Probing the role of magnetic fields in star-forming filaments: NIKA2-Pol commissioning results toward OMC-1

Dust polarization observations are a powerful, practical tool to probe the geometry (and to some extent, the strength) of magnetic fields in starforming regions. In particular, Planck polarization data have revealed the importance of magnetic fields on large scales in molecular clouds. However, due to insufficient resolution, Planck observations are unable to constrain the B-field geometry on prestellar and protostellar scales. The high angular resolution of 11.7 arcsec provided by NIKA2-Pol 1.15 mm polarimetric imaging, corresponding to 0.02 pc at the distance of the Orion molecular cloud (OMC), makes it possible to advance our understanding of the B-field morphology in star-forming filaments and dense cores (IRAM 30m large program B-FUN). The commissioning of the NIKA2-Pol instrument has led to several challenging issues, in particular, the instrumental polarization or intensity-to-polarization “leakage” effect. In the present paper, we illustrate how this effect can be corrected for, leading to reliable exploitable data in a structured, extended source such as OMC-1. We present a statistical comparison between NIKA2-Pol and SCUBA2-Pol2 results in the OMC-1 region. We also present tentative evidence of local pinching of the B-field lines near Orion-KL, in the form of a new small-scale hourglass pattern, in addition to the larger-scale hourglass already seen by other instruments such as Pol2.

Observations with KIDs Interferometer Spectrum Survey (KISS)

We describe the preliminary on-sky results of the KIDs Interferometer Spectrum Survey (KISS), a spectral imager with a 1 deg field of view (FoV). The instrument operates in the range 120–180 GHz from the 2.25m Q-U-I JOint TEnerife telescope in Teide Observatory (Tenerife, Canary Islands), at 2 395m altitude above sea level. Spectra at low resolution, up to 1.45 GHz, are obtained using a fast (3.72 Hz mechanical frequency) Fourier transform spectrometer, coupled to a continuous dilution cryostat with a stabilized temperature of 170mK that hosts two 316-pixel arrays of lumped-element kinetic inductance detectors. KISS generates more than 3 000 spectra per second during observations and represents a pathfinder to demonstrate the potential for spectral mapping with large FoV.We give an overall description of the spectral mapping paradigm and we present recent results from observations, in this paper.

Multi-probe analysis of the galaxy cluster CL J1226.9+3332: Hydrostatic mass and hydrostatic-to-lensing bias

We present a multi-probe analysis of the well-known galaxy cluster CL J1226.9+3332 as a proof of concept for multi-wavelength studies within the framework of the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ). CL J1226.9+3332 is a massive and high redshift (z = 0.888) cluster that has already been observed at several wavelengths. A joint analysis of the thermal SZ (tSZ) effect at millimeter wavelength with the NIKA2 camera and in X-ray with the XMM-Newton satellite permits the reconstruction of the cluster’s thermodynamical properties and mass assuming hydrostatic equilibrium. We test the robustness of our mass estimates against different definitions of the data analysis transfer function. Using convergence maps reconstructed from the data of the CLASH program we obtain estimates of the lensing mass, which we compare to the estimated hydrostatic mass. This allows us to measure the hydrostatic-to-lensing mass bias and the associated systematic effects related to the NIKA2 measurement. We obtain M500HSE = (7:65 ± 1:03) × 1014M⊙ and M500lens = (7:35 ± 0:65) × 1014M⊙, which implies a HSE-to-lensing bias consistent with 0 within 20%.

Exploring the millimetre emission in nearby galaxies: Analysis of the edge-on galaxy NGC 891

New observations of the edge-on galaxy NGC 891, at 1.15 and 2mm obtained with the IRAM 30-m telescope and the NIKA2 camera, within the framework of the IMEGIN (Interpreting the Millimetre Emission of Galaxies with IRAM and NIKA2) Large Program, are presented in this work. By using multiwavelength maps (from the mid-IR to the cm wavelengths) we perform SED fitting in order to extract the physical properties of the galaxy on both global and local (~kpc) scales. For the interpretation of the observations we make use of a state-of-the-art SED fitting code, HerBIE (HiERarchical Bayesian Inference for dust Emission). The observations indicate a galaxy morphology, at mm wavelengths, similar to that of the cold dust emission traced by submm observations and to that of the molecular gas. The contribution of the radio emission at the NIKA2 bands is very small (negligible at 1.15 mm and ~ 10% at 2 mm) while it dominates the total energy budget at longer wavelengths (beyond 5 mm). On local scales, the distribution of the free-free emission resembles that of the dust thermal emission while the distribution of the synchrotron emission shows a deficiency along the major axis of the disc of the galaxy.

The NIKA2 Sunyaev-Zeldovich Large Program: Precise galaxy cluster physics for an accurate cluster-based cosmology

The NIKA2 Guaranteed-Time SZ Large Program (LPSZ) is dedicated to the high-angular resolution SZ mapping of a representative sample of 45 SZ-selected galaxy clusters drawn from the catalogues of the Planck satellite, or of the Atacama Cosmology Telescope. The LPSZ sample spans a mass range from 3 to 11 × 1014M⊙ and a redshift range from 0:5 to 0:9, extending to higher redshift and lower mass the previous samples dedicated to the cluster mass calibration and universal properties estimation. The main goals of the LPSZ are the measurement of the average radial profile of the ICM pressure up to R500 by combining NIKA2 with Planck or ACT data, and the estimation of the scaling law between the SZ observable and the mass using NIKA2, XMM-Newton and Planck/ACT data. Furthermore, combining LPSZ data with existing or forthcoming public data in lensing, optical/NIR or radio domains, we will build a consistent picture of the cluster physics and further gain knowledge on the mass estimate as a function of the cluster morphology and dynamical state.

We give an overview of the LPSZ, present recent results and discuss the future implication for cosmology with galaxy clusters.

