Comparison of Histological Skin Changes After Massive Weight Loss in Post-bariatric and Non-bariatric Patients

Abstract

Background: Changes in the skin structure, including the collagen and elastin content, have been reported with massive weight loss (MWL) following bariatric metabolic surgery (BMS) and have been correlated to a higher risk of complications after body-contouring surgery (BCS). This study aimed at comparing the histological characteristics of the skin of patients having surgical MWL (SMWL) post-BMS to those with non-surgical massive weight loss (NSMWL).

Methods: This prospective study compared the epidermal thickness, and collagen and elastin fibers content in 80 skin biopsies obtained from BCS procedures performed to patients who experienced MWL defined more than 50% of excess weight loss (%EWL) either SMWL (40 biopsies) or NSMWL (40 biopsies). Twenty biopsies in each group were obtained from abdominoplasties and 20 from breast reductions. Epidermal thickness was measured in H&E-stained sections, collagen fibers were assessed using Masson trichrome-stained sections, and elastin fibers were assessed using Modified Verhoeff's stained sections. Image analysis software was used to calculate the fractions of collagen and elastin fibers.

Results: This study included 77 patients, 38 SMWL patients, and 39 NSMWL patients. The SMWL group had a significantly higher age (p < 0.001), a longer time interval from intervention (p < 0.001), higher initial weight (p < 0.001), higher initial BMI (p < 0.001), lower current weight (p = 0.005), lower current BMI (p < 0.001), and significantly higher %EWL than NSMWL group (p < 0.001). No significant differences were detected between the two groups regarding complications after abdominoplasty (p = 1.000). The elastic fibers content in the dermis was significantly higher in the abdominal region of the NSMWL group than SMWL (p = 0.029). All other parameters showed non-significant differences between NSMWL and SMWL in the skin of abdomen and breast.

Conclusion: The SMWL group had a significant reduction in elastic fiber content in the skin of the abdomen compared to the NSMWL group. The collagen content was equally reduced in both groups with non-significant differences in both breast and abdomen regions in both groups.

Keywords: Bariatric metabolic surgery; Body-contouring surgery; Collagen; Elastin; Epidermal thickness; Massive weight loss; Non-surgical weight loss; Skin changes; Skin histology.

Fig. 1

Assessment of different histopathologic skin parameters in this study at × 200 power (scale bar = 100 microns): A H&E-stained section to measure the epidermal thickness (black line). B Masson trichrome-stained section to assess collagen bundles which stained blue. The photo is changed into gray scale image (upper photo); then, segmentation of color was done to assess percentage of collagen fibers (lower photo) C Modified Verhoeff’s stained section to assess the elastic fibers. Collagen bundles are stained deep pink while elastic fibers are seen black in color. The photo was changed into gray scale 8-bit image (upper photo); then, segmentation of color was done to measure the percentage of elastic fibers (lower photo)

Fig. 2

Histopathologic specimens of abdominal skin biopsies in studied cases: A NSMWL group and B SMWL group. H&E-stained sections (× 100, scale bar = 200 microns) shows no difference in epidermal thickness in both groups. Masson trichrome staining (× 200, inset: × 100) shows blue stained collagen bundles in the dermis. Modified Verhoeff’s stain (× 200, inset: × 100) shows deep pink collagen bundles and black-colored elastic tissues. NSMWL group shows increased elasticity in comparison to the SMWL group

Fig. 3

Histopathologic assessment of breast skin biopsies in studied cases: A NSMWL group and B SMWL group. H&E-stained sections (× 100, scale bar = 200 microns) shows no difference in epidermal thickness in both groups. Masson trichrome staining (× 200, inset: × 100) shows blue-stained collagen bundles in the dermis. Modified Verhoeff’s stain (× 200, inset: × 100) shows deep pink collagen bundles and black-colored elastic tissues. No statistically difference in collagen and elastic tissues were detected between both groups