A 38 year old woman presents with nonproductive couch over the past month.
After a right lung nodule was seen on chest radiograph, the patient then underwent contrast-enhanced chest CT:
A pleural-based nodule in the right upper lobe is noted, and evaluation on soft tissue windows reveals no evidence of internal fat or calcification.
The patient underwent further evaluation with PET/CT, which demonstrated minimal FDG activity in the nodule, less than that of mediastinal blood pool.
This patient was diagnosed with a solitary fibrous tumor. This uncommon mesenchymal fibroblastic neoplasm (in the same family as hemangiopericytoma) usually has an indolent course, but a minority of lesions have been described to recur after resection or metastasize.
Most patients present with nonspecific complaints (such as persistent cough in this case), but this tumor is notable for several potential paraneoplastic syndromes. Less than 5% of cases may present with refractory hypoglycemia, due to secretion of insulin-like growth factor II by larger tumors. Up to 20% of cases may be associated with hypertrophic pulmonary osteoarthropathy (see Musculoskeletal Case 5 – coming soon).
Although few studies have been reported regarding use of FDG PET/CT in this uncommon tumor, published data has shown low levels of FDG uptake in most tumors with more intense FDG uptake described in more aggressive/malignant lesions. Compare the FDG uptake in this patient’s tumor to this different patient with a more locally invasive mass, diagnosed as malignant mesothelioma:
References:
Boddaert G, et al. Ann Thorac Surg 2015;99:1025-31.
Yeom YK, et al. Medicine (Baltimore) 2015;94:e1548.
Tazeler Z, et al. Rev Esp Med Nucl Imagen Mol 2016;35:165-70.