Photoreceptor rosettes in autosomal dominant retinitis pigmentosa with reduced penetrance

We performed histopathologic and immunofluorescence studies of autopsy eyes from a 73-year-old woman with autosomal dominant retinitis pigmentosa from a family with reduced penetrance. Light microscopic examination showed ext ensive photoreceptor loss in most regions. In the temporal midperiphery of the retina, there were patches of remaining photoreceptors, some arranged i n rosettes. Electron microscopic examination showed that these rosettes wer e composed mostly of rods, with a few conelike inner segments. The malforme d photoreceptor elements in the rosette lumens stained positively with anti -rhodopsin, but not with anti-red- and green-cone opsin or anti-blue-cone o psin. To our knowledge, this is the first report of photoreceptor rosettes containing rod photoreceptors in a case of retinitis pigmentosa. Future stu dies of additional patients will be needed to determine if the rod-abundant rosettes seen in our patient are a characteristic finding of autosomal dom inant retinitis pigmentosa with reduced penetrance.