Calcium pyrophosphate dihydrate deposition disease presenting as tumoral calcinosis (periarticular pseudogout).

It has been considered unusual for periarticular calcifications to consist of calcium pyrophosphate dihydrate (CPPD). We describe a patient presenting with pain and inflammation adjacent to the site of tumoral calcifications and extending to the first metatarsophalangeal joint. Aspiration of the material revealed weakly positive birefringent rhomboid shaped crystals that proved to be CPPD by atomic force microscopy. The patient had no metabolic abnormalities or radiographic chondrocalcinosis. We believe other cases similar to ours represent another clinical form of CPPD deposition disease-periarticular pseudogout.