We studied senile purpura in 18 male subjects by calculating a half-life for intradermally injected autologous red blood cells (RBC) which had been labelled with sodium chromate Cr 51. There was no difference in half-life between the dorsal arm and ventral arm in elderly subjects who had spontaneous purpura on their dorsal arms. We found no difference between RBC halflife in older subjects and younger ones. The rate of removal was not altered by occlusion with tapes, ultraviolet light-induced erythema, or ingestion of bromelains. Histologic studies on biopsy specimens of induced purpuric lesions showed similar findings in both the older and the younger subjects.
Feinstein RJ, Halprin KM, Penneys NS, Taylor JR, Schenkman J. Senile Purpura. Arch Dermatol. 1973;108(2):229-232. doi:10.1001/archderm.1973.01620230029011