Clinical, Diagnostic, and Treatment Characteristics of SDHA-Related Metastatic Pheochromocytoma and Paraganglioma

Background: Pheochromocytoma and paraganglioma (PHEO/PGL) are rare neuroendocrine tumors which may cause potentially life-threatening complications, with about a third of cases found to harbor specific gene mutations. Thus, early diagnosis, treatment, and meticulous monitoring are of utmost importance. Because of low incidence of succinate dehydrogenase complex subunit A (SDHA)-related metastatic PHEO/PGL, currently there exists insufficient clinical information, especially with regards to its diagnostic and treatment characteristics.Methods: Ten patients with SDHA-related metastatic PHEO/PGL were followed-up prospectively and/or retrospectively between January 2010–July 2018. They underwent biochemical tests (n = 10), 123I-MIBG (n = 9) scintigraphy, and multiple whole-body positron emission tomography/computed tomography (PET/CT) scans with 68Ga-DOTATATE (n = 10), 18F-FDG (n = 10), and 18F-FDOPA (n = 6).Results: Our findings suggest that these tumors can occur early and at extra-adrenal locations, behave aggressively, and have a tendency to develop metastatic disease within a short period of time. None of our patients had a family history of PHEO/PGL, making them appear sporadic. Nine out of 10 patients showed abnormal PHEO/PGL-specific biochemical markers with predominantly noradrenergic and/or dopaminergic phenotype, suggesting their utility in diagnosing and monitoring the disease. Per patient detection rates of 68Ga-DOTATATE (n = 10/10), 18F-FDG (n = 10/10), 18F-FDOPA (n = 5/6) PET/CT, and 123I-MIBG (n = 7/9) scintigraphy were 100, 100, 83.33, and 77.77%, respectively. Five out of 7 123I-MIBG positive patients had minimal 123I-MIBG avidity or detected very few lesions compared to widespread metastatic disease on 18F-FDG PET/CT, implying that diagnosis and treatment with 123/131I-MIBG is not a good option. 68Ga-DOTATATE PET/CT was found to be superior or equal to 18F-FDG PET/CT in 7 out of 10 patients and hence, is recommended for evaluation and follow-up of these patients. All 7 out of 7 patients who received conventional therapies (chemotherapy, somatostatin analog therapy, radiation therapy, 131I-MIBG, peptide receptor radionuclide therapy) in addition to surgery showed disease progression.Conclusion: In our cohort of patients, SDHA-related metastatic PHEO/PGL followed a disease-course similar to that of SDHB-related metastatic PHEO/PGL, showing highly aggressive behavior, similar imaging and biochemical phenotypes, and suboptimal response to conventional therapies. Therefore, we recommend careful surveillance of the affected patients and a search for effective therapies

111In-Pentetreotide Scintigraphy Versus 68Ga-DOTATATE PET: Impact on Krenning Scores and Effect of Tumor Burden.

Eligibility for somatostatin receptor (SSTR) radionuclide therapy uses the qualitative Krenning score based on 111In-pentetreotide planar scintigraphy as was performed in the NETTER-1 trial. The purpose of this study was to determine the effect of using SSTR PET-based Krenning score in comparison to 111In-pentetreotide. Methods: This was a post hoc head-to-head comparison of 68Ga-DOTATATE-based and 111In-pentetreotide-based Krenning scores in 150 patients included in a prospective phase 2 study (NCT01967537). Patients were imaged using 68Ga-DOTATATE PET/CT, 111In-pentetreotide planar scintigraphy, and SPECT/CT within 1 wk. SSTR ligand uptake was graded using the Krenning score independently by 3 readers. Results: The detection rate of SSTR-expressing disease (Krenning scores 2-4) was 23%, 38%, and 72% with planar imaging, SPECT, and SSTR PET, respectively. The Krenning score was higher with SSTR PET (2.71 ± 1.74) than with planar imaging (0.75 ± 1.37; P < 0.001) or SPECT (1.23 ± 1.57; P < 0.001). In patients with a Krenning score of at least 3 on SSTR PET, the detection rate of planar imaging and SPECT was lower for lesions smaller than 2 cm than lesions 2 cm or larger: 15% and 24% versus 78% and 89%, respectively (P < 0.001). For lesions larger than 5 cm, Krenning scores between SSTR PET and 111In-pentetreotide were nearly equivalent. Lesion size did not have an impact on SSTR PET Krenning scores. Interreader agreement was higher for SSTR PET than for planar imaging or SPECT (0.79 vs. 0.67 and 0.50, respectively). Conclusion: SSTR PET results in higher Krenning scores than 111In-pentetreotide, particularly when lesions measured 2 cm or less. Small lesion size resulted in low Krenning scores using 111In-pentetreotide, but lesion size did not affect SSTR PET-based Krenning scores. The results of the NETTER-1 trial cannot be directly applied to patients with small lesions. Further study of peptide receptor radionuclide therapy in patients with small lesions negative on 111In-pentetreotide imaging and positive on SSTR PET is warranted

