A transthalamic pathway crucial for perception.

Perception is largely supported by cortical processing that involves communication among multiple areas, typically starting with primary sensory cortex and then involving higher order cortices. This communication is served in part by transthalamic (cortico-thalamo-cortical) pathways, which ubiquitously parallel direct corticocortical pathways, but their role in sensory processing has largely remained unexplored. Here, we suggest that transthalamic processing propagates task-relevant information required for correct sensory decisions. Using optogenetics, we specifically inhibited the pathway at its synapse in higher order somatosensory thalamus of mice performing a texture-based discrimination task. We concurrently monitored the cellular effects of inhibition in primary or secondary cortex using two-photon calcium imaging. Inhibition severely impaired performance despite intact direct corticocortical projections, thus challenging the purely corticocentric map of perception. Interestingly, the inhibition did not reduce overall cell responsiveness to texture stimulation in somatosensory cortex, but rather disrupted the texture selectivity of cells, a discriminability that develops over task learning. This discriminability was more disrupted in the secondary than primary somatosensory cortex, emphasizing the feedforward influence of the transthalamic route. Transthalamic pathways may therefore act to deliver performance-relevant information to higher order cortex and are underappreciated hierarchical pathways in perceptual decision-making.

Convergence of inputs from the basal ganglia with layer 5 of motor cortex and cerebellum in mouse motor thalamus.

A key to motor control is the motor thalamus, where several inputs converge. One excitatory input originates from layer 5 of primary motor cortex (M1L5), while another arises from the deep cerebellar nuclei (Cb). M1L5 terminals distribute throughout the motor thalamus and overlap with GABAergic inputs from the basal ganglia output nuclei, the internal segment of the globus pallidus (GPi), and substantia nigra pars reticulata (SNr). In contrast, it is thought that Cb and basal ganglia inputs are segregated. Therefore, we hypothesized that one potential function of the GABAergic inputs from basal ganglia is to selectively inhibit, or gate, excitatory signals from M1L5 in the motor thalamus. Here, we tested this possibility and determined the circuit organization of mouse (both sexes) motor thalamus using an optogenetic strategy in acute slices. First, we demonstrated the presence of a feedforward transthalamic pathway from M1L5 through motor thalamus. Importantly, we discovered that GABAergic inputs from the GPi and SNr converge onto single motor thalamic cells with excitatory synapses from M1L5. Separately, we also demonstrate that, perhaps unexpectedly, GABAergic GPi and SNr inputs converge with those from the Cb. We interpret these results to indicate that a role of the basal ganglia is to gate the thalamic transmission of M1L5 and Cb information to cortex.

A Reconsideration of the Core and Matrix Classification of Thalamocortical Projections.

In 1998, Jones suggested a classification of thalamocortical projections into core and matrix divisions (Jones, 1998). In this classification, core projections are specific, topographical, innervate middle cortical layers, and serve to transmit specific information to the cortex for further analysis; matrix projections, in contrast, are diffuse, much less topographic, innervate upper layers, especially Layer 1, and serve a more global, modulatory function, such as affecting levels of arousal. This classification has proven especially influential in studies of thalamocortical relationships. Whereas it may be the case that a clear subset of thalamocortical connections fit the core motif, since they are specific, topographic, and innervate middle layers, we argue that there is no clear evidence for any single class that encompasses the remainder of thalamocortical connections as is claimed for matrix. Instead, there is great morphological variation in connections made by thalamocortical projections fitting neither a core nor matrix classification. We thus conclude that the core/matrix classification should be abandoned, because its application is not helpful in providing insights into thalamocortical interactions and can even be misleading. As one example of the latter, recent suggestions indicate that core projections are equivalent to first-order thalamic relays (i.e., those that relay subcortical information to the cortex) and matrix to higher-order relays (i.e., those that relay information from one cortical area to another), but available evidence does not support this relationship. All of this points to a need to replace the core/matrix grouping with a more complete classification of thalamocortical projections.

