As a primary care physician, should I refer a patient with a benign femoral enchondroma to orthopedics and also to oncology?

Referral Decision for Benign Femoral Enchondroma

You were partially correct: orthopedic referral is appropriate for a femoral enchondroma, but oncology referral is premature and unnecessary at this stage unless specific red flags are present. 1

Why Orthopedic Referral is Appropriate

The femur is a high-risk anatomical site for enchondromas, with malignant transformation to chondrosarcoma occurring in approximately 30% of patients with enchondromatosis syndromes (though solitary lesions carry much lower risk). 1 Even for benign-appearing lesions, orthopedic involvement is warranted because:

• Location matters critically: Femoral enchondromas, particularly those in the proximal femur (neck/head), carry markedly increased concern for malignancy compared to lesions in small bones of hands/feet where malignancy is extremely rare. 1, 2

• Diagnostic uncertainty is substantial: Differentiating a benign enchondroma from an atypical cartilaginous tumor/grade I chondrosarcoma is notoriously difficult even for expert pathologists, with radiographs correctly identifying enchondroma in only approximately 67% of cases. 1, 2

• Surveillance requirements: Orthopedic surgeons with musculoskeletal-tumor expertise should schedule serial radiographs every 2-3 years for known femoral enchondromas to monitor for changes. 1, 3

When Oncology Referral Becomes Necessary

Direct oncology referral is indicated only when malignancy is suspected based on specific clinical or imaging red flags. 1 The critical distinction is that benign enchondromas do not require oncology evaluation—they need orthopedic monitoring.

Red Flags Requiring Immediate Sarcoma Center Referral (Not General Oncology):

• New or worsening pain localized to the lesion site (most important clinical indicator of possible malignancy) 1, 4
• Lesion size greater than 5-6 cm in any femoral region 1, 3
• Aggressive radiographic features: cortical scalloping, erosion, lytic areas, cortical breaks, or soft-tissue extension 1
• Radiographic evidence of growth on serial imaging 3

Critical Pathway Point:

If malignancy is suspected based on clinical or imaging findings, patients must be referred to a bone-sarcoma reference center BEFORE any biopsy is performed—not to general oncology. 5, 1 This is because improper biopsy technique can contaminate tissue planes and compromise definitive surgical treatment.

The Correct Referral Algorithm

Immediate Orthopedic Referral Indicated When:

• Any femoral enchondroma (given the high-risk location) 1
• Symptomatic lesion with pain at the tumor site 1
• Lesion size >3-5 cm 1
• Lesion located in femoral neck or head 1
• Any aggressive radiographic features 1

Observation by Primary Care May Be Considered Only When:

• Completely asymptomatic incidental finding 1
• Small lesion (<3 cm) in femoral diaphysis 1
• Classic benign radiographic appearance with punctate calcifications 1
• However, even in these cases, establishing an orthopedic relationship is prudent given the femoral location and long-term transformation risk 1

Specialized Sarcoma Center Referral (Not General Oncology) When:

• Clinical red flags present (pain, growth, size >5-6 cm) 1, 3
• Imaging suggests malignancy 5, 1
• Before any biopsy is contemplated 5, 1

Common Pitfall You Encountered

Referring to general oncology for a benign lesion creates unnecessary patient anxiety and healthcare inefficiency. 6 Enchondromas are among the "top five lesions that do not need referral to orthopedic oncology" when they meet benign criteria—and certainly don't require medical oncology evaluation unless malignancy is confirmed or strongly suspected. 6

The appropriate pathway is: Primary Care → Orthopedic Surgeon (preferably with musculoskeletal tumor expertise) → Bone Sarcoma Center (only if red flags develop). 5, 1

What You Should Do Now

• Maintain the orthopedic referral for surveillance planning and risk stratification 1
• Contact the oncology office to explain the referral may have been premature unless specific red flags are present that you haven't mentioned 1
• Ensure the orthopedic surgeon has musculoskeletal tumor experience or access to a sarcoma MDT for consultation if needed 5