Searching for high-z DSFGs with NIKA2 and NOEMA

As the possible progenitors of passive galaxies at z=2-3, dusty starforming galaxies (DSFGs) at z>4 provide a unique perspective to study the formation, assembly, and early quenching of massive galaxies in the early Universe. The extreme obscuration in optical-IR makes (sub)mm spectral scans the most universal and unbiased way to confirm/exclude the high-z nature of candidate dusty star-forming galaxies. We present here the status of the NIKA2 Cosmological Legacy Survey (N2CLS), which is the deepest wide-area singledish survey in the millimeter searching for high-z DSFGs. We also introduce a joint-analysis method to effciently search for the spectroscopic redshift of high-z DSFGs with noisy spectra and photometric data and present its success in identifying the redshift of DSFGs found in NIKA2 science verification data.

Galactic star formation with NIKA2 (GASTON): Filament convergence and its link to star formation

In the past decade filaments have been recognised as a major structural element of the interstellar medium, the densest of these filaments hosting the formation of most stars. In some star-forming molecular clouds converging networks of filaments, also known as hub filament systems, can be found. These hubs are believed to be preferentially associated to massive star formation. As of today, there are no metrics that allow the systematic quantification of a filament network convergence. Here, we used the IRAM 30m NIKA2 observations of the Galactic plane from the GASTON large programme to systematically identify filaments and produce a filament convergence parameter map. We use such a map to show that: i. hub filaments represent a small fraction of the global filament population; ii. hubs host, in proportion, more massive and more luminous compact sources that non-hubs; iii. hub-hosting clumps are more evolved that non-hubs; iv. no discontinuities are observed in the properties of compact sources as a function of convergence parameter. We propose that the rapid global collapse of clumps is responsible for (re)organising filament networks into hubs and, in parallel, enhancing the mass growth of compact sources.

PSZ2 G091: A massive double cluster at z ~ 0.822 observed by the NIKA2 camera

PSZ2 G091.83+26.11 is a massive galaxy cluster with M500 = 7:43 × 1014M⊙ at z = 0:822. This object exhibits a complex morphology with a clear bimodality observed in X-rays. However, it was detected and analysed in the Planck sample as a single, spherical cluster following a universal profile [1]. This model can lead to miscalculations of thermodynamical quantities, like the pressure profile. As future multiwavelength cluster experiments will detect more and more objects at higher redshifts (where we expect the fraction of merging objects to be higher), it is crucial to quantify this systematic effect. In this work, we use high-resolution observations of PSZ2 G091.83+26.11 by the NIKA2 camera to integrate the morphological characteristics of the cluster in our modelling. This is achieved by fitting a two-halo model to the SZ image and then by reconstruction of the resulting projected pressure profile. We then compare these results with the spherical assumption.

CONCERTO at APEX: Installation and first phase of on-sky commissioning

CONCERTO (CarbON CII line in post-rEionisation and ReionisaTiOn) is a large field-of-view (FoV) spectro-imager that has been installed on the Cassegrain Cabin of Atacama Pathfinder EXperiment (APEX) telescope in April 2021. CONCERTO hosts 2 focal planes and a total number of 4000 Kinetic Inductance Detectors (KID), with an instantaneous FoV of 18.6 arcminutes in the range of 130-310 GHz. The spectral resolution can be easily tuned down to 1 GHz depending on the scientific target. The scientific program of CONCERTO has many objectives, with two main programs focused on mapping the fluctuations of the [CII] line intensity in the reionisation and postreionisation epoch (4.5<z<8.5), and on studying galaxy clusters via the thermal and kinetic Sunyaev-Zel’dovich (SZ) effect. CONCERTO will also measure the dust and molecular gas contents of local and intermediate-redshift galaxies, it will study the Galactic star-forming clouds and finally it will observe the CO intensity fluctuations arising from 0.3<z<2 galaxies.

The design of the instrument, installation at APEX and current status of the commissioning phase and science verification will be presented. Also we describe the deployment and first on-sky tests performed between April and June 2021.

Galactic Star Formation with NIKA2 (GASTON): Evidence of mass accretion onto dense clumps

High-mass stars (m* ≳ 8 M⊙) play a crucial role in the evolution of galaxies, and so it is imperative that we understand how they are formed. We have used the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope to conduct high-sensitivity continuum mapping of ~ 2 deg2 of the Galactic plane (GP) as part of the Galactic Star Formation with NIKA2 (GASTON) large program. We have identified a total of 1467 clumps within our deep 1.15 mm continuum maps and, by using overlapping continuum, molecular line, and maser parallax data, we have determined their distances and physical properties. By placing them upon an approximate evolutionary sequence based upon 8 μm Spitzer imaging, we find evidence that the most massive dense clumps accrete material from their surrounding environment during their early evolution, before dispersing as star formation advances, supporting clump-fed models of high-mass star formation.

Overdensity of SubMillimiter Galaxies in the GJ526 Field mapped with the NIKA2 Camera

Using the NIKA2 dual band millimeter camera installed on the IRAM30m telescope, we have mapped a relatively large field (~ 70 arcmin2) in the direction of the star GJ526 to investigate the nature of the sources found with the MAMBO camera at 1.2 mm ten years earlier. We have found that they must be dust-obscured galaxies (SMGs) in the background beyond the star. The new NIKA2 map at 1.15 mm reveals additional sources and, in fact, an overdensity of SMGs predominantly distributed along a filament-like structure in projection on the sky across the whole observed field. We speculate this might be a cosmic filament at high redshift as revealed in cosmological hydrodynamical simulations. Measurement of spectroscopic redshifts of the SMGs in the candidate filament is required now for a definitive confirmation of the nature of the structure.

Crab nebula at 260 GHz with the NIKA2 polarimeter: Implications for the polarization angle calibration of future CMB experiments

The quest for primordial gravitational waves enclosed in the Cosmic Microwave Background (CMB) polarization B-modes signal motivates the development of a new generation of high sensitive experiments (e.g. CMBS4, LiteBIRD), thus allowing to probe the inflationary epoch in the early Universe. However, this will be only possible by ensuring a high control of the instrumental systematic effects and an accurate absolute calibration of the polarization angle.

