Skin biopsy (pink) and peripheral blood mononuclear cells (PBMCs) (light green) were collected. PBMC and skin-dissociated cells were incubated with ubiquitous antibodies conjugated with hashtag oligonucleotides (HTO) for cell hashing and with surface panel antibodies conjugated with ADT for ECCITE-seq. Stained and washed cells were loaded into 10× Chromium Single Cell Immune Profiling workflow (cells were individually encapsulated in droplets and lysed). Libraries were pooled and sequenced on Illumina platforms. After sequencing, bioinformatics analysis demultiplexed samples by their HTO. Malignant T cells were defined on their clonal TCRβ CDR3 sequence and on their distinct transcriptome and ADT. Then, transcriptional analysis defined clusters at the single-cell level from the same patient, and CNVs were inferred to build phylogenetic trees of subclones. Transcriptional trajectory analysis between blood and skin-derived malignant cells in the same patient revealed a marked proliferation and T-cell activation signature in the skin compartment.