Impact of Needle Design and Suture Gauge on Tissue Tearing During Skin Suturing: A Comparative Analysis.

BACKGROUND: Surgeons face numerous choices in selecting sutures for skin closure, with potential adverse effects such as tissue tearing. OBJECTIVE: To investigate the influence of needle design and suture gauge on tissue tearing during suturing procedures. MATERIALS AND METHODS: The authors tested the tear-through force in Newtons for 3 needle types and 3 suture gauges using an artificial skin model and a professional-grade tensiometer. Suture material was secured into the skin model, and force was applied to the suture at a constant rate, resulting in tearing. Force-displacement and force-time curves were generated. Evaluation included conventional cutting (PC-3), reverse cutting (PS-3), and taper point (BB) needles with a 5-0 polypropylene suture. In addition, nylon sutures with a reverse cutting needle (PS-2) were tested at 3 suture gauges (5-0, 4-0, 3-0). RESULTS: The mean tear-through forces for PC-3, PS-3, and BB were 3.26 N, 3.75 N, and 4.07 N, respectively. For the 5-0, 4-0, and 3-0 nylon sutures, the mean tear-through forces were 3.44 N, 3.81 N, and 4.04 N, respectively. Statistical analysis revealed a significant impact of suture gauge size (p < .001) and needle geometry (p < .001) on tear-through force. CONCLUSION: Larger suture diameter and taper needles minimize tissue tearing.

Comparative Analysis of Taper Point and Reverse Cutting Needles on Skin Puncture Force.

BACKGROUND: Reverse cutting needles are commonly used in cutaneous surgery due to their perceived ease of use. Despite this, there is limited research evaluating the force required to puncture skin using contemporary needles. OBJECTIVE: This study aims to compare the puncture forces required for two different needle geometries across various gauge sizes. MATERIALS AND METHODS: The authors assessed the force necessary to penetrate samples of human abdominal skin samples using taper needles of three different United States Pharmacopeia gauge sizes with their respective reverse cutting needle counterparts. Taper point needles tested were RB-1 (3-0), TF (4-0), and C-1 (5-0), while reverse cutting needles included PS-2 (3-0) and P-3 (4-0, 5-0). An electronic force meter was used to record the puncture force required by each needle type. RESULTS: The mean puncture force in newtons (N) for taper point needles was 1.00, 0.74, and 0.48 for RB-1, TF, and C-1, respectively. The mean puncture force for reverse cutting needles was 0.95 N, 0.60 N, and 0.51 N for PS-2, P-3 (4-0), and P-3 (5-0), respectively. There was a direct relationship between needle body diameter and puncture force for both needle geometries. CONCLUSION: There was no clinically significant difference in skin puncture force between needle geometries.

The Effect of Preoperative Chlorhexidine Gluconate Cleanse on Lower Extremity Surgical Site Infections: A Retrospective Cohort Study.

BACKGROUND: Lower extremity surgical sites are at an increased risk of wound infection following Mohs micrographic surgery. OBJECTIVE: To evaluate the rate of lower extremity surgical site infections following a 14-day regimen of preoperative 4% chlorhexidine gluconate (CHG) rinses and postoperative wound occlusion for 14 days. MATERIALS AND METHODS: Retrospective data were collected from procedures performed by the senior author from January 2022 through June 2023. To meet inclusion, patients must have completed waist-down CHG soak and rinse for 14 days before surgery, including the day before surgery. In addition, the patient must have kept the dressing clean, dry, and intact until the postoperative appointment at 14 days. RESULTS: A total of 100 Mohs cases met inclusion criteria. Zero patients developed a surgical site infection. CONCLUSION: Chlorhexidine gluconate preoperative rinsing and postoperative occlusion for 14 days may minimize the risk of wound infection. Although further research is indicated, an opportunity exists for the adoption of CHG into routine clinical practice in the outpatient dermatology setting.

Reconstruction of High-Tension Scalp Defects by the Twizzler Technique: A Retrospective Case Series.

BACKGROUND: Scalp wounds are difficult to close primarily because of the inelasticity of the galea, often requiring adjacent tissue transfer or grafting. It is still debated whether intraoperative tissue expansion can occur on the scalp. OBJECTIVE: We report our experience with the Twizzler technique, a form of intraoperative tissue expansion and load cycling, to achieve primary closure of high-tension scalp wounds. MATERIALS AND METHODS: In this case series, scalp defects repaired by the Twizzler were identified and those with minimum 3 month follow-up underwent assessment by physicians and patients. RESULTS: All 50 scalp defects that could not be otherwise closed primarily were repaired successfully with the Twizzler. The average defect width was 2.0 cm (range 0.9-3.9 cm), the average physician aesthetic rating was 3.71 on a 5-point scale (very good; n = 25), and most patients rated the scars as "near normal skin" on the Patient and Observer Scar Assessment Scale 3.0 ( n = 32). CONCLUSION: Based on the findings of this case series, the Twizzler can be used to repair small and medium high-tension scalp defects after Mohs micrographic surgery. Intraoperative tissue expansion and creep deformation on the scalp is limited, but seemingly possible.