The Crab nebula is known to be a polarization calibrator on the sky for CMB experiments. Already used for the Planck satellite it exhibits a high polarized signal at microwave wavelengths. In this work we present Crab polarization observations obtained, in the 260 GHz frequency band, with the NIKA2 instrument. Furthermore, we discuss the accuracy needed on such a measurement to improve the constraints on the absolute angle calibration for CMB experiments.

The LPSZ-CLASH galaxy cluster sample: Combining lensing and hydrostatic mass estimates

Starting from the clusters included in the NIKA sample and in the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ) we have selected a sample of six common objects with the Cluster Lensing And Supernova survey with Hubble (CLASH) lensing data. For the LPSZ clusters we have at our disposal both high-angular resolution observations of the thermal SZ with NIKA and NIKA2 and X-ray observations with XMM-Newton from which hydrostatic mass estimates can be derived. In addition, the CLASH dataset includes lensing convergence maps that can be converted into lensing estimates of the total mass of the cluster. One-dimensional mass profiles are used to derive integrated mass estimates accounting for systematic effects (data processing, modeling, etc.). Two-dimensional analysis of the maps can reveal substructures in the cluster and, therefore, inform us about the dynamical state of each system. Moreover, we are able to study the hydrostatic mass to lensing mass bias, across different morphology and a range of redshift clusters to give more insight on the hydrostatic mass bias. The analysis presented in this proceeding follows the study discussed in [20].

Mapping the intracluster medium temperature in the era of NIKA2 and MUSTANG-2

We present preliminary results from an on-going program that aims at mapping the intracluster medium (ICM) temperature of high redshift galaxy clusters from the MaDCoWS sample using a joint analysis of shallow X-ray data obtained by Chandra and high angular resolution Sunyaev-Zel’dovich (SZ) observations realized with the NIKA2 and MUSTANG-2 cameras. We also present preliminary results from an on-going Open Time program within the NIKA2 collaboration that aims at mapping the ICM temperature of a galaxy cluster at z = 0.45 from the resolved detection of the relativistic corrections to the SZ spectrum. These studies demonstrate how high angular resolution SZ observations will play a major role in the coming decade to push the investigation of ICM dynamics and non-gravitational processes to high redshift before the next generation X-ray observatories come into play.

Dust Emission in Galaxies at Millimeter Wavelengths: Cooling of star forming regions in NGC6946

Interstellar dust plays an important role in the formation of molecular gas and the heating and cooling of the interstellar medium. The spatial distribution of the mm-wavelength dust emission from galaxies is largely unexplored. The NIKA2 Guaranteed Time Project IMEGIN (Interpreting the Millimeter Emission of Galaxies with IRAM and NIKA2) has recently mapped the mm emission in the grand design spiral galaxy NGC6946. By subtracting the contributions from the free-free, synchrotron, and CO line emission, we map the distribution of the pure dust emission at 1:15mm and 2mm. Separating the arm/interarm regions, we find a dominant 2mm emission from interarms indicating the significant role of the general interstellar radiation field in heating the cold dust. Finally, we present maps of the dust mass, temperature, and emissivity index using the Bayesian MCMC modeling of the spectral energy distribution in NGC6946.

GASTON: Galactic Star Formation with NIKA2 A new population of cold massive sources discovered

Understanding where and when the mass of stars is determined is one of the fundamental, mostly unsolved, questions in astronomy. Here, we present the first results of GASTON, the Galactic Star Formation with NIKA2 large programme on the IRAM 30m telescope, that aims to identify new populations of low-brightness sources to tackle the question of stellar mass determination across all masses. In this paper, we focus on the high-mass star formation part of the project, for which we map a ~ 2 deg2 region of the Galactic plane around l = 24° in both 1.2 mm and 2.0 mm continuum. Half-way through the project, we reach a sensitivity of 3.7 mJy/beam at 1.2mm. Even though larger than our target sensitivity of 2 mJy, the current sensitivity already allows the identification of a new population of cold, compact sources that remained undetected in any (sub-)mm Galactic plane survey so far. In fact, about 25% of the ~ 1600 compact sources identified in the 1.2mm GASTON image are new detections. We present a preliminary analysis of the physical properties of the GASTON sources as a function of their evolutionary stage, arguing for a potential evolution of the mass distribution of these sources with time.

KISS: a spectrometric imager for millimetre cosmology

Clusters of galaxies are used to map the large-scale structures in the universe and as probe of universe evolution. They can be observed through the Sunyaev-Zel’dovich (SZ) effect. In this respect the spectro-imaging at low resolution frequency is an important tool, today, for the study of cluster of galaxies. We have developed KISS (KIDs Interferometer Spectrum Survey), a spectrometric imager dedicated to the secondary anisotropies of the Cosmic Microwave Background (CMB). The multi-frequency approach permits to improve the component separation with respect to predecessor experiments. In this paper, firstly, we provide a description of the scientific context and the state of the art of SZ observations. Secondly, we describe the KISS instrument. Finally, we show preliminary results of the ongoing commissioning campaign.

Cluster cosmology with the NIKA2 SZ Large Program

The main limiting factor of cosmological analyses based on thermal Sunyaev-Zel’dovich (SZ) cluster statistics comes from the bias and systematic uncertainties that affect the estimates of the mass of galaxy clusters. High-angular resolution SZ observations at high redshift are needed to study a potential redshift or morphology dependence of both the mean pressure profile and of the mass-observable scaling relation used in SZ cosmological analyses. The NIKA2 camera is a new generation continuum instrument installed at the IRAM 30-m telescope. With a large field of view, a high angular resolution and a high-sensitivity, the NIKA2 camera has unique SZ mapping capabilities. In this paper, we present the NIKA2 SZ large program, aiming at observing a large sample of clusters at redshifts between 0.5 and 0.9, and the characterization of the first cluster oberved with NIKA2.

Mapping the gas thermodynamic properties of the massive cluster merger MOO J1142+1527 at z = 1.2

We present the results of the analysis of the very massive cluster MOO J1142+1527 at a redshift z = 1.2 based on high angular resolution NIKA2 Sunyaev-Zel’dovich (SZ) andChandraX-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 andChandramaps together with the analysis of the entropy map allows us to conclude that MOOJ1142+1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties atz>1.

