Nail-patella syndrome associated with mixed crystal deposition arthropathy.

This report describes a case of nail-patella syndrome in a woman with a strong family history who presented with effusions in her shoulder and knees. Microscopic examination of the shoulder fluid suggested the presence of calcium pyrophosphate dihydrate (CPPD) crystals, and examination of the knee fluid suggested both hydroxyapatite (HAP) and CPPD crystals. To our knowledge, the coexistence of these two conditions has not been reported in the past. Moreover, it brings up a new element regarding the inflammatory origin of the nail-patella syndrome.