A focal, necrotic soft tissue mass was diagnosed on the left forelimb of an adult, wild, intact female bog turtle (Glyptemys muhlenbergii). Excisional biopsy revealed a soft tissue sarcoma, and a full limb amputation was performed. Because mesenchymal tumors are rarely reported in chelonians, this case demonstrates that neoplasia should be considered as a differential for subcutaneous masses even in wild turtles. This is the first report of a soft tissue sarcoma in the genus Glyptemys. To the authors' knowledge, this is only the second case report of a soft tissue sarcoma reported in the Order Testudines.