Persistent and late occurring lesions in irradiated feet of rats: their clinical relevance.

Radiation-induced deformity, as characterized by tissue loss, has been investigated in rat feet. The acute epithelial response and the loss of deeper tissues occur concomitantly after irradiation. The greatest loss of tissue (severe deformity) was produced in feet where the healing of the epithelial reaction was greatly delayed. While deformity will clearly continue to "persist" after the acute reaction has healed it is misleading to refer to this lesion as "late" damage. A late-occurring lesion, not previously described in the literature, can be produced in the rat foot by high doses of radiation delivered in such a way that moist desquamation is avoided, i.e. by extending the total treatment time. The "persistent" and "late" radiation lesions are discussed in relation to other published data on the radiation response of rodent skin in the foot, ear and tail. Parallels are also drawn between reactions in rodents and those in the skin of pig and man.