BACKGROUND:The arrector pili muscle (APM) is a key structural component of the pilosebaceous unit and follicular stem cell niche. However, its fate after hair transplantation (HT) remains poorly understood. OBJECTIVE:To histologically assess APM preservation in transplanted hair follicles (HFs). METHODS:Scalp biopsies from recipient and native donor areas of 5 patients with suboptimal graft survival after HT were analyzed. Two 4-mm punch biopsies were obtained in each case for horizontal and vertical sectioning. The presence of APMs associated with follicular units (FUs), proximal and distal APM attachment sites, and peri-APM inflammation were evaluated. RESULTS:A total of 78 FUs were examined. In recipient areas after FU excision (FUE) and FU transplantation, identifiable APMs were associated with 17.2% and 30.0% of FUs, respectively, compared with 25.6% in native occipital donor areas. Although identified muscle fibers appeared continuous, normal proximal and distal attachment sites were not visualized in any specimen. CONCLUSION:Transplanted HFs may persist despite absent or disrupted APM architecture, suggesting that complete preservation of native APM anatomy may not be essential for ongoing HF survival after HT.
BACKGROUND:Microneedling is gaining popularity in dermatologic practice to enhance transdermal drug delivery, yet key determinants of its efficacy-microneedle characteristics, drug properties, and the sequence of drug application-remain poorly understood. OBJECTIVE:The authors conducted a systematic review and meta-analysis to identify factors affecting efficacy of microneedling-assisted drug delivery measured using biochemical (Franz diffusion studies) or visual (histology and advanced imaging) methods. MATERIALS AND METHODS:PubMed, Web of Science, and Cochrane Library were searched through May 1, 2025. Data were abstracted on microneedling characteristics, treatment sequences, and drug characteristics. The authors performed a meta-analysis of Franz diffusion experiments to evaluate the efficacy and meta-regression to identify microneedle or drug factors influencing the efficacy. RESULTS:Twenty-nine articles were included. Microneedling enhances drug delivery (standard mean difference [95% confidence interval], 4.61 [2.99-6.24]). Delivery was greater for hydrophilic drugs (6.56 [2.28-10.85]) than for hydrophobic drugs (3.49 [2.43-4.56]) (p = .014). Longer needle lengths (≥500 μm; 5.96 [3.33-8.60] vs 2.77 [2.05-3.49] for <500 μm, p = .02) and drug application before microneedling (1.64 [1.00-2.28] vs 0.38 [-0.24 to 1.00] for drug after microneedling, p = .01) increased drug delivery. CONCLUSION:Clinicians should consider needle length, drug hydrophilicity, and treatment sequence to enhance microneedling-assisted drug delivery.
BACKGROUND Induction immunosuppression reduces early rejection after solid organ transplantation but may increase long-term malignancy risk, including keratinocyte carcinoma. Antithymocyte globulin is commonly used as a lymphocyte-depleting induction agent, yet its relative risk compared with other strategies remains unclear. OBJECTIVE To evaluate the association between antithymocyte globulin induction therapy and keratinocyte carcinoma risk in adult solid organ transplant recipients compared with no induction, nondepleting agents, and other lymphocyte-depleting therapies. METHODS PubMed, EMBASE, and MEDLINE were searched from January 1997 to February 2024. Observational studies and randomized trials reporting keratinocyte carcinoma outcomes in adult recipients exposed to antithymocyte globulin were included. Risk of bias was assessed using validated tools. Random-effects meta-analyses using risk ratios with 95% confidence intervals were performed. RESULTS Twelve studies including 56,159 recipients with a weighted mean follow-up of 7.27 years were analyzed. Antithymocyte globulin induction was not associated with increased keratinocyte carcinoma risk compared with no induction. Lower risk was observed compared with alemtuzumab and OKT3. No significant difference in risk was observed compared with nondepleting anti-CD25 agents. CONCLUSION Antithymocyte globulin induction does not increase keratinocyte carcinoma risk compared with no induction and is associated with lower risk than more potent lymphocyte-depleting agents after solid organ transplantation.
BACKGROUND:Merkel cell carcinoma (MCC) is a highly aggressive cutaneous malignancy. Guidelines recommend surgical excision with histologically negative margins for clinically node-negative disease. Adjuvant radiation therapy (aRT) is recommended for positive margins; however, its ability to offset the adverse impact of residual microscopic disease remains uncertain. OBJECTIVE:Evaluate the association between surgical margin status and oncologic outcomes among patients treated with excision and aRT. METHODS:Using the National Cancer Database (2004-2022), the authors identified patients with cN0 MCC who underwent excision followed by aRT with documented margin status. Multivariable logistic regression assessed predictors of regional lymph node metastasis, and Cox modeling evaluated all-cause mortality. RESULTS:Among 7,510 patients, 11.7% had positive surgical margins. Margin positivity was more common in older patients, head and neck tumors, and higher T-stage disease. Positive margins were independently associated with increased odds of regional lymph node metastasis (aOR 1.57, 95% confidence interval CI 1.24-1.99; p < .001) and higher all-cause mortality (HR 1.60, 95% CI 1.43-1.78; p < .001). CONCLUSION:Their findings suggest that positive surgical margins are an adverse prognostic factor despite aRT. Achieving histologically negative margins remains an important prognostic consideration in the management of MCC.
