This is a guess, but perhaps the result of an infection by a fungal plant pathogen related to Taphrina deformans. T deformans infects species of the genus Prunus (i.e. the genus of prunes and apricots), but is is best known for causing peach leaf curl in another Prunus species, peaches.
For example, see this image of T. deformans infecting a leaf in Catalonia, Spain:
[![enter image description here][1]][1]
Source: flickriver; Credit: esat_ahi
From Wikipedia:
trees infected with T. deformans will experience leaf puckering and distortion, acquiring a characteristic downward and inward curl. Leaves will also undergo chlorosis, turning a pale green or yellow, and later show a red or purple tint
Are yo usure your infected plant part is a fruit and not a grossly infected leaf? (Did you cut open the infected fruit to examine it closer)? [1]: https://i.sstatic.net/Rnxyw.png
