Three juvenile, genetically related African lions (Panthera leo) were evaluated for discrete dome-shaped subcutaneous masses present over the proximal metatarsus. The lesions measured 4–8 cm diameter, were fluctuant to firm, non-ulcerated, and attached to underlying structures. On radiographic evaluation, the lesions were characterized by well-circumscribed punctate mineralizations in the soft tissue lateral to the proximal fifth metatarsus with no evidence of bony involvement. On cut surface, the lesions consisted of numerous loculi containing 2–5 mm, white, round to ovoid firm structures interspersed with fibrous tissue and pockets of serosanguinous fluid. Hematology, serum biochemistry, baseline cortisol, serum thyroid screening (including total thyroxine, total triiodothyronine, free thyroxine, and free triiodothyronine), and serum vitamin D panels (including parathyroid hormone, ionized calcium, and 25-hydroxyvitamin D) were unremarkable. Aerobic culture of the lesions revealed no growth. Histopathologic evaluation of the lesions was consistent with calcinosis circumscripta with fibroplasia and associated granulomatous inflammation. Calcinosis circumscripta is an uncommon syndrome of the ectopic deposition of calcium salts in soft tissue structures.1 In veterinary medicine, these lesions occur most commonly on the footpads of the hind feet or under the tongue of large breed dogs less than 2 yr of age.1 Etiology is poorly understood, though repetitive trauma, insect bites, chronic renal failure, hereditary, and iatrogenic (especially excessive dietary vitamin D or calcium supplementation and vaccinations) causes have been implicated.1 To the authors’ knowledge, this is the first report of calcinosis circumscripta in a lion.
The authors thank the animal care staff at the National Zoological Park for their diligent work on this project and their unrelenting care for the lions in this study.
1. Tafti AK, Hanna P, Bourque AC. Calcinosis circumscripta in the dog: a retrospective pathological study. J Vet Med A Physiol Pathol Clin Med. 2005;52:13–17.