FDG PET/CT imaging suggests lymphoma involving prostate may be more resistant to treatment. Clin Nucl Med. 2011;36:255-257. [PMID: 21285695 DOI: 10.1097/rlu.0b013e3181f9e012]

Malignant nonepithelial prostate tumors: FDG PET/CT findings with MRI and CT correlation

PURPOSE

The aim of this study was to evaluate F-FDG PET/CT findings of malignant nonepithelial prostate tumors and their correlation with MRI and CT images.

PATIENTS AND METHODS

FDG PET/CT findings were reviewed in 12 patients with malignant nonepithelial prostate tumor confirmed by pathology. The location, size, SUVmax, pathologic findings, and available MRI and CT images of the tumors were reviewed.

RESULTS

Of the 12 patients (mean age, 41 years; age range, 19-66 years), 9 had normal prostate-specific antigen levels. The mean size of the tumors was 7.1 cm in diameter ranging from 4.6 to 10.5 cm. All the tumors showed increased metabolic activity with mean SUVmax of 17.5 ranging from 3.6 to 46.8. The high-grade malignant tumors tended to show higher FDG uptake, whereas the intermediate-grade and low-grade malignant ones tended to show lower FDG uptake. Seven tumors had local invasion or distant metastases. Lung was the most common metastatic site. On MRI, the tumors showed well-circumscribed or ill-circumscribed margins with inhomogeneous enhancement. On CT, the tumors showed hypodensity with slight to moderate enhancement.

CONCLUSIONS

The malignant nonepithelial prostate tumors tended to have large sizes at presentation, have high FDG uptake, and affect a younger population with normal prostate-specific antigen levels. FDG PET/CT may be useful for the assessment of tumor grade and for detecting the distant metastases, whereas the MRI or enhanced CT may be more helpful for describing the relationship between the tumor and adjacent structures.

Positron emission tomography/computerized tomography in the evaluation of primary non-Hodgkin’s lymphoma of prostate

Primary malignant lymphoma of the prostate is exceedingly rare. Here we report a case of a 65-year-old man who presented with increased urinary frequency, urinary urgency, and urinary incontinence for two years. Benign prostatic hypertrophy was suspected at primary impression. Ultrasound revealed a hypoechoic lesion of the prostate. The total serum prostate-specific antigen was within normal range. Positron emission tomography/computerized tomography (PET/CT) showed a hypermetabolic prostatic lesion. Prostate biopsy was consistent with a non-germinal center diffuse large B cell lymphoma. There was complete remission of the prostatic lesion following six cycles of chemotherapy as shown on the second PET/CT imaging. ¹⁸F-fluoro-deoxy glucose PET/CT is not only a complement to conventional imaging, but also plays a significant role in the diagnosis and evaluation of treatment response of prostatic lymphoma.