Superior Antihelix Composite Graft for Repair of Nasal Ala and Lateral Nasal Tip Defects: A Retrospective Case Series.

BACKGROUND: Deep defects on the nasal ala and lateral nasal tip may result in nasal valve insufficiency or alar notching and are often repaired with a 2-stage reconstruction. Previous literature has demonstrated high failure rates of composite grafts. OBJECTIVE: Identify survival rates and cosmetic outcomes of nasal composite grafts harvested from the antihelix. METHODS: A retrospective review of 52 patients who underwent ala or lateral nasal tip composite graft repair from April 2019 through May 2022, with statistical analysis of cosmetic outcomes graded by 2 surgeons. RESULTS: Defect size ranged from 0.7 cm × 0.8 cm to 1.9 cm × 2.5 cm. 48 grafts survived (92.3% survival rate). Four patients sustained at least partial integument sloughing (epidermal necrosis), but the cartilage survived in all 52 cases. Overall, aesthetic results yielded the following: excellent (19.5%), very good (35.5%), good (11.5%), decent (16.5%), and poor (6%). In 93% of cases, there was no evidence of nasal collapse or retraction. Two patients (3.8%) required surgical revision. Donor site morbidity was low. CONCLUSION: The antihelical composite skin graft is a 1-step reliable repair option for ala and lateral nasal tip defects with an acceptable cosmetic outcome.

Plume Generated by Different Electrosurgical Techniques: An In Vitro Experiment on Human Skin.

BACKGROUND: Plume generated by electrosurgical techniques is a health hazard to patients and dermatologists. OBJECTIVE: To compare the particle concentration generated by various energy devices used in dermatologic surgery. MATERIALS AND METHODS: Five surgical techniques were tested on human tissue samples in a closed chamber. A particle counter, positioned at a fixed point 20 cm away from the sample, recorded the concentrations of aerosolized particles generated over 7 particle sizes (0.3, 0.5, 0.7, 1, 2.5, 5, and 10 µm). RESULTS: Monopolar electrocoagulation created the greatest concentration of particles followed by electrocautery, electrodesiccation, electrofulguration, and bipolar electrocoagulation. Bipolar electrocoagulation created 80 times fewer 0.3 µm particles and 98 times fewer 0.5 µm particles than monopolar electrocoagulation. Across all electrosurgical techniques, the greatest concentrations of particles generated were of the 0.3 and 0.5 µm particle size. CONCLUSION: Bipolar electrocoagulation created the lowest concentration of particulate matter. Given the noxious and hazardous nature of surgical plume, the bipolar forceps offer surgeons a safer method of performing electrical surgery for both the surgical staff and the patient.

The Twizzler: a modified primary closure for distal lower extremity wound reconstruction utilizing a dynamic winch stitch.

Management of lower extremity wounds following successful tumor excision presents multiple challenges. Distal lower extremity integument is highly prone to edema often lacks adequate skin laxity for standard primary closures. The closure must be resilient enough to withstand mobility. As a result, optimal reconstruction may include skin grafting, rotational flaps, free tissue transfers, healing by second intention, or some combination. These methods may involve multiple steps in reconstruction, a prolonged recovery period, increased cost, and higher infection risk. We propose a modified primary closure that takes advantage of the visco-elastic properties of the skin without introducing additional components or steps. This technique is initiated with percutaneous suture in order to intermittently stretch the skin with constant tension. This load cycling allows for lower extremity skin to stretch over time and ultimately reduce wound edge tension, allowing for ease of absorbable suture placement. The Twizzler technique is cost-effective, uses readily available supplies, and effectively closes relatively large defects on the lower extremities.

Tumor-specific T cells in human Merkel cell carcinomas: a possible role for Tregs and T-cell exhaustion in reducing T-cell responses.

Merkel cell carcinomas (MCCs) are rare but highly malignant skin cancers associated with a recently described polyomavirus. MCC tumors were infiltrated by T cells, including effector, central memory, and regulatory T cells. Infiltrating T cells showed markedly reduced activation as evidenced by reduced expression of CD69 and CD25. Treatment of MCC tumors in vitro with IL-2 and IL-15 led to T-cell activation, proliferation, enhanced cytokine production, and loss of viable tumor cells from cultures. Expanded tumor-infiltrating lymphocytes showed TCR repertoire skewing and upregulation of CD137. MCC tumors implanted into immunodeficient mice failed to grow unless human T cells in the tumor grafts were depleted with denileukin diftitox, suggesting that tumor-specific T cells capable of controlling tumor growth were present in MCC. Both CD4(+) and CD8(+) FOXP3(+) regulatory T cells were frequent in MCC. Fifty percent of nonactivated T cells in MCC-expressed PD-1, a marker of T-cell exhaustion, and PD-L1 and PD-L2 were expressed by a subset of tumor dendritic cells and macrophages. In summary, we observed tumor-specific T cells with suppressed activity in MCC tumors. Agents that stimulate T-cell activity, block regulatory T cell function, or inhibit PD-1 signaling may be effective in the treatment of this highly malignant skin cancer.

