A 57 year old woman presents with right knee pain and hoarseness.
1. FDG avid left upper lobe primary lung cancer with left mediastinal metastasis.
2. Asymmetrical laryngeal activity with markedly reduced left side activity due to mediastinal left recurrent laryngeal impingement.
3. FDG avid left adrenal metastasis.
4. FDG avid right lateral condyle subchondral fracture with correlative MRI demonstrating subchondral low signal on proton density MR and high signal on fat suppressed T2 MR.
Spotlights March 2015 Case
1. Lung cancer (D) is the best choice to explain the PET findings. Adrenal cancer (A) is possible, but primary adrenal malignancies are much less common than lung cancer metastases to the adrenal. Laryngeal cancer (B) can certainly demonstrate asymmetrical FDG activity, but in this case, the reduced activity left cord is abnormal likely due to left recurrent nerve effacement by the large left mass adjacent to the mediastinum. The right pelvic annular activity could be a colon cancer (D) or precancerous lesion, but large lung and adrenal metastases associated with such a small primary would not be expected. Osteosarcoma (E) is typically a metaphyseal lesion, not epiphyseal. Osteosarcoma without an underlying condition such as Paget or prior radiation is extremely unlikely in a 57 year old patient.
2. Fracture (A) is the best diagnosis based on location (anterior distal femoral epiphysis) and subchondral lenticular configuration with edema and cortical fracture with marrow extrusion by MRI (lower row images). Bones appear to be osteoporotic by radiography. Although lung cancer may metastasize to distal extremities, neoplasm or infection is very unlikely in the distal femoral epiphysis. Incidentally, there is mild FDG activity in the suprapatellar bursa.
1. Chest findings are typical for lung cancer. Metastases and tuberculosis or sarcoidosis might present with similar images.
2. Laryngeal findings are typical for left recurrent laryngeal nerve impingement. Right sided laryngeal cancer is an unlikely remote possibility
3. Left adrenal metastasis is most likely; Less likely primary adrenal lesions are much less likely considerations.
4. Based on the PET, CT, and MRI, subchondral lateral condyle fracture is by far the best diagnosis.
1. Lung cancer primary lesions and metastases are typically FDG avid.
2. Laryngeal asymmetry may be associated with tumor (avid) , or denervation (reduced activity).
3. Fractures may be rather FDG avid.
4. Adrenal metastasis are commonly FDG avid.
Mettler FA, Guiberteau MJ. Essentials of nuclear medicine imaging. Philadelphia, PA : Elsevier/Saunders, ©2012. Chapter 11.