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Bladder calcifications after photodynamic therapy: analysis of a rare complication
M M Walther1, E D Eanes, T F Delaney
1Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20898, USA.
Objectives:
We analyzed bladder calcifications occurring after photodynamic therapy administered for the treatment of superficial bladder cancer, a finding not previously reported after this treatment.
Methods:
Bladder biopsies from 20 patients undergoing photodynamic therapy were evaluated. Bladder calcifications were identified in 2 patients and analyzed for composition.
Results:
One patient had diffuse microcrystalline deposition in two biopsies composed of calcium oxalate monohydrate A. A second patient had a focal stone at a healing biopsy site composed of monoclinic calcium hydrogen phosphate dihydrate (brushite) (66%), calcium oxalate (25%), hydroxyapatite (6%), and protein (3%).
Conclusions:
Rare calcium oxalate and brushite calcifications were identified after photodynamic therapy and presumed to occur because of tissue injury associated with treatment.