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 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.Molecular tumour pathology - and tumour genetic

Infectious complications in children with malignant bone tumors: a multicenter nationwide study

Krzysztof Czyzewski,1 Przemyslaw Galazka,2 Patrycja Zalas-Wiecek,3 Olga Gryniewicz-Kwiatkowska,4 Agnieszka Gietka,4 Katarzyna Semczuk,5 Liliana Chelmecka-Wiktorczyk,6 Iwona Zak,7 Malgorzata Salamonowicz,8 Jowita Fraczkiewicz,8 Olga Zajac-Spychala,9 Ewa Bien,10 Marcin Plonowski,11 Pawel Wawrykow,12 Filip Pierlejewski,13 Zuzanna Gamrot,14 Zofia Malas,15 Weronika Stolpa,16 Jakub Musial,17 Jan Styczynski11Department of Pediatric Hematology and Oncology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland; 2Department of General and Oncological Surgery for Children and Adolescents, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland; 3Department of Microbiology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland; 4Department of Oncology, Children’s Memorial Health Institute, Warsaw, Poland; 5Department of Microbiology, Children’s Memorial Health Institute, Warsaw, Poland; 6Department of Pediatric Oncology and Hematology, University Children’s Hospital, Jagiellonian University, Collegium Medicum, Krakow, Poland; 7Department of Microbiology, University Children’s Hospital, Jagiellonian University, Collegium Medicum, Krakow, Poland; 8Department of Pediatric Stem Cell Transplantation, Hematology and Oncology, Medical University, Wroclaw, Poland; 9Department of Pediatric Oncology, Hematology and Transplantology, University of Medical Sciences, Poznan, Poland; 10Department of Pediatrics, Hematology and Oncology, Medical University, Gdansk, Poland; 11Department of Pediatric Oncology and Hematology, Medical University, Bialystok, Poland; 12Department of Pediatrics and Pediatric Oncology, Pomeranian Medical University, Szczecin, Poland; 13Department of Pediatric Oncology and Hematology, Medical University, Lodz, Poland; 14Division of Pediatric Hematology and Oncology, Chorzow City Hospital, Chorzow, Poland; 15Division of Pediatric Hematology and Oncology, Children Hospital, Olsztyn, Poland; 16Division of Pediatric Oncology, Hematology and Chemotherapy, Department of Pediatric, Silesian Medical University, Katowice, Poland; 17Department of Pediatric Oncohematology, Medical Faculty University of Rzeszow, Clinical Provincial Hospital No. 2, Rzeszow, PolandObjectives: The analysis of epidemiology, risk factors and outcome of infections in children with malignant bone tumors (MBT) undergoing chemotherapy.Methods: In this retrospective nationwide multicenter cross-sectional study, a total number of 126 children with MBT including 70 with Ewing sarcoma (ES) and 56 with osteosarcoma (OSA) were screened for infections over a period of 72 consecutive months.Results: The risk of infection was 7.15-fold higher in patients with ES as compared to the OSA group, especially concerning bacterial infections (4.1-fold increase risk). Bacterial infections occurred in 74.3% patients with ES and in 41.1% with OSA. The median time from diagnosis to first infection was 4.9 months. 33.0% of bacterial episodes were diagnosed as bloodstream (BSI), 31.1% as gastrointestinal tract, 30.1% as urinary tract infection. Infection-related mortality (IRM) from bacterial infection was 6% and 15% in ES and OSA patients, respectively. Cumulative incidence was 7.1% for invasive fungal disease and 6.3% for viral infections. The only significant risk factor for IRM was time to infection ≥5 months since the beginning of chemotherapy. All patients who have died from infection had BSI and were in neutropenia.Conclusions: Infections in the children with MBT in our study occurred with high frequency, especially in patients with ES. The most frequent were bacterial infections, while fungal and viral infections were episodic. Among the bacterial infections, bloodstream, urinary tract and gastrointestinal tract infections occurred with similar frequency. All deceased patients died due to BSI. Bacterial infection occurring ≥5 months since the beginning of chemotherapy was a risk factor for death.Keywords: infectious complications, risk factors analysis, Ewing sarcoma, osteosarcoma, malignant bone tumor, children &nbsp

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.NEUROPatholog

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