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Summary Background Mycosis fungoides (MF) and Sézary Syndrome (SS) are the most common cutaneous T‐cell lymphomas. MF/SS is accompanied by considerable morbidity from pain, itching and disfigurement. Aim To identify factors associated with poorer health‐related quality of life (HRQoL) in patients newly diagnosed with MF/SS. Methods Patients enrolled into Prospective Cutaneous Lymphoma International Prognostic Index (PROCLIPI; an international observational study in MF/SS) had their HRQoL assessed using the Skindex‐29 questionnaire. Skindex‐29 scores were analysed in relation to patient‐ and disease‐specific characteristics. Results The study population consisted of 237 patients [60·3% male; median age 60 years, (interquartile range 49–70)], of whom 179 had early MF and 58 had advanced MF/SS. In univariate analysis, HRQoL, as measured by Skindex‐29, was worse in women, SS, late‐stage MF, those with elevated lactate dehydrogenase, alopecia, high modified Severity Weighted Assessment Tool and confluent erythema. Linear regression models only identified female gender (β = 8·61; P = 0·003) and alopecia (β = 9·71, P = 0·02) as independent predictors of worse global HRQoL. Item‐level analysis showed that the severe impairment in symptoms [odds ratio (OR) 2·14, 95% confidence interval (CI) 1·19–3·89] and emotions (OR 1·88, 95% CI 1·09–3·27) subscale scores seen in women was caused by more burning/stinging, pruritus, irritation and greater feelings of depression, shame, embarrassment and annoyance with their diagnosis of MF/SS. Conclusions HRQoL is significantly more impaired in newly diagnosed women with MF/SS and in those with alopecia. As Skindex‐29 does not include existential questions on cancer, which may cause additional worry and distress, a comprehensive validated cutaneous T‐cell lymphoma‐specific questionnaire is urgently needed to more accurately assess disease‐specific HRQoL in these patients. What's already known about this topic? Cross‐sectional studies of mixed populations of known and newly diagnosed patients with mycosis fungoides (MF)/Sézary syndrome (SS) have shown significant impairment in health‐related quality of life (HRQoL). Previous studies on assessing gender‐specific differences in HRQoL in MF/SS are conflicting. More advanced‐stage disease and pruritus is associated with poorer HRQoL in patients with MF/SS. What does this study add? This is the first prospective study to investigate HRQoL in a homogenous group of newly diagnosed patients with MF/SS. In patients newly diagnosed with MF/SS, HRQoL is worse in women and in those with alopecia and confluent erythema. MF/SS diagnosis has a multidimensional impact on patient HRQoL, including a large burden of cutaneous symptoms, as well as a negative impact on emotional well‐being.

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.

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