Metastatic Poorly Differentiated Prostatic Carcinoma With Neuroendocrine Differentiation

Abstract

Glu-NH-CO-NH-Lys-(Ahx)-[Ga-68(HBED-CC)], abbreviated as Ga-PSMA, is a novel radiotracer undergoing evaluation for PET/CT imaging of prostate carcinoma. Its major advantage is the sensitive detection of lesions even at low prostate-specific antigen level and high target-to-background ratios obtained in metastatic lesions, which is better than that obtained with F-fluoromethylcholine. We present the case of a 28-year-old man with poorly differentiated prostate carcinoma with neuroendocrine differentiation, whose lesions did not show significant Ga-PSMA localization. As literature on utility of Ga-PSMA PET/CT for imaging prostate carcinoma grows, it is important to be aware of potential false negatives that could influence study results.

Unusual Uptake of Prostate Specific Tracer 68Ga-PSMA–HBED-CC in a Benign Thyroid Nodule

“…Enhanced PSMA expression is seen in poorly differentiated, metastatic, and hormone refractory cancers [5,6]. The major advantage of this tracer is that it is a very sensitive modality for the detection of recurrent lesions and gives a high target-to-background ratio in metastatic sites even at low levels of PSA [7]. The most useful role of this tracer has been in cases of biochemical recurrence [8].…”

“…An early study by Chang et al showed that anti-PSMA monoclonal antibodies react strongly with neovasculature of various tumors including clear renal cell carcinoma, transitional cell carcinoma of the urinary bladder, testicular embryonal carcinoma, colonic adenocarcinoma, neuroendocrine carcinoma, glioblastoma multiforme, malignant melanoma, pancreatic duct carcinoma, non-small cell lung carcinoma, soft tissue sarcoma, breast carcinoma, and prostatic adenocarcinoma [15]. Another early study also reported PSMA immunoreactivity in cells of the duodenal mucosa, renal tubules, neuroendocrine cells in the colonic crypts, apart from a few malignancies like renal cell carcinoma and colonic adenocarcinomas [7]. To the best of our knowledge, this is the first case in literature where 68 Ga-PSMA-HBED-CC uptake has been demonstrated in a follicular adenoma of the thyroid.…”

Nuclear Medicine Imaging of Prostate Cancer

“…The authors recorded a dependence of lymph node metastasis detection in Ga-68-PSMA PET/CT on size and are the only workgroup to date to subsequently classify the diagnostic accuracy of Ga-68-PSMA PET/CT in the case of lymphogenous metastasis as reduced [68]. In a case report, Chakraborthy et al published a Ga-68-PSMA PET/CT examination with false-negative results in poorly differentiated PCa with neuroendocrine differentiation [69]: A clinical situation in which the diagnostic value of Ga-68-PSMA PET/CT may be low [69]. in which the authors were able to show that Ga-68-labeled PSMA can also be used for MR-PET diagnostic imaging as an interesting tracer with the possibility for simple and accurate detection [64,65].…”

PSMA PET in Prostate Cancer

“…False-negative results may include prostate tumors with neuroendocrine differentiation, small tumors, and tumors located next to areas with high physiologic tracer uptake (7). False-positive results have been reported with physiologic uptake in the celiac ganglia (8).…”