Convergence of inputs from the basal ganglia with layer 5 of motor cortex and cerebellum in mouse motor thalamus.

A key to motor control is the motor thalamus, where several inputs converge. One excitatory input originates from layer 5 of primary motor cortex (M1L5), while another arises from the deep cerebellar nuclei (Cb). M1L5 terminals distribute throughout the motor thalamus and overlap with GABAergic inputs from the basal ganglia output nuclei, the internal segment of the globus pallidus (GPi) and substantia nigra pars reticulata (SNr). In contrast, it is thought that Cb and basal ganglia inputs are segregated. Therefore, we hypothesized that one potential function of the GABAergic inputs from basal ganglia is to selectively inhibit, or gate, excitatory signals from M1L5 in the motor thalamus. Here, we tested this possibility and determined the circuit organization of mouse (both sexes) motor thalamus using an optogenetic strategy in acute slices. First, we demonstrated the presence of a feedforward transthalamic pathway from M1L5 through motor thalamus. Importantly, we discovered that GABAergic inputs from the GPi and SNr converge onto single motor thalamic cells with excitatory synapses from M1L5 and, unexpectedly, Cb as well. We interpret these results to indicate that a role of the basal ganglia is to gate the thalamic transmission of M1L5 and Cb information to cortex.

Alpha cell receptor for advanced glycation end products associate with glucagon expression in type 1 diabetes.

Hypoglycemia in type 1 diabetes associates with changes in the pancreatic islet α cells, where the receptor for advanced glycation end products (RAGE) is highly expressed. This study compared islet RAGE expression in donors without diabetes, those at risk of, and those with type 1 diabetes. Laser-dissected islets were subject to RNA bioinformatics and adjacent pancreatic tissue were assessed by confocal microscopy. We found that islets from type 1 diabetes donors had differential expression of the RAGE gene (AGER) and its correlated genes, based on glucagon expression. Random forest machine learning revealed that AGER was the most important predictor for islet glucagon levels. Conversely, a generalized linear model identified that glucagon expression could be predicted by expression of RAGE signaling molecules, its ligands and enzymes that create or clear RAGE ligands. Confocal imaging co-localized RAGE, its ligands and signaling molecules to the α cells. Half of the type 1 diabetes cohort comprised of adolescents and a patient with history of hypoglycemia-all showed an inverse relationship between glucagon and RAGE. These data confirm an association between glucagon and islet RAGE, its ligands and signaling pathways in type 1 diabetes, which warrants functional investigation into a role for RAGE in hypoglycemia.

Profile of and risk factors for early unplanned readmissions in patients with acute necrotizing pancreatitis.

INTRODUCTION: Acute necrotizing pancreatitis (ANP) complicates up to 15% of acute pancreatitis cases. ANP has historically been associated with a significant risk for readmission, but there are currently no studies exploring factors that associate with risk for unplanned, early (<30-day) readmissions in this patient population. METHODS: We performed a retrospective review of all consecutive patients presenting to hospitals in the Indiana University (IU) Health system with pancreatic necrosis between December 2016 and June 2020. Patients younger than 18 years of age, without confirmed pancreatic necrosis and those that suffered in-hospital mortality were excluded. Logistic regression was performed to identify potential predictors of early readmission in this group of patients. RESULTS: One hundred and sixty-two patients met study criteria. 27.7% of the cohort was readmitted within 30-days of index discharge. The median time to readmission was 10 days (IQR 5-17 days). The most frequent reason for readmission was abdominal pain (75.6%), followed by nausea and vomiting in (35.6%). Discharge to home was associated with 93% lower odds of readmission. We found no additional clinical factors that predicted early readmission. CONCLUSION: Patients with ANP have a significant risk for early (<30 days) readmission. Direct discharge to home, rather than short or long-term rehabilitation facilities, is associated with lower odds of early readmission. Analysis was otherwise negative for independent, clinical predictors of early unplanned readmissions in ANP.

