral components of the tumor may also result in an annular appearance. We have explored a wide variety of benign and malignant skin tumors and lymphoproliferative diseases forming an annular shape.

Bilateral anterior uveitis as a presenting feature of Juvenile Xanthogranuloma in a neonate

Purpose

To report a case of diffuse xanthogranuloma presenting as bilateral anterior uveitis in a neonate.

Observations

A neonate was brought by the parents with complaints of redness, watering, and photophobia in both eyes for 10 days. Examination under anesthesia revealed the presence of bilateral hyphema, fibrinous membrane, corneal haze, and raised intraocular pressure (IOP). Ultrasound Biomicroscopy revealed diffuse bilateral iris thickening. The child was managed medically with topical glaucoma medications, topical steroids, and cycloplegics. The child responded well with the resolution of hyphema, anterior chamber inflammation, and reduction of IOP.

Conclusion and importance

In neonates and infants presenting with bilateral uveitis, spontaneous hyphema, and secondary glaucoma, even in the absence of a well-defined iris lesion, diffuse juvenile xanthogranuloma should be considered as a differential diagnosis.

Annular skin tumors and lymphoproliferative diseases

Determining the shape of the skin lesion may provide a diagnostic clue in dermatology practice, more commonly for inflammatory diseases but also for skin tumors. The annular formation may develop by diverse mechanisms in skin tumors. Annular lesions may occur from the onset of the tumor as sparing the central area or depression and/or ulceration in the center of the tumor or outward expansion of the primary lesion. Clustering of multiple papulonodular lesions sparing the central area or relatively independent processes acting on the central and peripheral components of the tumor may also result in an annular appearance. We have explored a wide variety of benign and malignant skin tumors and lymphoproliferative diseases forming an annular shape.

Approach to Fine Needle Aspiration of Giant Cell-rich Tumors of Soft Tissue

Giant cells may be found in a wide variety of reactive and neoplastic soft tissue lesions. Because of their distinct histomorphology, they often stand out in procured samples such as fine needle aspirates. The giant cells themselves may be benign or neoplastic. However, the presence, type, and quantity of giant cells are usually not specific and in some cases can even be misleading when making a diagnosis. The aim of this review is to guide the practicing cytopathologist in narrowing their differential diagnosis when encountering one of these challenging giant cell-rich lesions of the soft tissue.

Juvenile Xanthogranuloma: A Comparative Immunohistochemical Study of Factor XIIIa, CD11c, and CD4

ABSTRACT

Juvenile xanthogranuloma is a group C and L non-Langerhans cell histiocytosis, and its cell of origin is still debatable. The expression of CD11c, a more recently described macrophage marker, and CD4 have not been studied comprehensively. This study aimed to expand immunophenotypic profile and hence our understanding of the origin of these lesions. The surgical pathology archive was searched for the cases with the pathologic diagnosis of "xanthogranuloma" from 1995 to 2019. Immunohistochemical (IHC) stains were performed for factor XIIIa, CD11c, and CD4. Morphologically, each lesion was classified into early classic, classic, or transitional subtypes. Seventy-seven cases were included with the median age of 7.8 years (male:female 1.3:1). Uniform positivity was noticed for CD4 (n = 77), CD68 (n = 37), CD163 (n = 5), and vimentin (n = 4) stains. Other stains included CD11c 75/77 (97.4%), factor XIIIa 71/76 (93.4%), S-100 protein 4/23 (17.4%), and CD1a 0/18 (0%). Despite insignificant association between morphologic subtype and main studied IHC stains, factor XIIIa reactivity was highest in transitional lesions and CD11c showed higher reactivity in early classic lesions. CD11c and CD4 are sensitive markers and showed promising results in the diagnosis of juvenile xanthogranuloma compared with factor XIIIa. Despite different reactivity of factor XIIIa and CD11c in various morphologic subtypes, such association was statistically insignificant.

Disseminated juvenile xanthogranulomas with ocular involvement: A case report and literature review

Cutaneous juvenile xanthogranuloma is an uncommon disorder usually arising during infancy. Systemic involvement of juvenile xanthogranuloma remains rare, and there are no published guidelines to date on screening extracutaneous manifestations in these patients. Ocular involvement is the most common extracutaneous manifestation of juvenile xanthogranuloma. We present the case of an infant with disseminated juvenile xanthogranulomas and associated ocular involvement and present a review of literature, focusing on identifying risk factors for ocular and systemic involvement in disseminated cases.

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.

Current Treatment of Juvenile Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare pediatric leukemia characterized by mutations in five canonical RAS pathway genes. The diagnosis is made by typical clinical and hematological findings associated with a compatible mutation. Although this is sufficient for clinical decision-making in most JMML cases, more in-depth analysis can include DNA methylation class and panel sequencing analysis for secondary mutations. NRAS-initiated JMML is heterogeneous and adequate management ranges from watchful waiting to allogeneic hematopoietic stem cell transplantation (HSCT). Upfront azacitidine in KRAS patients can achieve long-term remissions without HSCT; if HSCT is required, a less toxic preparative regimen is recommended. Germline CBL patients often experience spontaneous resolution of the leukemia or exhibit stable mixed chimerism after HSCT. JMML driven by PTPN11 or NF1 is often rapidly progressive, requires swift HSCT and may benefit from pretransplant therapy with azacitidine. Because graft-versus-leukemia alloimmunity is central to cure high risk patients, the immunosuppressive regimen should be discontinued early after HSCT.

Juvenile xanthogranuloma in Noonan syndrome

Noonan syndrome (NS) is one of the common RASopathies. While the clinical phenotype in NS is variable, it is typically characterized by distinctive craniofacial features, cardiac defects, reduced growth, bleeding disorders, learning issues, and an increased risk of cancer. Several different genes cause NS, all of which are involved in the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway. Juvenile xanthogranuloma (JXG) is an uncommon, proliferative, self-limited cutaneous disorder that affects young individuals and may be overlooked or misdiagnosed due to its transient nature. A RASopathy that is known to be associated with JXG is neurofibromatosis type 1 (NF1). JXG in NF1 has also been reported in association with a juvenile myelomonocytic leukemia (JMML). As RASopathies, both NS and NF1 have an increased incidence of JMML. We report a 10-month-old female with NS who has a PTPN11 pathogenic variant resulting in a heterozygous SHP2 p.Y62D missense mutation. She was found to have numerous, small, yellow-pink smooth papules that were histopathologically confirmed to be JXG. In understanding the common underlying pathogenetic dysregulation of the Ras/MAPK pathway in both NS and NF1, this report suggests a possible molecular association for why NS individuals may be predisposed to JXG.

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.