Table 1: Differential diagnosis of a well-defined lytic lesion of the rib (based on [3, 9, 12, 13]).

Tumor namePatient ageRib locationImaging pattern

Benign

Fibrous dysplasia (monostotic)Most patients: 20–30 years oldCommonMay cause cortical thickening and exhibit amorphous calcification or ground glass appearance.
Enchondroma2nd–5th decade of lifeCommonExpansile lytic lesion, which may have calcified cartilaginous matrix. Usually located at the costochondral or costovertebral junction.
Eosinophilic granulomaMost cases seen before the age of 30CommonSolitary lytic lesion. A sclerotic margin may be present in the healing phase.
Brown tumorDepends on the age of development of hyperparathyroidismRareMay be identical to GCT on imaging and histology. Laboratory tests should confirm hyperparathyroidism.
Aneurysmal bone cyst Most cases seen before the age of 30RareExpansile lesion which may exhibit bone destruction and extension into adjacent soft tissue. Fluid-fluid levels commoner than in GCT.
Simple bone cystMost cases seen before 20 yrsRareOvoid lytic lesion, often with a fine sclerotic margin.
Chondromyxoid fibromaLess than 30 yrsRare
Well-marginated masses with scalloped sclerotic borders. No internal calcification. Possible cortical expansion.

Malignant

MetastasisCommoner after 50 yrsCommonWell- or ill-defined osteolysis without sclerotic rim. Most common primaries: lung and breast.
Solitary myelomaMean age: 50 yrsCommonWell-defined, “punched out” lytic lesion, which may cause expansion. No sclerotic margin.
Chondrosarcoma (low grade)Most cases seen after 50 yrs CommonBetter differentiated tumors are well defined. Arc-like, stippled, or amorphous calcification is common.