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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 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 (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.

We describe 2 previously healthy children who suffered disabling arterial ischemic strokes because of acute intracranial large vessel occlusion within 3 to 4 weeks of coronavirus disease 2019 (COVID-19) infection. Both children presented from communities with high COVID-19 case rates in the Southwest United States. An 8-year-old American Indian girl experienced severe iron deficiency anemia requiring blood transfusion and presented with bilateral middle cerebral artery (MCA) distribution strokes 3 weeks later. She underwent emergent mechanical thrombectomy of the left MCA with successful clot retrieval but experienced reocclusion of that artery 5 hours after intervention. She also had evidence of cerebral arteritis on catheter angiography and vessel wall imaging, and clot pathology revealed recently formed, unorganized platelet- and fibrin-rich thrombus with sparse clusters of erythrocytes, degenerated histiocytes, few eosinophils, and rare neutrophils. A 16-year old African American boy demonstrated evidence of arteritis on brain magnetic resonance angiography and serological markers of cardiac and renal injury accompanied by positive lupus anticoagulant antibodies. The children described in this report express clinical features inconsistent with focal cerebral arteriopathy, including elevated markers of systemic inflammation in both bilateral MCA strokes in one case and multiple organ system dysfunction in the other case. Neither patient fulfilled criteria for multisystem inflammatory syndrome in children, given absence of fever. These cases illustrate that systemic postinfectious arteritis with cerebrovascular involvement may complicate COVID-19 infection in previously healthy school-aged children, and their presentations may overlap but not fulfill criteria for multisystem inflammatory syndrome in children or focal cerebral arteriopathy.

The antifungal activity of aqueous extract of Cannabis sativa, Parthenium hysterophorus, Urtica dioeca, Polystichum squarrosum and Adiantum venustum was investigated against Alternaria solani, Alternaria zinniae, Curvularia lunata, Rhizoctonia solani and Fusarium oxysporum at different concentrations (5, 10, 15 and 20%). At 20%, maximum antifungal potential was observed with the extracts of C. sativa, which recorded excellent inhibitory activity against C. lunata (100%), A. zinniae (59.68%), followed by leaf extract of P. hysterophorus (50%) against A. solani. The application of botanical extracts for disease management could be less expensive, easily available, non-polluting and eco-friendly.

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