A transthalamic pathway crucial for perception.

Perception arises from activity between cortical areas, first primary cortex and then higher order cortices. This communication is served in part by transthalamic (cortico-thalamo-cortical) pathways, which ubiquitously parallel direct corticocortical pathways, but their role in sensory processing has largely remained unexplored. Here, we show that the transthalamic pathway linking somatosensory cortices propagates task-relevant information required for correct sensory decisions. Using optogenetics, we specifically inhibited the pathway at its synapse in higher order somatosensory thalamus of mice performing a texture-based discrimination task. We concurrently monitored the cellular effects of inhibition in primary or secondary cortex using two-photon calcium imaging. Inhibition severely impaired performance despite intact direct corticocortical projections, thus challenging the purely corticocentric map of perception. Interestingly, the inhibition did not reduce overall cell responsiveness to texture stimulation in somatosensory cortex, but rather disrupted the texture selectivity of cells, a discriminability that develops over task learning. This discriminability was more disrupted in the secondary than primary somatosensory cortex, emphasizing the feedforward influence of the transthalamic route. Transthalamic pathways thus appear critical in delivering performance-relevant information to higher order cortex and are critical hierarchical pathways in perceptual decision-making.

Layer 5 of cortex innervates the thalamic reticular nucleus in mice.

Neurons in the thalamic reticular nucleus (TRN) are a primary source of inhibition to the dorsal thalamus and, as they are innervated in part by the cortex, are a means of corticothalamic regulation. Previously, cortical inputs to the TRN were thought to originate solely from layer 6 (L6), but we recently reported the presence of putative synaptic terminals from layer 5 (L5) neurons in multiple cortical areas in the TRN [J. A. Prasad, B. J. Carroll, S. M. Sherman, J. Neurosci. 40, 5785-5796 (2020)]. Here, we demonstrate with electron microscopy that L5 terminals from multiple cortical regions make bona fide synapses in the TRN. We further use light microscopy to localize these synapses relative to recently described TRN subdivisions and show that L5 terminals target the edges of the somatosensory TRN, where neurons reciprocally connect to higher-order thalamus, and that L5 terminals are scarce in the core of the TRN, where neurons reciprocally connect to first-order thalamus. In contrast, L6 terminals densely innervate both edge and core subregions and are smaller than those from L5. These data suggest that a sparse but potent input from L5 neurons of multiple cortical regions to the TRN may yield transreticular inhibition targeted to higher-order thalamus.

Soluble RAGE Prevents Type 1 Diabetes Expanding Functional Regulatory T Cells.

Type 1 diabetes is an autoimmune disease with no cure, where clinical translation of promising therapeutics has been hampered by the reproducibility crisis. Here, short-term administration of an antagonist to the receptor for advanced glycation end products (sRAGE) protected against murine diabetes at two independent research centers. Treatment with sRAGE increased regulatory T cells (Tregs) within the islets, pancreatic lymph nodes, and spleen, increasing islet insulin expression and function. Diabetes protection was abrogated by Treg depletion and shown to be dependent on antagonizing RAGE with use of knockout mice. Human Tregs treated with a RAGE ligand downregulated genes for suppression, migration, and Treg homeostasis (FOXP3, IL7R, TIGIT, JAK1, STAT3, STAT5b, CCR4). Loss of suppressive function was reversed by sRAGE, where Tregs increased proliferation and suppressed conventional T-cell division, confirming that sRAGE expands functional human Tregs. These results highlight sRAGE as an attractive treatment to prevent diabetes, showing efficacy and reproducibility at multiple research centers and in human T cells.

Conserved patterns of functional organization between cortex and thalamus in mice.

