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),
123
I-MIBG (
n
= 9) scintigraphy, and multiple whole-body positron emission tomography/computed tomography (PET/CT) scans with
68
Ga-DOTATATE (
n
= 10),
18
F-FDG (
n
= 10), and
18
F-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
68
Ga-DOTATATE (
n
= 10/10),
18
F-FDG (
n
= 10/10),
18
F-FDOPA (
n
= 5/6) PET/CT, and
123
I-MIBG (
n
= 7/9) scintigraphy were 100, 100, 83.33, and 77.77%, respectively. Five out of 7
123
I-MIBG positive patients had minimal
123
I-MIBG avidity or detected very few lesions compared to widespread metastatic disease on
18
F-FDG PET/CT, implying that diagnosis and treatment with
123/131
I-MIBG is not a good option.
68
Ga-DOTATATE PET/CT was found to be superior or equal to
18
F-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,
131
I-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 diseas...