Differential Diagnosis for Low Signal Marrow Lesion at the Medial Proximal Right Humerus
- Single Most Likely Diagnosis
- Metastasis: This is often the most common diagnosis for a focal low signal marrow lesion, especially in adults, due to the high prevalence of cancers that metastasize to bone, such as breast, lung, and prostate cancer. The location and description of the lesion are consistent with a metastatic deposit.
- Other Likely Diagnoses
- Osteonecrosis (avascular necrosis): Although less common in the humerus compared to other bones like the femur or humeral head, osteonecrosis can present as a low signal intensity lesion on MRI due to the replacement of normal marrow with necrotic bone and sometimes fibrotic tissue.
- Bone infarct: Similar to osteonecrosis, a bone infarct can appear as a low signal intensity lesion on T1-weighted images due to the ischemic changes within the bone marrow.
- Enchondroma: A benign cartilaginous tumor that can present as a well-defined low signal intensity lesion on T1-weighted images, especially if it contains calcifications or if the tumor matrix is dense.
- Do Not Miss Diagnoses
- Osteomyelitis: Although it might present differently, chronic osteomyelitis can sometimes appear as a low signal intensity lesion due to the presence of fibrosis and sclerosis. It's crucial not to miss this diagnosis due to its significant implications for treatment and patient outcome.
- Lymphoma: Bone involvement by lymphoma can manifest as a low signal intensity lesion on T1-weighted images. Given the potential for aggressive disease, missing this diagnosis could have significant consequences.
- Rare Diagnoses
- Chondrosarcoma: A malignant cartilaginous tumor that can present as a low signal intensity lesion on T1-weighted images, especially if it is of the low-grade type or contains significant calcification.
- Giant Cell Tumor: Typically presenting in the epiphyses of long bones, a giant cell tumor could potentially extend into the metaphysis and appear as a low signal intensity lesion, although this would be less common in the humerus.
- Intraosseous ganglion: A rare benign lesion that can mimic a cystic structure within the bone but might appear as a low signal intensity lesion on T1-weighted images if filled with a dense fibrous or myxoid material.