The genetic background of a previously undescribed manifestation in a Gorlin-Goltz syndrome (including skin basal cell carcinomas and multiple developmental abnormalities) patient is presented: two-sided PEComas (perivascular epitheloid cell tumors) next to the adrenal glands. A novel germ-line mutation of the PTCH1 tumor suppressor gene was identified. Surprisingly, the same somatic mutation (a five nucleotide deletion) in PTCH1 was found in the tissue samples from both tumors. A hypothesis is presented that the origin of this phenomenon might be related to a mutation in the early embryogenesis (early postzygotic mutation) that would explain how the same mutation could occur in both tumors via type 2 segmental mosaicism (Figure). (By Dr. Peter Igaz, https://jmg.bmj.com/content/early/2021/12/15/jmedgenet-2021-108082 )