Higher-order thalamic nuclei contribute to sensory processing via projections to primary and higher cerebral cortical areas, but it is unknown which of their cortical and subcortical inputs contribute to their distinct output pathways. We used subpopulation specific viral strategies in mice to anatomically and physiologically dissect pathways of the higher-order thalamic nuclei of the somatosensory and visual systems (the posterior medial nucleus and pulvinar). Employing a complementary optogenetics and electrical stimulation strategy, we show that synapses in cortex from higher-order thalamus have functionally divergent properties in primary vs. higher cortical areas. Higher-order thalamic projections onto excitatory targets in S1 and V1 were weakly modulatory, while projections to S2 and higher visual areas were strong drivers of postsynaptic targets. Then, using transsynaptic tracing verified by optogenetics to map inputs to higher-order thalamus, we show that posterior medial nucleus cells projecting to S1 are driven by neurons in layer 5 of S1, S2, and M1 and that pulvinar cells projecting to V1 are driven by neurons in layer 5 of V1 and higher visual areas. Therefore, in both systems, layer 5 of primary and higher cortical areas drives transthalamic feedback modulation of primary sensory cortex through higher-order thalamus. These results highlight conserved organization that may be shared by other thalamocortical circuitry. They also support the hypothesis that direct corticocortical projections in the brain are paralleled by transthalamic pathways, even in the feedback direction, with feedforward transthalamic pathways acting as drivers, while feedback through thalamus is modulatory.

COVID-19 vaccination acceptability in the UK at the start of the vaccination programme: a nationally representative cross-sectional survey (CoVAccS - wave 2).

OBJECTIVES: Investigate factors associated with the intention to have the COVID-19 vaccination following initiation of the UK national vaccination programme. STUDY DESIGN: An online cross-sectional survey completed by 1500 adults (13th-15th January 2021). METHODS: Linear regression analyses were used to investigate associations between intention to be vaccinated for COVID-19 and sociodemographic factors, previous influenza vaccination, attitudes and beliefs about COVID-19 and COVID-19 vaccination and vaccination in general. Participants' main reasons for likely vaccination (non-)uptake were also solicited. RESULTS: 73.5% of participants (95% CI 71.2%, 75.7%) reported being likely to be vaccinated against COVID-19, 17.3% (95% CI 15.4%, 19.3%) were unsure, and 9.3% (95% CI 7.9%, 10.8%) reported being unlikely to be vaccinated. The full regression model explained 69.8% of the variance in intention. Intention was associated with: having been/intending to be vaccinated for influenza last winter/this winter; stronger beliefs about social acceptability of a COVID-19 vaccine; the perceived need for vaccination; adequacy of information about the vaccine; and weaker beliefs that the vaccine is unsafe. Beliefs that only those at serious risk of illness should be vaccinated and that the vaccines are just a means for manufacturers to make money were negatively associated with vaccination intention. CONCLUSIONS: Most participants reported being likely to get the COVID-19 vaccination. COVID-19 vaccination attitudes and beliefs are a crucial factor underpinning vaccine intention. Continued engagement with the public with a focus on the importance and safety of vaccination is recommended.

Integration of signals from different cortical areas in higher order thalamic neurons.

Higher order thalamic neurons receive driving inputs from cortical layer 5 and project back to the cortex, reflecting a transthalamic route for corticocortical communication. To determine whether or not individual neurons integrate signals from different cortical populations, we combined electron microscopy "connectomics" in mice with genetic labeling to disambiguate layer 5 synapses from somatosensory and motor cortices to the higher order thalamic posterior medial nucleus. A significant convergence of these inputs was found on 19 of 33 reconstructed thalamic cells, and as a population, the layer 5 synapses were larger and located more proximally on dendrites than were unlabeled synapses. Thus, many or most of these thalamic neurons do not simply relay afferent information but instead integrate signals as disparate in this case as those emanating from sensory and motor cortices. These findings add further depth and complexity to the role of the higher order thalamus in overall cortical functioning.

Cortical control of behavior and attention from an evolutionary perspective.

