Langerhans cell histiocytosis (LCH) is a rare neoplastic disorder caused by somatic genetic alterations in hematopoietic precursor cells differentiating into CD1a+/CD207+ histiocytes. LCH clinical... Show moreLangerhans cell histiocytosis (LCH) is a rare neoplastic disorder caused by somatic genetic alterations in hematopoietic precursor cells differentiating into CD1a+/CD207+ histiocytes. LCH clinical manifestation is highly heterogeneous. BRAF and MAP2K1 mutations account for ∼80% of genetic driver alterations in neoplastic LCH cells. However, their clinical associations remain incompletely understood. Here, we present an international clinicogenomic study of childhood LCH, investigating 377 patients genotyped for at least BRAFV600E. MAPK pathway gene alterations were detected in 300 (79.6%) patients, including 191 (50.7%) with BRAFV600E, 54 with MAP2K1 mutations, 39 with BRAF exon 12 mutations, 13 with rare BRAF alterations, and 3 with ARAF or KRAS mutations. Our results confirm that BRAFV600E associates with lower age at diagnosis and higher prevalence of multisystem LCH, high-risk disease, and skin involvement. Furthermore, BRAFV600E appeared to correlate with a higher prevalence of central nervous system (CNS)–risk bone lesions. In contrast, MAP2K1 mutations associated with a higher prevalence of single-system (SS)-bone LCH, and BRAF exon 12 deletions seemed to correlate with more lung involvement. Although BRAFV600E correlated with reduced event-free survival in the overall cohort, neither BRAF nor MAP2K1 mutations associated with event-free survival when patients were stratified by disease extent. Thus, the correlation of BRAFV600E with inferior clinical outcome is (primarily) driven by its association with disease extents known for high rates of progression or relapse, including multisystem LCH. These findings advance our understanding of factors underlying the remarkable clinical heterogeneity of LCH but also question the independent prognostic value of lesional BRAFV600E status. Show less
Background: Adult orbital xanthogranulomatous disease (AOXGD) is a group of rare disorders. Four subtypes are identified: adult-onset xanthogranuloma (AOX), adult-onset asthma and periocular... Show moreBackground: Adult orbital xanthogranulomatous disease (AOXGD) is a group of rare disorders. Four subtypes are identified: adult-onset xanthogranuloma (AOX), adult-onset asthma and periocular xanthogranuloma (AAPOX), necrobiotic xanthogranuloma (NBX), and Erdheim-Chester disease (ECD). Therapy options vary and little is known about the long-term effect of the treatment. In this study, we will describe the clinical behaviour, effect of treatment, and long-term outcome in a consecutive series of patients with AOXGD. Methods: This is a descriptive, retrospective study with a long follow-up term of 21 patients with histologically proven AOXGD, treated between 1989 and 2021 in the Rotterdam Eye Hospital and Erasmus MC University Medical Center. Results: Twenty-one patients with histologically proven AOXGD were included. The follow-up ranged from 2-260 months (median of 67 months). Six of the nine patients with AOX were treated with surgery alone, with recurrence in two. Three received systemic therapy, with recurrence in one. All four patients with AAPOX received systemic treatment, the disease recurred in two. Two patients with NBX were treated with surgery alone, with recurrence in one. Four required additional therapy with recurrence in two. Both patients with ECD required systemic therapy. Conclusions: Recognition of AOXGD is important, in particular, because of the potential severe systemic locations in the different subtypes. Surgical excision might be a sufficient therapy for patients with AOX. Patients with AAPOX, NBX, and ECD warrant systemic therapy. Currently, there is no conclusive evidence for a superior treatment strategy, but further studies are necessary to investigate treatment options. Show less
Ghuijs, W.; Kemps, P.G.; Capala, M.E.; Verdijk, R.M.; Halteren, A.G.S. van; Wal, R.J.P. van der; Laar, J.A.M. van 2022
Background Langerhans cell histiocytosis (LCH) is a rare haematological neoplasm characterized by the accumulation of CD1a(+), CD207/Langerin(+) histiocytes within inflammatory lesions. LCH can... Show moreBackground Langerhans cell histiocytosis (LCH) is a rare haematological neoplasm characterized by the accumulation of CD1a(+), CD207/Langerin(+) histiocytes within inflammatory lesions. LCH can involve any organ, but osteolytic bone lesions are most often encountered. Unifocal bone lesions may regress spontaneously after a thick needle biopsy has been taken. Case presentation In this case report, we describe the initial presentation of a single BRAF(V600E) mutated osteolytic LCH lesion in the left proximal humerus of a 46-year-old previously healthy woman. Despite multiple surgical interventions, she unexpectedly experienced progressive disease manifestation with significant soft tissue extension to the surrounding musculature, subcutis and epidermis. Because the disease manifestation remained loco-regional, radiotherapy (RT) (total dose of 20 Gy in 10 fractions) was initiated. Conclusion The patient achieved a complete remission without any side effects. This case highlights that RT is a rational and relative mild local treatment option for patients with aggressive LCH affecting the bone and surrounding soft tissue. Show less
Kemps, P.G.; Picarsic, J.; Durham, B.H.; Helias-Rodzewicz, Z.; Hiemcke-Jiwa, L.; Bos, C. van den; ... ; Emile, J.F. 2022
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... Show moreALK-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. Show less
Kemps, P.G.; Picarsic, J.; Durham, B.H.; Helias-Rodzewicz, Z.; Hiemcke-Jiwa, L.; Bos, C. van den; ... ; Emile, J.F. 2021
ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in three infants with multisystemic disease involving the liver and hematopoietic system. This entity... Show moreALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in three 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 ALKrearrangements. 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 (seven and twelve 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-ERK, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, while 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, ten 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. Show less
Histiocytic disorders are a spectrum of rare diseases characterised by the accumulation of macrophage-, dendritic cell-, or monocyte-differentiated cells in various tissues and organs. The... Show moreHistiocytic disorders are a spectrum of rare diseases characterised by the accumulation of macrophage-, dendritic cell-, or monocyte-differentiated cells in various tissues and organs. The discovery of recurrent genetic alterations in many of these histiocytoses has led to their recognition as clonal neoplastic diseases. Moreover, the identification of the same somatic mutation in histiocytic lesions and peripheral blood and/or bone marrow cells from histiocytosis patients has provided evidence for systemic histiocytic neoplasms to originate from haematopoietic stem/progenitor cells (HSPCs). Here, we investigated associations between histiocytic disorders and additional haematological malignancies bearing the same genetic alteration(s) using the nationwide Dutch Pathology Registry. By searching on pathologist-assigned diagnostic terms for the various histiocytic disorders, we identified 4602 patients with a putative histopathological diagnosis of a histiocytic disorder between 1971 and 2019. Histiocytosis-affected tissue samples of 187 patients had been analysed for genetic alterations as part of routine molecular diagnostics, including from nine patients with an additional haematological malignancy. Among these patients, we discovered three cases with different histiocytic neoplasms and additional haematological malignancies bearing identical oncogenic mutations, including one patient with concomitantKRASp.A59E mutated histiocytic sarcoma and chronic myelomonocytic leukaemia (CMML), one patient with synchronousNRASp.G12V mutated indeterminate cell histiocytosis and CMML, and one patient with subsequentNRASp.Q61R mutated Erdheim-Chester disease and acute myeloid leukaemia. These cases support the existence of a common haematopoietic cell-of-origin in at least a proportion of patients with a histiocytic neoplasm and additional haematological malignancy. In addition, they suggest that driver mutations in particular genes (e.g.N/KRAS) may specifically predispose to the development of an additional clonally related haematological malignancy or secondary histiocytic neoplasm. Finally, the putative existence of derailed multipotent HSPCs in these patients emphasises the importance of adequate (bone marrow) staging, molecular analysis and long-term follow-up of all histiocytosis patients. Show less
Langerhans Cell Histiocytosis (LCH) is a neoplastic disorder of hematopoietic origin characterized by inflammatory lesions containing clonal histiocytes (LCH-cells) intermixed with various immune... Show moreLangerhans Cell Histiocytosis (LCH) is a neoplastic disorder of hematopoietic origin characterized by inflammatory lesions containing clonal histiocytes (LCH-cells) intermixed with various immune cells, including T cells. In 50-60% of LCH-patients, the somatic BRAF(V600E) driver mutation, which is common in many cancers, is detected in these LCH-cells in an otherwise quiet genomic landscape. Non-synonymous mutations like BRAF(V600E) can be a source of neoantigens capable of eliciting effective antitumor CD8(+) T cell responses. This requires neopeptides to be stably presented by Human Leukocyte Antigen (HLA) class I molecules and sufficient numbers of CD8(+) T cells at tumor sites. Here, we demonstrate substantial heterogeneity in CD8(+) T cell density in n = 101 LCH-lesions, with BRAF(V600E) mutated lesions displaying significantly lower CD8(+) T cell:CD1a(+) LCH-cell ratios (p = 0.01) than BRAF wildtype lesions. Because LCH-lesional CD8(+) T cell density had no significant impact on event-free survival, we investigated whether the intracellularly expressed BRAF(V600E) protein is degraded into neopeptides that are naturally processed and presented by cell surface HLA class I molecules. Epitope prediction tools revealed a single HLA class I binding BRAF(V600E) derived neopeptide (KIGDFGLATEK), which indeed displayed strong to intermediate binding capacity to HLA-A*03:01 and HLA-A*11:01 in an in vitro peptide-HLA binding assay. Mass spectrometry-based targeted peptidomics was used to investigate the presence of this neopeptide in HLA class I presented peptides isolated from several BRAF(V600E) expressing cell lines with various HLA genotypes. While the HLA-A*02:01 binding BRAF wildtype peptide KIGDFGLATV was traced in peptides isolated from all five cell lines expressing this HLA subtype, KIGDFGLATEK was not detected in the HLA class I peptidomes of two distinct BRAF(V600E) transduced cell lines with confirmed expression of HLA-A*03:01 or HLA-A*11:01. These data indicate that the in silico predicted HLA class I binding and proteasome-generated neopeptides derived from the BRAF(V600E) protein are not presented by HLA class I molecules. Given that the BRAF(V600E) mutation is highly prevalent in chemotherapy refractory LCH-patients who may qualify for immunotherapy, this study therefore questions the efficacy of immune checkpoint inhibitor therapy in LCH. Show less
Halteren, A. van; Kemps, P.G.; Zondag, T.C.E.; Steenwijk, E.C.; Eijk, R. van; Lang, V.; ... ; Bos, C. van den 2017
