Enchondroma

Clinical Presentation

• Often      asymptomatic, detected incidentally (except in hand lesions).

• Hand      enchondromas: Pain due to bone expansion, cortical thinning, or      microfractures.

• Long      bone enchondromas with pain: Rule out first intra-articular pathologies, atypical      cartilage tumor or chondrosarcoma

Associated Syndromes

• Ollier’s      disease: Multiple enchondromas, unilateral, 20-50% malignant      transformation risk. Lesions are generally unilateral. Short stature, limb      length discrepancy, and angular deformities in bones and joints are      commonly seen.

• Maffucci      syndrome: Enchondromas + soft tissue hemangiomas; higher malignancy      risk than Ollier’s. Due to      phleboliths, hemangiomas are also detected on X-rays.

Common Sites

• Hands      (40-65%): Proximal phalanges > metacarpals > middle phalanges.

• Long      bones: Femur, humerus, tibia (metaphyseal).

• Rare      in carpal/tarsal bones or distal phalanges.

Imaging Features

• X-ray:

  • Hands: Lytic,       sclerotic rim, bone expansion, cortical thinning, calcification is not       usually seen.

  • Long       bones: Metaphyseal, indistinct margins, endosteal scalloping,       matrix calcification.

• CT: Evaluates      calcification and cortical integrity.

• MRI: Assesses      soft tissue extension, peritumoral edema, contrast enhancement (for      differential diagnosis) and fat entrapment.

• PET-CT: Useful      for enchondromatosis/pelvic lesions

Biopsy

• Not      routine; reserved for atypical features (e.g., pain, growth, or imaging      suspicious for chondrosarcoma).

• Target      less calcified, fat entrapment and heterogeneous areas on MRI. Biopsy      tract should align with potential surgical incision.

Treatment

• Asymptomatic,      small (<4 cm), stable lesions: Annual monitoring.(BACTIP Protocole* : Birmingham Atypical Cartilage Tumor Imaging Protocol)

• Surgical      indications:

  • Pain,       growth on follow-up, or pathologic fracture risk.

  • Techniques: Intralesional       curettage + adjuvant + bone-filler (PMMA/graft) ± fixation (fracture risk       in lower extremities).

  • Hand       lesions: Curettage alone/ Curettage and bone filler (PMMA/Graft)

Differential Diagnosis

• Atypical      Cartilage Tumor (ACT):

  • WHO       2020 reclassified grade I chondrosarcomas in extremities as ACT (no metastasis risk but can recur).

  • Suspect       if pain, size >4 cm, generalized endosteal scalloping.

• Chondrosarcoma:

  • Cortical       destruction, soft tissue involvement, axial skeleton location.