For animals to survive, they must interact with their environment, taking in sensory information and making appropriate motor responses. Early on during vertebrate evolution, this was accomplished with neural circuits located mostly within the spinal cord and brainstem. As the cerebral cortex evolved, it provided additional and powerful advantages for assessing environmental cues and guiding appropriate responses. Importantly, the cerebral cortex was added onto an already functional nervous system. Moreover, every cortical area, including areas traditionally considered sensory, provides input to the subcortical motor structures that are bottlenecks for driving action. These facts have important ramifications for cognitive aspects of motor control. Here we consider the evolution of cortical mechanisms for attention from the perspective of having to work through these subcortical bottlenecks. From this perspective, many features of attention can be explained, including the preferential engagement of some cortical areas at the cost of disengagement from others to improve appropriate behavioral responses.

Racial differences in overdose training, naloxone possession, and naloxone administration among clients and nonclients of a syringe services program.

OBJECTIVE: To evaluate racial (Black/White) differences in overdose response training and take-home naloxone (THN) possession and administration among clients and nonclients of the Baltimore syringe service program (SSP). METHODS: The study derived data from a cross-sectional survey of 263 (183 SSP clients, 80 nonclients) people who inject drugs (PWID). The study recruited SSP clients using targeted sampling and recruited nonclients through peer referral from April to November 2016. RESULTS: In our sample, 61% of the participants were Black, 42% were between the ages of 18 and 44, and 70% were males. SSP clients, regardless of race, were more likely to have received overdose response training than Black nonclients (Black clients AOR: 3.85, 95% CI: 1.88, 7.92; White clients AOR: 2.73, 95% CI: 1.29, 5.75). The study found no significant differences in overdose response training between Black and White nonclients. SSP clients and White nonclients were more likely to possess THN than Black nonclients (Black clients: AOR: 4.21, 95% CI: 2.00, 8.87; White clients: AOR: 3.54, 95% CI: 1.56, 8.04; White nonclients AOR: 4.49, 95% CI: 1.50,13.47). CONCLUSION: SSP clients were more likely to receive overdose response training than their nonclient peers who they referred to the study, illustrating the utility of SSPs in reaching PWID at high risk of overdose. We also observed that Black PWID, who did not access services at the SSP, were the least likely to possess THN, suggesting the need to employ outreach targeting Black PWID who do not access this central harm reduction intervention.

Complexation reduces nickel toxicity to purple sea urchin embryos (Strongylocentrotus purpuratus), a test of biotic ligand principles in seawater.

The potential for Ni toxicity in seawater is of concern because of mining and processing activities in coastal regions. Determining Ni speciation is vital to understanding and predicting Ni toxicity and for bioavailability-based nickel risk assessment. The goal of this study was to characterize the complexation of Ni in relation to toxicity using embryological development of purple sea urchin (S. purpuratus). It was predicted that free ion [Ni2+] would be a better predictor of toxicity than total dissolved Ni concentrations (NiD). Synthetic ligands with known logKf values (Ethylenediaminetetraacetic acid (EDTA), Nitrilotriacetic acid (NTA), tryptophan (TRP), glutamic acid (GA), histidine (HD), and citric acid (CA)) were used to test the assumptions of the biotic ligand model (BLM) for Ni in seawater. [NiD] was measured by graphite furnace atomic absorption spectroscopy (GFAAS) and Ni2+ was first quantified using the ion-exchange technique (IET) and then concentrations were measured by GFAAS; [Ni2+] was also estimated using aquatic geochemistry modelling software (Visual Minteq). The mean EC50 values for [NiD] in unmodified artificial seawater control was 3.6 µM (95% CI 3.0-4.5) [211 µg/L 95% CI 176-264] and the addition of ligands provided protection, up to 6.5-fold higher [NiD] EC50 for EDTA. Compared to the control, measured EC50 values based on total dissolved nickel were higher in the presence of ligands. As predicted by BLM theory, [Ni2+] was a better predictor of Ni toxicity with 17% variability in EDTA and CA media while there was 72% variability in the prediction of Ni toxicity with total dissolved Ni. The results of this research provide support for the application of BLM- based prediction models for estimating Ni impacts in seawater.