Observing with NIKA2Pol from the IRAM 30m telescope : Early results on the commissioning phase

The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarime-ter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separates the two orthogonal polarizations onto two 260 GHz KIDs arrays. We describe in this paper the preliminary results obtained during the most recent commissioning campaign performed in December 2018. We concentrate here on the analysis of the extended sources, while the observation of compact sources is presented in a companion paper [12]. We present preliminary NIKA2 polarization maps of the Crab nebula. We find that the integrated polarization intensity flux measured by NIKA2 is consistent with expectations. In terms of polarization angle, we are still limited by systematic uncertainties that will be further investigated in the forthcoming commissioning campaigns.

Preliminary results on the instrumental polarization of NIKA2-Pol at the IRAM 30m telescope

Clarifying the role of magnetic fields in the star formation process is crucial. Observations have already shown that magnetic fields play an important role in the early stages of star formation. The high spatial resolution (∼0.01 to 0.05 pc) provided by NIKA2-Pol 1.2 mm imaging polarimetry of nearby clouds will help us clarify the geometry of the B-field within dense cores and molecular filaments as part of the IRAM 30m large program B-FUN. There are numerous challenging issues in the validation of NIKA2-Pol such as the calibration of instrumental polarization. The commissioning phase of NIKA2-Pol is underway and is helping us characterize the intensity-to-polarization “leakage” pattern of the instrument. We present a preliminary analysis of the leakage pattern and its dependence with elevation. We also present the current leakage correction made possible by the NIKA2 pipeline in polarization mode based on the NIKA2-Pol commissioning data taken in December 2018. Based on reduced Stokes I, Q, U data we find that the leakage pattern of NIKA2-Pol depends on elevation and is sensitive to the focus of the telescope.

Debris disks around stars in the NIKA2 era

The new NIKA2 camera at the IRAM 30m radiotelescope was used to observe three known debris disks in order to constrain the SED of their dust emission in the millimeter wavelength domain. We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the Rayleigh-Jeans regime (λ-2), unlike the steeper spectra (λ-3) measured in the submillimeter-wavelength domain for two of the three disks - around the stars Vega and HD107146. We provide a succesful proof of concept to model this spectral inversion in using two populations of dust grains, those smaller and those larger than a grain radius a0 of 0.5mm. This is obtained in breaking the slope of the size distribution and the functional form of the absorption coefficient of the standard model. The third disk - around the star HR8799 - does not exhibit this spectral inversion but is also the youngest.

NIKA2 mapping and cross-instrument SED extraction of extended sources with Scanamorphos

The steps taken to tailor to NIKA2 observations the Scanamorphos algorithm (initially developed to subtract low-frequency noise from Herschel on-the-fly observations) are described, focussing on the consequences of the different instrument architecture and observation strategy. The method, making the most extensive use of the redundancy built in the multi-scan coverage with large arrays of a given region of the sky, is applicable to extended sources, while the pipeline is so far optimized for compact sources. An example of application is given. A related tool to build consistent broadband SEDs from 60 microns to 2 mm, combining Herschel and NIKA2 data, has also been developed. Its main task is to process the data least affected by low-frequency noise and coverage limitations (i.e. the Herschel data) through the same transfer function as the NIKA2 data, simulating the same scan geometry and applying the same noise and atmospheric signal as extracted from the 1mm and 2mm data.

The NIKA polarimeter on science targets: Crab nebula observations at 150 GHz and dual-band polarization images of Orion Molecular Cloud OMC-1

We present here the polarization system of the NIKA camera and give a summary of the main results obtained and performed studies on Orion and the Crab nebula. The polarization system was equipped with a room temperature continuously rotating multi-mesh half wave plate and a grid polarizer facing the NIKA cryostat window. NIKA even though less sensitive than NIKA2 had polarization capability in both 1 and 2 millimiter bands. NIKA polarization observations demonstrated the ability of such a technology in detecting the polarization of different targets, compact and extended sources like the Crab nebula and Orion Molecular Cloud region OMC-1. These measurements together with the developed techniques to deal with systematics, opened the way to the current observations of NIKA2 in polarization that will provide important advances in the studies of galactic and extra-galactic emission and magnetic fields.

NIKA: a mm camera for Sunyaev-Zel’dovich science in clusters of galaxies

Clusters of galaxies, the largest bound objects in the Universe, constitute a cosmological probe of choice, which is sensitive to both dark matter and dark energy. Within this framework, the Sunyaev-Zel’dovich (SZ) effect has opened a new window for the detection of clusters of galaxies and for the characterization of their physical properties such as mass, pressure and temperature. NIKA, a KID-based dual band camera installed at the IRAM 30-m telescope, was particularly well adapted in terms of frequency, angular resolution, field-of-view and sensitivity, for the mapping of the thermal and kinetic SZ effect in high-redshift clusters. In this paper, we present the NIKA cluster sample and a review of the main results obtained via the measurement of the SZ effect on those clusters: reconstruction of the cluster radial pressure profile, mass, temperature and velocity.

A low-mass galaxy cluster as a test-case study for the NIKA2 SZ Large Program

High-resolution mapping of the hot gas in galaxy clusters is a key tool for cluster-based cosmological analyses. Taking advantage of the NIKA2 millimeter camera operated at the IRAM 30-m telescope, the NIKA2 SZ Large Program seeks to get a high-resolution follow-up of 45 galaxy clusters covering a wide mass range at high redshift in order to re-calibrate some of the tools needed for the cosmological exploitation of SZ surveys. We present the second cluster analysis of this program, targeting one of the faintest sources of the sample in order to tackle the difficulties in data reduction for such faint, low-SNR clusters. In this study, the main challenge is the precise estimation of the contamination by sub-millimetric point sources, which greatly affects the tSZ map of the cluster. We account for this contamination by performing a joint fit of the SZ signal and of the flux density of the compact sources. A prior knowledge of these fluxes is given by the adjustment of the SED of each source using data from both NIKA2 and the Herschel satellite. The first results are very promising and demonstrate the possibility to estimate thermodynamic properties with NIKA2, even in a compact cluster heavily contaminated by point sources.

