Calcinosis circumscripta of the extremities and the tongue with multifocal arterial calcification secondary to chronic kidney disease in a cat

A 3-year-old neutered male mixed-breed cat was presented with right urinary tract obstruction caused by a urolith and severe atrophy of the left kidney. In the next year and a half, chronic kidney disease (CKD) progressed, and several masses were identified in the extremities, along with an ulcer on the tongue. Histologically, the extremity masses consisted of calcium deposits separated by fibrovascular septa, and the tongue ulcer showed severe neutrophilic infiltration with pervasive calcium deposition. These lesions were diagnosed as calcinosis circumscripta (CCs). Concurrently, multifocal mineralization of the aorta and of small- to medium-sized arteries in several organs indicated widespread vascular calcification. Both extremity and vascular lesions were likely secondary to the excessive calcium-phosphate product caused by CKD. Although CCs in either the extremities or tongue has been reported in cats, this case is notable for the presence of CCs in both extremities and tongue with systemic vascular calcification.