Three juvenile, genetically related African lions (Panthera leo) were evaluated for discrete dome-shaped subcutaneous masses present over the proximal lateral metatarsal-tarsal area. The lesions measured 3-8 cm in diameter, were fluctuant to firm, nonulcerated, and attached to underlying structures. On radiographic evaluation, the lesions were characterized by well-circumscribed punctate mineralizations in the soft tissue surrounded by soft tissue swelling without evidence of adjacent bony involvement. On cut surface, the lesions were made of numerous loculi containing 2-5-mm round-to-ovoid, white-to-gray, firm structures interspersed with fibrous tissue and pockets of serosanguinous fluid. Hematology, serum biochemistry, 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. Histopathologic evaluation of the lesions was consistent with calcinosis circumscripta with fibroplasia, chronic inflammation, and seroma formation. An additional two genetically related lions were considered suspect for calcinosis circumscripta based on presentation, exam findings, and similarity to the confirmed cases. All masses self-regressed and were not associated with additional clinical signs other than initial lameness in two cases.
Keywords: Calcinosis circumscripta; Panthera leo; lion; skin; tumoral calcinosis.