Gastric paraganglioma: case report and review of the literature

Very few cases of gastric paragangliomas have been reported in the literature to date. We report a rare case of parietal gastric paraganglioma fortuitously detected during intraoperative exploration. A 82-years-old woman presented to our emergency room for abdominal pain. On physical examination abdomen was painful on palpation and Blumberg's sign was present. The laboratory exams showed a neutrophilia in absence of leukocytosis. Acute appendicitis was suspected and a laparoscopy was performed. At exploration, the vermiform appendix was normal while a lumpy, hard-fibrous and white-pinkish extraluminal lesion of the anterior wall of the gastric body near the greater curvature of about 2 cm in diameter was present. Laparoscopic resection of the gastric lesion was performed. The patient was discharged in good condition in the fourth postoperative day. Pathologic examination revealed a gangliocitic paraganglioma. The patient is alive and well without evidence of relapse 6 months after surgery. Gastric paraganglioma is a very rare tumor and its diagnosis is very difficult. Surgical excision is the treatment of choice which can be performed successfully with laparoscopy.

Does antithrombotic prophylaxis worsen early outcomes of total thyroidectomy? - a retrospective cohort study

Background

Currently, there is no strong evidence on the effectiveness and safety of pharmacological antithrombotic prophylaxis in thyroid surgery. The aim of this study was to establish whether the prophylactic use of low-molecular-weight heparin (LMWH) could negatively affect the early outcomes of patients undergoing total thyroidectomy.

Methods

Data from patients submitted to total thyroidectomy between February 2013 and October 2017 were retrospectively collected and analysed. Only patients with indication to antithrombotic prophylaxis according to current guidelines were included in the study. Eligible cases were divided into two groups, which corresponded to two distinct periods of our surgical practice: Group A, which included 178 consecutive patients who were submitted to antithrombotic prophylaxis with LMWH, and Group B, which included 348 consecutive patients who did not receive prophylaxis. Primary endpoints were the incidence of post-operative cervical haematomas (POCH) and thromboembolic events. Secondary endpoint was the length of postoperative hospital stay. Statistical analysis was performed by using Student’s t test for continuous variables and Chi-square test for categorical variables. A P value of less than 0.05 was considered statistically significant.

Results

The two groups of patients were comparable in terms of age, gender, thyroid disease, duration of surgery, and weight of the thyroid gland. Overall, no thromboembolic events were registered. The comparative analysis of the other outcome measures, showed no significant differences between the two groups (POCH: 2 cases (1.12%) in Group A vs 8 cases (2.30%) in Group B - p 0.349; Postoperative hospital stay: 2.90 ± 0.86 days in Group A vs 2.89 ± 0.99 days in Group B - p 0.908).

Conclusions

Data from this study do not support or contraindicate the use of antithrombotic prophylaxis in thyroid surgery. However, since thyroidectomy is a closed-space procedure, and even modest bleeding may quickly result in airway compression and death by asphyxia, mechanical prophylaxis should be preferred to LMWH whenever possible.

Trial registration

ISRCTN ISRCTN12029395. Registered 05/02/2018 retrospectively registered.

Peripheral Blood Lymphocyte Response to Exogenous Interleukin 2 by PHA-Prestimulated and Non-PHA-Prestimulated Cells in Patients with Cancer

The study aims were 1) to assess the response of peripheral blood lymphocytes (PBL) of cancer patients to exogenous Interleukin 2 (IL 2) either by PHA-prestimulated or non PHA-prestimulated PBL, and 2) to carry out preliminary experiments for a direct quantitative evaluation of endogenous IL 2 production by PBL cultures of cancer patients in order to define the actual role of IL 2 in the disease. Analysis of PBL subsets was also carried out with monoclonal antibodies in a selected group of patients. A total of 134 patients entered the study. Cancer sites were: larynx 32, breast 36, lung (NSC) 24, colorectal 17 and gynecologic 25. In the former 3 cancer sites staging showed localized or only locally advanced disease, and in the last 2 sites disseminated disease. Our results provided evidence that cancer patients exhibit a T-cell functional immunodepression, which progresses during tumor growth, so that the localized disease shows a low-grade defect, and advanced disease a high-grade defect. Our data also clearly suggested that the factor involved with a primary role in this functional immune impairment is the IL 2 deficiency. A perspective may be drawn on the therapeutic administration in vivo of IL 2 and IL 2-activated lymphokine-activated killer cells in controlled clinical trials of selected groups of cancer patients.

Surgical management of gynecomastia: experience of a general surgery center

AIM

Gynecomastia is a common finding in male population of all ages. The aim of our study was to present our experience and goals in surgical treatment of gynecomastia.

PATIENTS AND METHODS

Clinical records of patients affected by gynecomastia referred to our Department of Surgery between September 2008 and January 2015 were analyzed. 50 patients were included in this study.

RESULTS

Gynecomastia was monolateral in 12 patients (24%) and bilateral in 38 (76%); idiopathic in 41 patients (82%) and secondary in 9 (18%). 39 patients (78%) underwent surgical operation under general anaesthesia, 11 (22%) under local anaesthesia. 3 patients (6%) presented recurrent disease. Webster technique was performed in 28 patients (56%), Davidson technique in 16 patients (32%); in 2 patients (4%) Pitanguy technique was performed and in 4 patients (8%) a mixed surgical technique was performed. Mean surgical time was 80.72±35.14 minutes, median postoperative stay was 1.46±0.88 days. 2 patients (4%) operated using Davidson technique developed a hematoma, 1 patient (2%) operated with the same technique developed hypertrophic scar.

CONCLUSIONS

Several surgical techniques are described for surgical correction of gynecomastia. If performed by skilled general surgeons surgical treatment of gynecomastia is safe and permits to reach satisfactory aesthetic results.

