Solitary Enchondroma

There is an expansile, lucent, well-defined ("geographic") lesion with swirls and rings of chondroid calcification at the base of the proximal phalanx of the right 4th digit.
Pathologic fracture is present.

Findings are compatible with a benign solitary enchondroma of bone.

You may wish to review some facts concerning enchondromas:

May be solitary or multiple.
- Ollier's Disease when multiple.
- Maffucci's Syndrome when accompanied by S.T. hemangiomas.
M=F.
Asymptomatic or painless S.T.S.
40-60% of solitary lesions occur in hands (usually metaphyseal).
- Most common benign tumor of hand.
- Frequency:
  - proximal phalanges
  - metacarpals
  - middle phalanges
25% in humerus, femur, tibia.
Radiographically, a lucent expansile lesion with "chondroid" calcifications.
- Calcification not invariable.
- May present with fracture.
Malignant transformation (usually to chondrosarcoma) can occur, usually in pelvis, shoulder.
- Rare in small bones of hands and feet.
- Changes in the clinical or radiographic appearance may indicate malignancy.
- The larger a cartilaginous lesion is, the more likely it is to be malignant.
- Solitary enchondromas rare in pelvis -- a common location for chondrosarcomas.

Case courtesy Drs. Chris Petti and Steve Yaron (Residents, 1996), Dept. Radiology, SUNY HSCB.

Ref: Resnick, D., Bone and Joint Imaging, W.B. Saunders, Philadelphia, PA, 1989, pp. 1126-1128.