A pluripotent potential was also consistent with the strong positivity of the endothelia for CD34, a sialomucin also expressed in mesenchymal progenitors and in gastrointestinal stromal tumors (GISTs), which co-occur with PGL in some SDH-related PGL syndromes [46,60], and for β2-microglobulin, a major histocompatibility complex (MHC) class I component associated with infection, the EMT, and cancer [61]. Here, SDHB is linked to cancer.