18F-Naf And 18F-Fdg Pet/Ct In Gorham-Stout Disease

Gorham-Stout disease (GSD) is an extremely rare skeletal disorder of unknown etiology characterized by benign proliferation of vascular or lymphatic channels, leading to progressive bone resorption. We report on a patient diagnosed with GSD affecting the right scapula and the right ribs, who underwent PET/CT scans using F-FDG and F-NaF. The remnant upper portion of the affected scapula did not show F-FDG uptake but demonstrated markedly increased F-NaF activity. Furthermore, intense F-NaF activity was seen on the right posterior ribs, which were actively being resorbed, suggesting the potential application of F-NaF-PET/CT imaging in GSD diagnosis and follow-up

\u3csup\u3e18\u3c/sup\u3eF-Naf Pet/Ct In Extensive Melorheostosis Of The Axial And Appendicular Skeleton With Soft-Tissue Involvement

Melorheostosis is a rare, nonhereditary, benign, sclerotic bone dysplasia with no sex predilection, typically occurring in late childhood or early adulthood, which can lead to substantial functional morbidity, depending on the sites of involvement. We report on a patient with extensive melorheostosis in the axial and appendicular skeleton, as well as in the soft tissues, who was evaluated with whole-body 18F-NaF PET/CT scan. All melorheostotic lesions of the skeleton and of the ossified soft-tissue masses demonstrated intensely increased 18F-NaF activity, suggesting the application of this modality in assessing and monitoring the disease activity

Avascular Necrosis Of The Hips With Increased Activity On 68Ga-Dotatate Pet/Ct

Prolonged exposure to cortisol is one of the major causes of avascular bone necrosis (AVN). We report on a case of a woman with Cushing syndrome attributed to ectopic adrenocorticotropic hormone-secreting tumor who was evaluated with whole-body PET/CT study using Ga-DOTATATE. The scan showed increased activity by both femoral heads, corresponding to the margins of bilateral AVN seen on MRI. The presented data suggests AVN-induced reactive inflammatory alterations adjacent to the necrotic segment of the bone, which can be effectively targeted using radiolabeled somatostatin (SST) analogs

Epididymal Cystadenomas In Von Hippel-Lindau Disease Showing Increased Activity On \u3csup\u3e68\u3c/sup\u3eGa Dotatate Pet/Ct

von Hippel-Lindau (VHL) disease is a familial cancer syndrome characterized by the development of a variety of malignant and benign tumors, including epididymal cystadenomas. We report a case of a VHL patient with bilateral epididymal cystadenomas who was evaluated with 68Ga DOTATATE PET/CT, showing intensely increased activity (SUVmax, 21.6) associated with the epididymal cystadenomas, indicating cell-surface overexpression of somatostatin receptors. The presented case supports the usefulness of somatostatin receptor imaging using 68Ga DOTA-conjugated peptides for detection and follow-up of VHL manifestations, as well as surveillance of asymptomatic gene carriers

Schmorl Nodes Can Cause Increased \u3csup\u3e68\u3c/sup\u3eGa Dotatate Activity On Pet/Ct, Mimicking Metastasis In Patients With Neuroendocrine Malignancy

Schmorl node (SN) is the herniation of the nucleus pulposus through the cartilaginous and bony endplate into the adjacent vertebral body. It is documented that SNs produce areas of moderately increased 18F-FDG uptake.We present a case of a patient with history of neuroendocrine tumor, who underwent 68Ga DOTATATE PET/CT for follow-up, showing increased focal vertebral uptake suggestive of bone metastasis. CT revealed typical findings of an SN. The presented case indicates that SNs should be considered when encountering focally increased skeletal uptake in 68Ga DOTATATE PET/CT studies, which can mimic metastasis in patients with history of neuroendocrine tumors