Hypodermis involvement in skin disorders: Imaging and functional imaging diagnostic tools

The human dermal white adipose tissue (dWAT) morphology: A multimodal imaging approach

BACKGROUND

Dermal white adipose tissue (dWAT) in humans can be characterized as a relaxed dermal skin compartment consisting of functionally interlinked adipocytes. dWAT is typically discerned both in terms of morphology and function from subcutaneous white adipose tissue (sWAT). In particular in human thigh, the dWAT appears as thin extensions from the adipose panniculus to the dermis, and it is primarily associated with pilosebaceous units, hair follicles, sebaceous glands, and erector pili muscles. In this work, human fat tissue samples obtained post-mortem from the gluteo-femoral region were analyzed focusing on the thin extensions of dWAT named dermal cones. This anatomical region was chosen to deepen the dWAT morphological features of this site which is interesting both for clinical applications and genetical studies. The purpose of this exploratory methodological study was to gain deeper insights into the morphological features of human dWAT through a multimodal imaging approach.

METHODS

Optical microscopy, Magnetic Resonance Imaging (MRI) and Scanning Electron Microscopy (SEM), have been employed in this study. The cones' length and their distances were measured on the acquired images for optical microscopy and SEM. The cone's apparent regular distribution in MRI images was evaluated using a mathematical criterion, the conformity ratio, which is the ratio of the mean nearest-neighbor distance to its standard deviation.

RESULTS

The imaging techniques revealed white adipocytes forming a layer, referred to as sWAT, with cones measuring nearly 2 mm in size measured on SEM and Optical images (2.1 ± 0.4 mm), with the lower part embedded in the sWAT and the upper part extending into the dermis. The distance between the cones results about 1 mm measured on MRI images and they show an overall semiregular distribution.

CONCLUSIONS

MRI images demonstrated an orderly arrangement of cones, and their 3D reconstruction allowed to elucidate the dermal cones' disposition in the tissue sample and a more general comprehensive visualization of the entire fat structure within the dermis.

Stretch marks: a visible expression of connective's involvement in autism spectrum disorders

In autism spectrum disorders (ASDs) in the pediatric population, skin manifestations are generally attributable to the concomitance of allergic forms or to accidental, self-inflicted or abusive lesions. However, clinical evidence has highlighted the presence of an increasing number of abdominal stretch marks, probably caused by the increase in the number of obesity cases in the pediatric population, in general, and therefore also among children with ASD. Stretch marks are often attributed to obesity, as they have an incidence of more than 50% in obese individuals. In the first part of this article we hypothesized that in addition to obesity there are other factors, such as a structural alteration on the skin in people with ASD, which can contribute/aggravate the phenomenon of stretch marks. Despite the high frequency with which stretch marks are found in children with ASD, this aspect has never been studied, the structure of the skin of children with ASD is not known. Furthermore, it is not known whether this structure is different from that of subjects without ASD. In the second part of the article, we hypothesized the mechanisms of the negative impact of simple abdominal stretch marks on the symptomatic picture of children with ASD. The presence of stretch marks, altered tactile perception, altered sensitivity to clothing fabrics can be a combination that influences development and determines negative consequences in the neurological picture of a child with ASD, as it is already known that the altered sensory perception in children with ASD contributes to the deterioration of social behavior. Furthermore, the presence of stretch marks may play a role in the postural and motor defects of children with ASD.