‘Hints’ in the horn: diagnostic clues in the stratum corneum

The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process.     

A dual concept of nevogenesis:Theoretical considerations based on dermoscopic features of melanocytic nevi

The dermoscopic features of melanocytic nevi in children are clearly different from those in adults. While nevi in children show almost exclusively globular patterns, those in adults usually exhibit reticular patterns. These remarkable differences could be explained by a dual concept of nevogenesis, based on current clinico‐epidemiologic, dermoscopic, histopathologic and genetic data.     

Proficiency testing for psychoactive substances in Italy

This paper describes the general design and main results of the Italian proficiency testing program for the analysis of psychoactive substances in urine, a long-term initiative created in 1995 on an educational basis and characterized by an innovative internet-based service for data exchange between laboratories and the organizing body. Batches of six urine samples, validated by reference laboratories, are sent every 3 months to participating laboratories, which may choose which classes of substances to test from those planned by the program panel and, within those classes, which type of analytical commitment to work on: identification of just one class (Option 1), identification of single substances (Option 2), or identification and quantification of single substances (Option 3). Comprehensive periodical reports and annual reports are provided to participants with evaluation of their performance and an annual workshop is organized to discuss technical-scientific topics related to clinical, forensic and analytical toxicology. About 200 laboratories currently participate in the program and a total of 67,059 analyses have been carried out since 1995. The mean percentage of correct results was 96.8%, with a yearly improvement of about 0.4%. The best average false positive and false negative rates were obtained for methadone (0.2% and 2.1% respectively) and cocaine (0.3% and 2.2%). The worst average false positive rates were obtained for amphetamines and opiates (3.2% and 5.0%) and worst average false negative rates for amphetamines, barbiturates and cannabinoids (17.4%, 30.7% and 19.9%). Received: 29 June 1998 / Received in revised form: 23 February 1999     

The pattern of lymph node metastases in microsatellite unstable gastric cancer

Background

Microsatellite instability (MSI) is one of the new groups of molecular divisions of gastric cancer (GC). The aim of this study was to investigate the pattern of lymph node metastasis according to MSI status.

Intracortical inhibition and facilitation upon awakening from different sleep stages: a transcranial magnetic stimulation study

Intracortical facilitation and inhibition, as assessed by the paired-pulse transcranial magnetic stimulation technique with a subthreshold conditioning pulse followed by a suprathreshold test pulse, was studied upon awakening from REM and slow-wave sleep (SWS). Ten normal subjects were studied for four consecutive nights. Intracortical facilitation and inhibition were assessed upon awakening from SWS and REM sleep, and during a presleep baseline. Independently of sleep stage at awakening, intracortical inhibition was found at 1-3-ms interstimulus intervals and facilitation at 7-15-ms interstimulus intervals. Motor thresholds were higher in SWS awakenings, with no differences between REM awakenings and wakefulness, while motor evoked potential amplitude to unconditioned stimuli decreased upon REM awakening as compared to the other conditions. REM sleep awakenings showed a significant increase of intracortical facilitation at 10 and 15 ms, while intracortical inhibition was not affected by sleep stage at awakening. While the dissociation between motor thresholds and motor evoked potential amplitudes could be explained by the different excitability of the corticospinal system during SWS and REM sleep, the heightened cortical facilitation upon awakening from REM sleep points to a cortical motor activation during this stage.