Tumoral calcium pyrophosphate dihydrate deposition disease. Report of a case with a review of the literature

Abstract

In a 56-year-old female patient with a mass at the proximal end of the left third finger for 22 years, the lesion enlarged obviously during the last 4 years. Initial diagnosis was chondroma with malignant change, and disarticulation of the finger was performed. Pathological diagnosis was "secondary chondrosarcoma". Microscopically, the mass contained a large amount of amorphous basophilic phosphate deposits surrounded by fibrous capsule. The pyrophosphate deposits consisted of birefringent needle shaped or rhomboid crystals which can be identified by polarizing microscope. It can be distinguished as tumoral calcium pyrophosphate dihydrate deposition disease, differing from tophaceous pseudogout, tumoral calcinosis and chondrocalcinosis. Nine cases were collected from the literature and the clinical, radiological and pathological features were discussed.