Kit (QIAGEN) per the manufacturer's instructions, with overnight tissue digestion. This method generated 155-3730 ng DNA per sample.HTS analyses: immunosequencing. For each sample, DNA was extracted from skin biopsies, then TCRβ CDR3, TCRγ CDR3, TCRα CDR3, and TCRδ CDR3 regions were amplified and sequenced using immunoSEQ (Adaptive Biotechnologies). Bias-controlled V and J gene matitis, allergic contact dermatitis, and pityriasis lichenoides were obtained with IRB approval from the Pathology Specimen Locator Core at Brigham and Women's Hospital.DNA isolation from skin. DNA was isolated from frozen, OCTembedded skin samples. 30 Cryosections of 10-μm thickness were cut, and DNA extraction was carried out using the QIAamp DNA Mini