My husband noticed a hard lump on his left shin bone today. he is wondering what it could be. he has no pain, no specific injury remembered?

Should get X-ray: There are a number of reasons for bumps on bone, trauma is one, other causes are benign or malignant. Benign causes include endochondroma, osteochondroma, nonossifying fibroma, chondroblastoma, osteoid osteoma, osteoblastoma, periosteal chondroma, giant cell tumor, and chondromyxoid fibroma. Malignant lesions in that age range include osteosarcoma, chondrosarcoma or ewing's sarcoma. See a md.