Differential Diagnosis for Bony Superficial Swelling in the Foot of a Child

Age-Stratified Differential Diagnosis

In children under 5 years, metastatic neuroblastoma is the most common destructive bone lesion, while eosinophilic granuloma represents the other primary consideration for destructive lesions 1, 2
In children over 5 years, osteosarcoma is the most frequent primary bone cancer, with a peak incidence in adolescents, accounting for more than 10% of all solid cancers in this age group 1, 2
Ewing sarcoma is the third most common primary malignant bone tumor, with a median age at diagnosis of 15 years, and approximately 50% involve extremity bones 1, 2

Persistent non-mechanical pain lasting more than a few weeks should cause immediate concern and warrant further investigation, according to the American College of Oncology 3, 1
Night pain is particularly concerning for malignancy, as stated by the American College of Oncology 3, 1
Visible swelling indicates the tumor has progressed through the cortex and distended the periosteum, as noted by the American College of Oncology 3, 1
Recent trauma does not rule out malignancy and must not prevent appropriate diagnostic procedures, as recommended by the American College of Oncology 3, 1

Obtain conventional radiographs in two planes as the first investigation in all cases, as suggested by the American College of Radiology 3, 1, 4
Look for bone destruction, periosteal reaction, new bone formation, and soft tissue swelling, as recommended by the American College of Radiology 5
Proceed to MRI of the whole compartment with adjacent joints if radiographs cannot exclude malignancy with certainty, as stated by the American College of Radiology 3, 1
MRI is the best modality for local staging of extremity tumors, according to the American College of Radiology 3, 1
CT should be reserved for diagnostic problems or to visualize calcification, periosteal bone formation, or cortical destruction more clearly, as recommended by the American College of Radiology 3, 1

All patients with suspected primary malignant bone tumor must be referred to a bone sarcoma reference center BEFORE biopsy, as recommended by the American College of Oncology 3, 1, 5
Biopsy should only be performed by the surgeon who will perform definitive resection if malignancy is confirmed, as stated by the American College of Surgeons 5
Inappropriate biopsy can compromise treatment outcomes, as noted by the American College of Surgeons 5