Parameters Characteristic of Upper Dermal Microvasculature in Patients after Hematopoietic Cell Transplantation by Noninvasive Reflectance Confocal Videomicroscopy.

We noninvasively visualized the upper dermal microvasculature of 31 patients after hematopoietic cell transplantation (HCT) by reflectance confocal videomicroscopy. The microvessel diameter and number and diameter of adherent and rolling leukocytes for patients after HCT were similar to historically published values in healthy subjects. We also observed "paused" leukocytes i.e. leukocytes that temporarily stop, coinciding with the simultaneous stopping of the rest of the blood flow. The number and diameter of paused leukocytes, and the duration of leukocyte being paused for patients after HCT were also similar to historically published values in healthy subjects. However, we observed more blood vessels per imaging field of view (500 × 500 μm2) in the skin of patients after HCT than healthy subjects (a median of 3 versus 2). The number of blood vessels in a field of view was not correlated with the number of adherent and rolling leukocytes. Vessel size (flow width) had a meaningful correlation with the diameter, but not number, of paused leukocytes. Paused leukocyte diameter had no correlation with the duration of pausing. Reflectance confocal videomicroscopy enables characterization of intact upper dermal microvasculature of patients with extremely altered immune system.