Safety and activity of vandetanib in combination with everolimus in patients with advanced solid tumors: a phase I study.

BACKGROUND: Preclinical studies suggest that combining vandetanib (VAN), a multi-tyrosine kinase inhibitor of rearranged during transfection (RET) proto-oncogene, vascular endothelial growth factor receptor (VEGFR), and epidermal growth factor receptor (EGFR), with everolimus (EV), a mammalian target of rapamycin (mTOR) inhibitor, may improve antitumor activity. We determined the safety, maximum tolerated dose (MTD), recommended phase II dose (RP2D), and dose-limiting toxicities (DLTs) of VAN + EV in patients with advanced solid cancers and the effect of combination therapy on cancer cell proliferation and intracellular pathways. PATIENTS AND METHODS: Patients with refractory solid tumors were enrolled in a phase I dose-escalation trial testing VAN (100-300 mg orally daily) + EV (2.5-10 mg orally daily). Objective responses were evaluated using RECIST v1.1. RET mutant cancer cell lines were used in cell-based studies. RESULTS: Among 80 patients enrolled, 72 (90%) patients were evaluable: 7 achieved partial response (PR) (10%) and 37 had stable disease (SD) (51%; duration range: 1-27 cycles). Clinical benefit (SD or PR ≥ 6 months) was observed in 26 evaluable patients [36%, 95% confidence intervals (CI) (25% to 49%)]. In 80 patients, median overall survival (OS) was 10.5 months [95% CI (8.5-16.1)] and median progression-free survival (PFS) 4.1 months [95% CI (3.4-7.3)]. Six patients (7.5%) experienced DLTs and 20 (25%) required dose modifications. VAN + EV was safe, with fatigue, rash, diarrhea, and mucositis being the most common toxicities. In cell-based studies, combination therapy was superior to monotherapy at inhibiting cancer cell proliferation and intracellular signaling. CONCLUSIONS: The MTDs and RP2Ds of VAN + EV are 300 mg and 10 mg, respectively. VAN + EV combination is safe and active in refractory solid tumors. Further investigation is warranted in RET pathway aberrant tumors.

The PEARL study: a prospective two-group pilot PrEP promotion intervention for cisgender female sex workers living in Baltimore, MD, U.S.

HIV remains elevated among female sex workers (FSW) globally, with a number of structural (e.g., poverty, access to care) factors driving these persistently high rates. Pre-exposure prophylaxis (PrEP), a user-controlled prevention method, is a promising means of empowering vulnerable populations to protect themselves and enhance agency. Yet there is a dearth of PrEP research and interventions targeting cisgender women in the United States, and even fewer aimed to reach FSW. We developed and implemented a multifaceted PrEP pilot intervention, the Promoting Empowerment And Risk Reduction (PEARL) study, to meet this gap. This paper describes the development process and nature of a community-informed intervention for tenofovir/emticitrabine (TDF/FTC) pre-exposure prophylaxis engagement among street-based cisgender FSW in Baltimore, Maryland, U.S. In the course of the study's implementation, structural, programmatic, and medical barriers have already posed significant barriers to full engagement. PEARL implemented a number of strategies in an effort to counter barriers and facilitate increased success of PrEP uptake and maintenance. The study will provide critical insights into the nature of intervention components that could help FSW to initiate PrEP and reduce PrEP care cascade gaps.

ASO Author Reflections: Indolent Growth and Small Bowel Neuroendocrine Tumor Management.

Surgical treatment is central to management of small bowel neuroendocrine tumors (SBNETs). Current controversies include whether to resect asymptomatic primary tumors in the setting of unresectable metastases, the role of minimally invasive surgery, and how best to incorporate/sequence medical treatments. Low SBNET incidence, long event-times, and variability in disease burden, surgical technique, and institutional treatment preferences remain obstacles to conducting randomized surgical trials for SBNETs. With increasing referral of these patients to high-volume centers, cooperation between experienced SBNET clinicians should allow design of high-quality randomized trials to test new treatments and answer key questions.