Imiquimod enhances IFN-gamma production and effector function of T cells infiltrating human squamous cell carcinomas of the skin.

Squamous cell carcinomas (SCCs) are sun-induced skin cancers that are particularly numerous and aggressive in patients taking T-cell immunosuppressant medications. Imiquimod is a topical immune response modifier and Toll-like receptor 7 (TLR7) agonist that induces the immunological destruction of SCC and other skin cancers. TLR7 activation by imiquimod has pleiotropic effects on innate immune cells, but its effects on T cells remain largely uncharacterized. Because tumor destruction and formation of immunological memory are ultimately T-cell-mediated effects, we studied the effects of imiquimod therapy on effector T cells infiltrating human SCC. SCC treated with imiquimod before excision contained dense T-cell infiltrates associated with tumor cell apoptosis and histological evidence of tumor regression. Effector T cells from treated SCC produced more IFN-gamma, granzyme, and perforin and less IL-10 and transforming growth factor-beta (TGF-beta) than T cells from untreated tumors. Treatment of normal human skin with imiquimod induced activation of resident T cells and reduced IL-10 production but had no effect on IFN-gamma, perforin, or granzyme, suggesting that these latter effects arise from the recruitment of distinct populations of T cells into tumors. Thus, imiquimod stimulates tumor destruction by recruiting cutaneous effector T cells from blood and by inhibiting tonic anti-inflammatory signals within the tumor.

Human squamous cell carcinomas evade the immune response by down-regulation of vascular E-selectin and recruitment of regulatory T cells.

Squamous cell carcinomas (SCCs) of the skin are sun-induced skin cancers that are particularly numerous in patients on T cell immunosuppression. We found that blood vessels in SCCs did not express E-selectin, and tumors contained few cutaneous lymphocyte antigen (CLA)(+) T cells, the cell type thought to provide cutaneous immunosurveillance. Tumors treated with the Toll-like receptor (TLR)7 agonist imiquimod before excision showed induction of E-selectin on tumor vessels, recruitment of CLA(+) CD8(+) T cells, and histological evidence of tumor regression. SCCs treated in vitro with imiquimod also expressed vascular E-selectin. Approximately 50% of the T cells infiltrating untreated SCCs were FOXP3(+) regulatory T (T reg) cells. Imiquimod-treated tumors contained a decreased percentage of T reg cells, and these cells produced less FOXP3, interleukin (IL)-10, and transforming growth factor (TGF)-beta. Treatment of T reg cells in vitro with imiquimod inhibited their suppressive activity and reduced FOXP3, CD39, CD73, IL-10, and TGF-beta by indirect mechanisms. In vivo and in vitro treatment with imiquimod also induced IL-6 production by effector T cells. In summary, we find that SCCs evade the immune response at least in part by down-regulating vascular E-selectin and recruiting T reg cells. TLR7 agonists neutralized both of these strategies, supporting their use in SCCs and other tumors with similar immune defects.

Blood exposure risk during procedural dermatology.

BACKGROUND: Dermatologists are at risk of body-fluid contamination during procedures. OBJECTIVE: We sought to determine the frequency of blood splash during procedural dermatology. METHODS: In all, 500 consecutive excisions were performed. Postoperatively, blood droplets on face shields and surgical gowns were counted. A survey regarding universal precautions during procedures was also conducted with members of the American College of Mohs Surgery (ACMS). RESULTS: Contamination from blood splashes during dermatologic procedures (Mohs micrographic surgery, excision, repair) occurred in 66.4%. Reconstruction type, anticoagulation use, wound location, and wound size correlated with a higher blood splash rate. Our survey showed that face shields and goggles are used inconsistently. LIMITATIONS: The 4 participating dermatologists do not represent all practicing dermatologists. It may be possible to generalize the survey results directed at physicians in the ACMS. CONCLUSION: Physician body-fluid contamination risk with procedural dermatology is clinically significant. Dermatologists and their assistants should wear preventive barriers during procedures to minimize the risk of viral transmission.

Central role of p53 in the suntan response and pathologic hyperpigmentation.

UV-induced pigmentation (suntanning) requires induction of alpha-melanocyte-stimulating hormone (alpha-MSH) secretion by keratinocytes. alpha-MSH and other bioactive peptides are cleavage products of pro-opiomelanocortin (POMC). Here we provide biochemical and genetic evidence demonstrating that UV induction of POMC/MSH in skin is directly controlled by p53. Whereas p53 potently stimulates the POMC promoter in response to UV, the absence of p53, as in knockout mice, is associated with absence of the UV-tanning response. The same pathway produces beta-endorphin, another POMC derivative, which potentially contributes to sun-seeking behaviors. Furthermore, several instances of UV-independent pathologic pigmentation are shown to involve p53 "mimicking" the tanning response. p53 thus functions as a sensor/effector for UV pigmentation, which is a nearly constant environmental exposure. Moreover, this pathway is activated in numerous conditions of pathologic pigmentation and thus mimics the tanning response.