Rate and Characteristics of Incompletely Excised Cutaneous Squamous Cell Carcinoma: A Dermatological Daily Practice Multicenter Prospective Cohort Study.

BACKGROUND: Incomplete excision of squamous cell carcinoma (cSCC) is associated with an increased risk of recurrence, metastasis, and mortality. OBJECTIVE: To determine the rate and characteristics of incompletely excised cSCC in a dermatological daily practice setting. METHODS: Prospective study of all patients who gave informed consent, with a cSCC treated with standard excision (SE) at 1 of 6 Departments of Dermatology in the Netherlands between 2015 and 2017. Pathological reports were screened to detect all incompletely excised cSCCs. RESULTS: A total of 592 patients with 679 cSCCs were included, whereby most cases were low risk cSCC (89%). The rate of incompletely excised cSCC was 4% ( n = 26), and the majority were high-risk cSCCs of which 24 invaded the deep excision margin. CONCLUSION: This prospective study showed that in a dermatological setting, the risk of an incompletely excised cSCC is low (4%) for a cohort that was dominated by low-risk cSCCs. Most incompletely excised cSCCs were of high risk, and incompleteness was almost always at the deep margins. These results suggest that for high-risk cSCC, one should pay attention especially to the deep margin when performing SE, and/or microscopic surgery should be considered.

Gold Chain Formation via Local Lifting of Surface Reconstruction by Hot Electron Injection on H2(D2)/Au(111).

The hexagonal close packed surface of gold shows a 22 × 3 "herringbone" surface reconstruction which makes it unique among the (111) surfaces of all metals. This long-range energetically favored dislocation pattern appears in response to the strong tensile stress that would be present on the unreconstructed surface. Adsorption of molecular and atomic species can be used to tune this surface stress and lift the herringbone reconstruction. Here we show that herringbone reconstruction can be controllably lifted in ultrahigh vacuum at cryogenic temperatures by precise hot electron injection in the presence of hydrogen molecules. We use the sharp tip of a scanning tunneling microscope (STM) for charge carrier injection and characterization of the resulting chain nanostructures. By comparing STM images, rotational spectromicroscopy and ab initio calculations, we show that formation of gold atomic chains is associated with release of gold atoms from the surface, lifting of the reconstruction, dissociation of H2 molecules, and formation of surface hydrides. Gold hydrides grow in a zipper-like mechanism forming chains along the [11̅0] directions of the Au(111) surface and can be manipulated by further electron injection. Finally, we demonstrate that Au(111) terraces can be transformed with nearly perfect terrace selectivity over distances of hundreds of nanometers.