An Initiative to Reduce Preterm Infants Pre-discharge Growth Failure Through Time-specific Feeding Volume Increase.

Very low birth weight infants often demonstrate poor postnatal longitudinal growth, which negatively impacts survival rates and long-term health outcomes. Improving extrauterine growth restriction (EUGR) among extremely premature infants has become a significant focus of quality improvement initiatives. Prior efforts in the University of Massachusetts Memorial Medical Center neonatal intensive care unit were unsuccessful in improving the EUGR rate at discharge. METHODS: The primary aim of this initiative was to improve EUGR at discharge [defined as weight less than 10th percentile for postmenstrual age (PMA)] for infants born ≤32 0/7 weeks from a baseline of 25% to 20% by June 2019. We excluded all small for gestational age infants due to the limitation in the EUGR definition. A multidisciplinary team implemented evidence-based nutritional guideline changes using the Institute of Healthcare Improvement methods. The most notable change was the time-specific feeding volume advancement that increased the goal feeding volume between 31 0/7 and 34 0/7 weeks PMA from 150-160 to 170-180 milliliters per kilogram per day. The team monitored nutritional intake, weight, necrotizing enterocolitis (NEC), bronchopulmonary dysplasia (BPD), and length of stay (LOS). RESULTS: The EUGR rate improved from 25% to 12% after initiation of increased time-specific, enteral feeding guidelines at 31-34 weeks PMA. NEC rate, BPD rate, and LOS remained unchanged throughout the initiative. CONCLUSIONS: By implementing a time-specific volume increase guideline from 31 0/7 to 34 0/7 weeks PMA, the EUGR rate improved from baseline of 25% to 12% without increasing NEC rate, BPD rate, and LOS.

Should we be imaging lymph nodes at initial diagnosis of early-stage mycosis fungoides? Results from the PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) international study.

BACKGROUND: Early-stage mycosis fungoides (MF) includes involvement of dermatopathic lymph nodes (LNs) or early lymphomatous LNs. There is a lack of unanimity among current guidelines regarding the indications for initial staging imaging in early-stage presentation of MF in the absence of enlarged palpable LNs. OBJECTIVES: To investigate how often imaging is performed in patients with early-stage presentation of MF, to assess the yield of LN imaging, and to determine what disease characteristics promoted imaging. METHODS: A review of clinicopathologically confirmed newly diagnosed patients with cutaneous patch/plaque (T1/T2) MF from PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) data. RESULTS: PROCLIPI enrolled 375 patients with stage T1/T2 MF: 304 with classical MF and 71 with folliculotropic MF. Imaging was performed in 169 patients (45%): 83 with computed tomography, 18 with positron emission tomography-computed tomography and 68 with ultrasound. Only nine of these (5%) had palpable enlarged (≥ 15 mm) LNs, with an over-representation of plaques, irrespectively of the 10% body surface area cutoff that distinguishes T1 from T2. Folliculotropic MF was not more frequently imaged than classical MF. Radiologically enlarged LNs (≥ 15 mm) were detected in 30 patients (18%); only seven had clinical lymphadenopathy. On multivariate analysis, plaque presentation was the sole parameter significantly associated with radiologically enlarged LNs. Imaging of only clinically enlarged LNs upstaged 4% of patients (seven of 169) to at least IIA, whereas nonselective imaging upstaged another 14% (24 of 169). LN biopsy, performed in eight of 30 patients, identified N3 (extensive lymphomatous involvement) in two and N1 (dermatopathic changes) in six. CONCLUSIONS: Physical examination was a poor determinant of LN enlargement or involvement. Presence of plaques was associated with a significant increase in identification of enlarged or involved LNs in patients with early-stage presentation of MF, which may be important when deciding who to image. Imaging increases the detection rate of stage IIA MF, and identifies rare cases of extensive lymphomatous nodes, upstaging them to advanced-stage IVA2.