Differentiated thyroid cancer: feasibility of loboisthmectomy in an endemic region

AIM

The aim of the present retrospective study was to assess the feasibility of loboisthmectomy for the treatment of differentiated thyroid cancer in a endemic area, evaluating the histopathological features and the results of a case series of 1154 patients.

PATIENTS AND METHODS

The clinical records of 1154 patients submitted to total thyroidectomy in our Department were retrospectively reviewed to analyze the histopathological characters and the results.

RESULTS

In 1044 cases (90.5%) a papillary cancer was observed, in 110 (9.5%) a follicular carcinoma; microcarcinomas were 399 (34.5%). Multifocality was present in 323 cases (28%), in 142 unilateral (12.3%) and in 181 bilateral (15.7%). Thyroiditis coexisted in 472 patients (40.9%), multinodular goiter in 404 (35%), Graves' disease in 48 (4.1%), and multinodular toxic goiter in 38 (3.3%). Complications were: postoperative bleeding in 20 patients (1.7%), transient unilateral vocal cord paralysis in 20 (1.7%) definitive in 10 (0.86%), a transient bilateral paralysis in 1 (0.08%), a transient hypoparathyroidism in 351 (30.4%), and a definitive in 24 (2.07%). Nodal recurrence occurred in 25 patients (2.16%).

CONCLUSIONS

Total thyroidectomy remains the safest treatment in differentiated thyroid cancer, especially if performed in high volume centers in which complications can be minimized. Loboisthmectomy can be a viable and safe alternative in small (< 1 cm) unifocal tumors in patients at low risk. Loboisthmectomy is limited in endemic areas by the association with other thyroid diseases. A correct and detailed information of the patient is essential before planning surgery.

Subclinical atherosclerosis is associated with Epicardial Fat Thickness and hepatic steatosis in the general population

BACKGROUND AND AIMS

Abdominal obesity and hepatic steatosis are ectopic fat depots associated with Metabolic Syndrome (MetS). Epicardial Fat Thickness (EFT) is a newly discovered one, increasing with obesity, insulin resistance and MetS. Therefore we studied whether different ectopic fat markers, and EFT in particular, are associated with MetS and markers of subclinical cardiovascular disease.

METHODS AND RESULTS

868 subjects from the PLIC Study were included, EFT, aortic calcifications, carotid Intima-Media Thickness (c-IMT) and echocardiographic parameters were determined by ultrasound; extra-cardiac atherosclerotic lesions were defined in presence of plaques at both carotid and aortic levels. Hepatic steatosis degrees were defined according to a scoring system. Abdominal adiposity was determined using Dual X-ray Absorbimetry (DEXA). Independently from age, women showed higher EFT versus men (4.5 (0.20-9.00) mm vs 4.00 (0.10-8.00) mm, p = 0.013); EFT was thicker in post-menopausal women (independently from hormone-replacement therapy). EFT, liver steatosis and abdominal adiposity increased with MetS (p < 0.001). EFT was the only ectopic fat marker associated with cardiac dysfunction (OR = 1.340 [1.088-1.651 95% C.I., p = 0.006); liver steatosis and EFT were associated with extra-cardiac plaques (OR = 2.529 [1.328-4.819] 95% C.I., p < 0.001 and OR = 1.195 [1.008-1.299] 95% C.I., p = 0.042; respectively). On top of cardiovascular risk factors, only EFT improved the discrimination of subjects with cardiac dysfunction and atherosclerotic plaques.

CONCLUSIONS

EFT is associated with left ventricular dysfunction and subclinical atherosclerosis. Our data suggest that EFT may represent an additional tool for the stratification of cardiovascular risk.

Difficulties in the diagnosis of thyroid paraganglioma: a clinical case

Thyroid Paragangliomas are exceptionally rare tumors and only 35 documented cases have been reported in the literature. We report an additional unusual male case of thyroid Paraganglioma associated to a chronic lymphocytic thyroiditis and a papillary microcarcinoma. A 45-year-old man presented with a solitary thyroid nodule. Physical examination revealed a smooth, well-circumscribed, firm, mobile, painless thyroid nodule in the right lobe measuring 3 cm. Ultrasound examination showed a 40 mm hypoechoic, non-homogeneous nodule with peri- and intra-nodular vascular flow. An ultrasound-guided fine needle aspiration biopsy was performed showing the presence of atypical cells (Thy 3). He underwent a total thyroidectomy associated to VI level lymphectomy. Histology showed a thyroid Paraganglioma associated to a chronic lymphocytic thyroiditis and a papillary microcarcinoma measuring 0.3 cm in the greatest dimension. Thyroid Paraganglioma is an elusive tumor. It is difficult to diagnose and should be included in the differential diagnosis of all neuroendocrine tumors of the thyroid, even those arising in men or behaving in a locally aggressive fashion.

Intraoperative recurrent laryngeal nerve monitoring in thyroid surgery: is it really useful?

AIM

The aim of this study was to evaluate the ability of intraoperative recurrent laryngeal nerve monitoring to predict the postoperative functional outcome and the potential role of this technique in reducing the postoperative nerve palsy rate.

MATERIALS AND METHODS

Between June 2007 and December 2011, 1693 consecutive patients who underwent thyroidectomy by a single surgical team were evaluated. We compared patients who have had a neuromonitoring and patients who have undergone surgery with the only visualization. Patients in which NIM was not utilized (Group A) were 942 against the others 751 (group B).

RESULTS

In group A there were 28 recurrent laryngeal nerve injuries (2.97%) of which 21 were transients (2.22%) and 7 were permanents (0.74%). In group B there were 20 recurrent laryngeal nerve injuries (2.66%) of which 14 (1.86%) transients and 6 (0.8%) permanents. Differences between the two groups were not statistically significative.

