Final diagnosis of subjects with positive and negative PET/CT results for indicating the primary cancer.

<p>Final diagnosis of subjects with positive and negative PET/CT results for indicating the primary cancer.</p

Role of ¹⁸F-FDG PET/CT in patients without known primary malignancy with skeletal lesions suspicious for cancer metastasis

<div><p>Background</p><p>When subjects without a known malignancy present with suspicious skeletal lesions, differential diagnosis and primary cancer identification is important. Here, we investigated the role of FDG PET/CT in this clinical situation.</p><p>Methods</p><p>We enrolled 103 patients with no known malignancies who were referred for FDG PET/CT because of bone lesions that were suspicious for cancer metastasis. Each extra-skeletal FDG lesion was categorized as consistent with primary cancer or with metastasis based on the distribution and pattern of all abnormal lesions in the individual.</p><p>Results</p><p>Final diagnosis revealed that bone lesions represented cancer metastasis in 75 patients (72.8%). In the remaining 28 patients (27.2%), they were from other causes including multiple myeloma or lymphoma, malignant primary bone tumor, and benign bone disease. PET/CT indicated a primary cancer in 70 patients (68.0%). This was the correct primary site in 46 cases and the incorrect site in 13 cases (including 6 cases with cancer of unknown primary, CUP). In the remaining 11 cases, the bone lesions were due to other causes. PET/CT did not indicate a primary cancer in 33 patients (32.0%). Of these cases, 17 did not have a primary cancer, 8 had CUP, and 8 had primary cancers that were missed. Thus, PET/CT had a sensitivity of 61.3% and specificity of 60.7% for primary cancer identification in the entire population. Excluding patients with CUP, PET/CT sensitivity was 75.4%. PET/CT also provided information useful for recognizing multiple myeloma and benign bone disease as the cause of the skeletal lesions.</p><p>Conclusions</p><p>In patients without known malignancies with suspected skeletal cancer metastasis, FDG PET/CT can help identify the primary cancer and provide useful information for differential diagnosis.</p></div

Final diagnosis of patients that were PET/CT negative for primary cancer.

<p>Final diagnosis of patients that were PET/CT negative for primary cancer.</p

A 55-year-old male with gastric cancer identified by FDG PET/CT.

<p>(a) The maximum intensity projection image shows multiple hypermetabolic metastatic lesions in the skeleton, liver and hepatoduodenal lymph nodes. (b) A FDG lesion was detected in the stomach that was interpreted as primary gastric cancer (arrow). Endoscopy revealed a 3-cm-sized ulcerative gastric mass and biopsy confirmed adenocarcinoma of the stomach.</p

PET/CT features indicating multiple myeloma as cause for bone lesions.

<p>PET/CT features indicating multiple myeloma as cause for bone lesions.</p