Differential Diagnosis of Solitary Lucent Bone Lesions

Mnemonic = FOGMACHINES

Differential Diagnosis of Solitary Lucent Bone Lesions

• Fibrous Dysplasia
• Osteoblastoma
• Giant Cell Tumor
• Metastasis / Myeloma
• Aneurysmal Bone Cyst
• Chondroblastoma / Chondromyxoid Fibroma
• Hyperparathyroidism (brown tumors) / Hemangioma
• Infection
• Non-ossifying Fibroma
• Eosinophilic Granuloma / Enchondroma
• Solitary Bone Cyst

This is a fairly long differential diagnosis. However, it is one that you must learn. I still run through it every time I see one of these lesions, just to make sure that I consider all of the important possibilities.

The discussion that follows will dwell almost totally on the plain radiographic findings of these lesions. CT and MRI are wonderful tools for tumor workups, but they are fairly non-specific. Their place in the workup is to tell us where the lesion is: what its extent is; whether there are any metastases (either in the same bone or elsewhere); and whether an adjacent joint, nerve or blood vessel is involved. However, to tell us what a lesion is, the plain radiograph is still supreme. We've been looking at the darned things for almost a century now, and the plain film findings of most bone tumors are fairly well known. Plain films are not terribly sensitive, but they do have a decent specificity. Therefore, any workup of a bone tumor should start with a good set of plain films.