CONCLUSIONS

The technique of intraoperative neuromonitoring in thyroid surgery is safe and reliable in excluding postoperative recurrent laryngeal nerve palsy; it has high accuracy, specificity, sensitivity and negative predictive value. Neuromonitoring is useful to identify the recurrent laryngeal nerve and it can be a useful adjunctive technique for reassuring surgeons of the functional integrity of the nerve but it does not decrease the incidence of injuries compared with visualization alone. Its application can be particularly recommended for high-risk thyroidectomies.

Relationship between apathy and cognitive dysfunctions in de novo untreated Parkinson's disease: a prospective longitudinal study

BACKGROUND AND PURPOSE

Apathy may be either a symptom of major depression or a behavioral disturbance occurring in concomitance with depression or alone in Parkinson's disease (PD). The aim of the present study was to determine the progression of cognitive impairment in drug-naïve untreated PD patients with or without clinically significant apathy.

METHODS

Sixty-two PD patients with a disease duration <2 years and without history of present or past therapy with pro-dopaminergic agents were included and underwent the Apathy Evaluation Scale (S-AES), a clinical interview based on diagnostic criteria for apathy and a comprehensive neuropsychological battery to assess memory, frontal functions and visuospatial functions. Two years after the first assessment, all patients were re-evaluated on the S-AES, a clinical interview and neuropsychological tests.

RESULTS

According to the cut-off value of the S-AES and diagnostic criteria for apathy, eight patients experienced apathy at both baseline and follow-up (A+A+), nine patients had apathy only at follow-up (A-A+), 37 patients never experienced apathy (A-A-) and eight patients showed apathy at the baseline only (A+A-). Cognitive performance significantly declined in all four groups. At both baseline and follow-up A+A+ performed worse than A-A- on visuospatial and frontal tests; A-A+ had lower scores than A-A- on the interference task of the Stroop test (IT-ST). Regression analysis showed that poor performance on the IT-ST at baseline was the only independent predictor of onset of apathy at follow-up.

CONCLUSIONS

The results indicated a relationship between apathy and dysexecutive syndrome in early PD. Reduced scores on the IT-ST may predict development of apathy in PD patients.

Risk factors in reoperative thyroid surgery for recurrent goitre: our experience

AIM

Reoperative thyroid surgery is an uncommon operation associated with a higher complication rate; we reviewed our series of patients on whom reoperative thyroid surgery was performed.

METHOD

106 patients had a thyroid reoperation for recurrent multinodular goiter (93 patients), recurrent thyrotoxicosis (3) or suspected malignancy (10); bilateral completion thyroidectomy was performed in 68 cases, lobectomy in 36, removal of a mediastinal recurrence and of a pyramidal remnant in 1 patient respectively.

RESULTS

Temporary hypoparathyroidism occurred in 41 patients (38.67%), definitive in 7 (6.6%), transient recurrent laryngeal nerve palsy in 5 (4.71%), permanent nerve palsy in 1 (0.94%); in 3 cases (2.83%) surgical revision of haemostasis was necessary for postoperative haemorrhage. After monolateral surgery we had 13 cases of transient hypoparathyroidism (34.21%), 2 of definitive (5.26%) and 1 transient recurrent laryngeal nerve palsy (2.63%); after bilateral surgery we had 29 cases of transient hypoparathyroidism (42.64%), 5 of definitive (7.35%), 4 of transient recurrent laryngeal nerve palsy (5.88%), 1 of definitive (1.47%) and 3 of postoperative bleeding (4.41%).

CONCLUSIONS

Reoperative thyroid surgery is a technical challenge with a high incidence of complications. Scarring, edema and friability of the tissues together with distortion of the landmarks make reoperative surgery hazardous. A higher risk of complications is described when previous surgery has been performed on both sides. Total thyroidectomy should be considered the procedure of choice for benign multinodular goiter eliminating the potential of a reoperation. Whenever necessary, reoperative thyroidectomy may be performed safely with little morbidity in experienced hands.

Intraoperative parathyroid hormone assay during focused parathyroidectomy for primary hyperparathyroidism: is it really mandatory?

AIM

Intraoperative parathyroid hormone (PTH) assay has become an essential tool in focused parathyroid surgery. The aim of this study was to evaluate the present role of intraoperative PTH monitoring during focused parathyroidectomy for primary hyperparathyroidism in our experience.

METHODS

One hundred sixty-one patients were submitted to focused parathyroidectomy with rapid intraoperative Parathyroid hormone assay monitoring.

RESULTS

A >50% decrease of PTH occurred in 147 patients (91.3%); in this group persistent hypercalcemia was found in 1; in the remaining 14 (8.7%) values of PTH decreased less than 50% and bilateral neck exploration was performed. An additional pathologic parathyroid was removed in 8 cases, a third in one; in the other five further neck exploration was negative and in four of these persistent postoperative hypercalcemia was demonstrated. In 136 patients >50% decrease of PTH was obtained after 10 minutes, in the other 11 after 20. The overall operative success of the patients was 96.9% with a 5.6% incidence of multiglandular disease. Intraoperative parathormone monitoring changed the operative management in 8.7% of cases. Intraoperative parathormone monitoring was accurate in predicting operative success or failure in 98.7% of patients, with a sensitivity of 99.3%, a specificity of 92.8%, a positive predictive value of 99.3% and a negative predictive value of 92.8%.

DISCUSSION AND CONCLUSION

The measurement of intraoperative PTH represents a useful tool to assist the surgeon during parathyroid surgery and its routine use significantly improves cure rates of focused parathyroidectomy. We believe that the use intraoperative PTH is still mandatory in focused parathyroidectomy avoiding relapses and consequent reintervention.

