Histologic characterization of paediatric mesenchymal neoplasms treated with kinase-targeted therapy.

AIMS: Recurrent alterations involving receptor tyrosine or cytoplasmic kinase genes have been described in soft-tissue neoplasms such as infantile fibrosarcoma (IFS) and inflammatory myofibroblastic tumour (IMT). Recent trials and regulatory approvals for targeted inhibitors against the kinase domains of these oncoproteins have allowed for increased use of targeted therapies. We aimed to characterize the histologic features of paediatric mesenchymal neoplasms with kinase alterations treated with targeted inhibitors. METHODS AND RESULTS: Eight patients with tyrosine kinase-altered mesenchymal neoplasms with pre- and posttreatment samples were identified. Tumours occurred in five females and three males with a median age at presentation of 6.5 years. Tumour sites were bone/somatic soft-tissue (n = 5) and viscera (n = 3). Pretreatment diagnoses were: IMT (n = 3), epithelioid inflammatory myofibroblastic sarcoma (n = 1), and descriptive diagnoses (n = 4) such as "kinase-driven spindle cell tumor." Fusions identified were ETV6::NTRK3 (n = 2), TPM3::NTRK1, SEPT7::BRAF, TFG::ROS1, KLC1::ALK, RANBP2::ALK, and MAP4::RAF1. Patients were treated with larotrectinib (n = 3), ALK or ALK/ROS1 inhibitors (n = 3), and MEK inhibitors (n = 2). Posttreatment tumours exhibited a striking decrease in cellularity (7/8) and the presence of collagenous stroma (7/8) with extensive glassy hyalinization (5/8). In two cases, abundant coarse or psammomatous calcifications were seen and in one case prominent perivascular hyalinization was noted. Residual viable tumour was seen in 3/8 cases (<5% in one case, and >75% in 2/8 cases). CONCLUSION: Mesenchymal neoplasms with tyrosine kinase alterations treated with targeted inhibitors show a pathologic response, which includes decreased cellularity and stromal hyalinization. The presence of these features may be helpful in assessing tumour response after targeted therapy.

Recurrent RET gene fusions in paediatric spindle mesenchymal neoplasms.

AIMS: The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of so-called 'infantile fibrosarcoma' has expanded to include tumours with NTRK, BRAF and MET gene fusions. RET-rearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET-rearranged paediatric spindle cell tumours with fusion partners MYH10, KIAA1217 and CLIP2. METHODS AND RESULTS: The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients' ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high-power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy. CONCLUSIONS: Our findings help to define RET-rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.

Delirium in the pediatric hematology, oncology, and bone marrow transplant population.

BACKGROUND: Delirium affects 10% to 30% of patients in pediatric intensive care units (PICU) and is associated with increased length of stay and prolonged late sequela. There are no prospective trials evaluating delirium in the pediatric hematology, oncology, and bone marrow transplant (PHO) population. Hypothesizing that delirium is underrecognized in this population, our study aimed to identify the prevalence of delirium in hospitalized PHO patients and associated risk factors. PROCEDURE: PHO and PICU nurses were trained to use the Cornell Assessment for Pediatric Delirium and to record scores once every 12-hour shift. Predetermined demographic and clinical variables were collected daily on all hospitalized PHO patients during the year-long prospective study. RESULTS: Prior to initiating routine delirium screening, 1.1% of PHO admissions and 2.4% of unique patients had delirium mentioned in a progress note. This study included 807 consecutive admissions: 671 oncology, 49 hematology, and 87 bone marrow transplant (BMT) hospitalizations among 223 unique PHO patients. The prevalence of delirium among hospitalizations was 5% and among unique patients was 13%. Among BMT hospitalizations, the prevalence was 23%. Multiple logistic regression identified significant association of delirium with increased length of stay, admission to the BMT service, patient location (PICU vs PHO unit), benzodiazepine, opioid, and anticholinergic administration. CONCLUSIONS: Before routine screening, delirium was underrecognized in this PHO-hospitalized population. Patients at highest risk had prolonged hospital stays, PICU admissions, BMT, and/or frequent use of benzodiazepines, opioids, or anticholinergics. Routine screening is feasible and may improve our recognition of delirium.

Transplantation-Associated Altered Mentation and Encephalopathy: A New Classification for Acute Neurocognitive Changes Associated with Hematopoietic Cell Transplantation from the ASTCT Committee on Practice Guidelines.

Acute encephalopathy, manifesting clinically as delirium, is a common but often unrecognized complication of hematopoietic cell transplantation (HCT). Delirium can occur in patients of any age and is observed after autologous or allogeneic HCT. Although delirium has been studied primarily during initial HCT hospitalizations in recipients of myeloablative conditioning, recent investigations have identified delirium later post-transplantation and in recipients of reduced-intensity conditioning. Acute encephalopathy can be driven by infectious complications, medications, tissue damage, and/or organ dysfunction. Altered consciousness, either mild or profound, is often its only clinical manifestation. Identifying delirium is essential to overall HCT care, because patients who experience delirium have longer hospitalization and recovery times and are at risk for other poor post-HCT outcomes. Given the critical nature of this common complication and the ongoing expansion of HCT for more vulnerable populations, the American Society of Transplantation and Cellular Therapy (ASTCT) recommends intensifying research into post-HCT cognitive changes and establishing standardized definitions that encompass the full spectrum of altered consciousness for clinical care purposes and to provide benchmark endpoints for future research studies. To capture a range of acute neurocognitive changes specifically found in HCT patients (often referred to as acute encephalopathy), the ASTCT proposes a new diagnosis, transplantation-associated altered mentation and encephalopathy (TAME). The TAME diagnosis includes HCT patients who meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for delirium and those with acute neurocognitive changes who do not meet all the DSM-5 criteria for delirium (subsyndromal delirium). Early TAME is defined as occurring during conditioning or ≤100 days post-HCT, whereas late TAME occurs >100 days post-HCT in patients with additional HCT-related complications. This manuscript establishes clear diagnostic criteria and discusses factors that can potentially impact the development of TAME, as well as the workup and management of TAME.