Isolated inguinal endometriosis. Case report with ultrasonographic preoperative diagnosis

Inguinal endometriosis is rare and accounts for 0.3-0.6% of patients affected by endometriosis. A correct preoperative diagnosis is rare. Diagnosis is frequently made by histologic examination. A 36-year-old nulliparous woman presented with a painful mass in her right groin of 2 years duration. The pain fluctuated according to the menstrual period. Physical examination revealed an elastic hard mobile mass measuring 2 x 2 cm in the right inguinal region. Ultrasound examination confirmed a hypoechoic tumor in the right inguinal region with poorly defined boundaries and perilesional and intralesional vascular flow suspect for endometriosis. Wide excision of the lump with a part of the round ligament was carried out. Histology showed endometrial glands and stroma within the fibrous tissue. The patient had an uneventful recovery and was discharged the next day. After surgery, the pain disappeared completely. No signs of recurrence occurred at approximately 16 months after the surgery. Although rare, extrapelvic endometriosis should be considered in the differential diagnosis in women of reproductive age presenting with an inguinal mass, especially if the groin mass is associated in size and tenderness with menstrual variability. US appearance is very useful in diagnosis so ultrasonography can be considered the examination of choice.

[New techniques in parathyroid surgery]

The diseases of parathyroid glands have assumed a growing importance for innovations in diagnosis and surgery which have enabled a more precise identification and therapy. Use of Sesta-MIBI scintigraphy allows a correct localization of the adenoma; the introduction of intraoperative monitoring of intact parathyroid hormone made possible unilateral neck exploration with a mini-incision above the adenoma. The emergence of videotechnology has led the innovation of endoscopic parathyroidectomy, realized for the first time in 1996 and subsequently performed without the use of CO2. Currently, the SPECT scintigraphy allows a three-dimensional vision of the adenoma and is the more precise localization study, allowing to use mini-invasive access. Prerequisite for the use of minimally invasive techniques is the determination of intraoperative PTH, possible with various techniques. Our experience is based on 135 patients undergoing parathyroidectomy in the last 8 years with 5 cases of persistent hyperparathyroidism submitted to reoperation, an average hospital stay of 2 days and only 6 complications (1 bleeding and 5 temporary hypoparathyroidisms). The use of new technologies in parathyroid surgery can achieve optimal results, a better cosmetic result and quicker postoperative recovery, with a low incidence of recurrence and complications.

ACE and LRPAP1 insertion-deletion polymorphisms in a northern Ivory Coast population

The ACE and the LRPAP1 gene insertion-deletion polymorphisms were determined in 133 healthy individuals sampled from Ouangolodougou, a village located in northern Ivory Coast. No sex differences were found in ACE and LRPAP1 gene frequencies. The ACE insertion and deletion alleles had frequencies of 0.346 and 0.654, respectively. The ACE gene was not in Hardy-Weinberg equilibrium because of an excess of heterozygote genotypes and a deficiency of I/I genotypes compared to the expected values. Statistical analysis showed a significantly lower frequency of I/I genotypes in the Ivory Coast population compared to Sudan, Kenya, African Americans, and African Brazilians (p < 0.05), whereas no differences were found with respect to Somalia. Conversely, the frequencies of the insertion and deletion alleles in the Ivorian population did not differ from those of other African populations. The LRPAP1 insertion and deletion allele frequencies found in our study (0.192 and 0.808, respectively) did not differ significantly from the Czech and Spanish populations, the only two populations previously characterized for this polymorphism. However, the frequency of the I/I genotype was significantly lower than the frequencies observed in the European samples. Because of the limited information on the LRPAP1 gene polymorphism distribution in worldwide populations, it was not possible to draw any conclusion.

Endometriosis of the round ligament: description of a clinical case and review of the literature

We report a case of endometriosis of the round ligament in a 29-year-old woman, who complained of a lump with a diameter of about 2.5 cm in the right inguinal region, which increased in bulk and was accompanied by intense pain during the menstrual period. The clinical suspicion of inguinal endometriosis, supported by ultrasonography and Magnetic Resonance (MR), was confirmed by histological examination of the surgical specimen, which included the mass and the extraperitoneal segment of the round ligament. The authors conclude that the appearance of a lump in the inguinal region associated with subjective and objective changes of the lesion in relation to the menstrual cycle must raise the suspicion of endometriosis among the possible diagnoses.

Operative cholangiography during laparoscopic cholecystectomy: considerations about routine or selective policy

Operative cholangiography (OC) during laparoscopic cholecystectomy (LC) is still a matter of debate regarding its routine or selective use. The present report is based upon a series of 30 selective cholangiographies performed in 290 LC during the years 1999-2004. Indications to OC were decided according to clinical data, liver chemistries, ultrasonographic (US) and intraoperative findings. In cases of unequivocal common bile duct (CBD) stones, a preoperative ERCP was performed and OC was not applied to confirm clearing of the biliary tract. OC was successful in 26 cases (86.6%): in 18 cases a normal cholangiogram was obtained and in 3 cases stones were detected into CBD. These patients underwent a postoperative successful ERCP at a variable interval of time. In 4 cases cholangiograms showed a delayed transit and in a single case a lack of contrast into the duodenum. Such occurrence was due to morphine derivatives employed during anesthesia. The Authors evaluate advantages and drawbacks of routine and selective OC according to personal and other Authors experience. Decision on selective or routine policy should be taken according to each surgeon experience and local facilities. Each laparoscopic surgeon must be able to perform and interpret an OC, specially if he has in mind to develop competence in laparoscopic CBD exploration.

Radical treatment of acute pilonidal abscess by marsupialization

Simple drainage is the most common treatment of pilonidal abscess, but later definitive surgery is often necessary. However, radical treatment can also be performed in a single step by several procedures and even better results. The Authors describe the technique of marsupialization and analyse its long-term outcomes in a retrospective study. Between 1992 and 2001, 43 consecutive patients underwent drainage, curettage and marsupialization for acute pilonidal abscess. The procedure was carried out in outpatient setting (day surgery) after local or spinal anaesthesia. Management of the wound was left to the patient and was periodically checked at our out service. The average operating time was 20 minutes. Complete healing required 4-10 weeks in 95.3% of the patients; a persistent chronic fistula was observed in 4.7%. During the follow-up, 6 recurrences (14.6%) were observed in the healed patients. The treatment was then successful in 81.3% of the cases. Our experience shows that it is possible to carry out a radical management of pilonidal abscess in a single step with a high complete healing rate. Marsupialization proved to be a fast procedure and mainly feasible in the outpatient setting.