Functional paragangliomas are easily discovered because of the symptoms caused by excessive secretion of catecholamines and their metabolites, such as paroxysmal or persistent hypertension, hyperhidrosis, palpitations, and headache. Non-functional paraganglioma are typically detected when they cause symptoms of local compression. For example, patients with retroperitoneal or abdominal aortic paraganglioma often develop abdominal pain, abdominal discomfort, and back pain. Pelvic paragangliomas often cause urinary frequency and painless hematuria. Gastrointestinal paragangliomas may cause nausea, vomiting, constipation, and intestinal obstruction. In some patients, paragangliomas may be incidentally discovered during routine health examination. In this case, the patient developed symptoms of heart failure, and paraganglioma was discovered on ultrasound examination.
The diagnosis of extra-adrenal paraganglioma includes qualitative diagnosis and locational diagnosis. Determination of catecholamine levels (norepinephrine, epinephrine, dopamine) and their intermediate metabolites (metanephrine, methoxytryramine) and terminal metabolites (e.g. vanilmandelic acid) is an important basis for the qualitative diagnosis of paraganglioma [5, 6]. The sensitivity and specificity of measurement of catecholamines and their intermediate and terminal metabolites in plasma or urine for the qualitative diagnosis of paraganglioma are different. Among them, metanephrine and methoxytryramine have higher specificity and sensitivity [5, 7]. The levels of epinephrine and norepinephrine in this disease could be normal. Vanilmandelic acid is the final metabolite of epinephrine and norepinephrine, and its elevation is also significant for the diagnosis of disease [3, 5]. In this case, 24-h urinary vanilmandelic acid was elevated and adrenaline was normal, which is consistent with the characteristics of the disease. Pathological examination of non-functional tumors is necessary to prevent misdiagnosis.
Ultrasound, computed tomography, magnetic resonance imaging, 123I-MIBG and PET-CT are invaluable in locational diagnosis of paraganglionoma. In particular, 123I-MIBG has the highest specificity (95–100%) because it is an epinephrine analogue and can be absorbed by pheochromocyte catecholamine vesicles [8]. In this case, the lesion was detected on pelvic ultrasound. Subsequently, pelvic enhanced CT and ultrasound-guided transrectal pelvic mass puncture was performed to obtain the final pathological diagnosis.
In a case of rectal paraganglioma reported by Yu et al. [1], the tumor was composed of nested pleomorphic cells surrounded by bifurcated and fine blood vessels, forming characteristic Zellballen. Pleomorphic cells had abundant eosinophilic and amphiphilic granular cytoplasm, round or ovoid nuclei, and prominent nucleoli. There was tumor necrosis and vascular infiltration. On immunohistochemistry, the pleomorphic cells showed strong expression of pheochromogranin, synaptophysin, CD56, NSE, and vimentin [1]. The pathological results of this case were consistent with the pathological characteristics of most paragangliomas: nest-like distribution of cell masses, abundant pink or dichromatic cytoplasm, slightly enlarged nuclei, and rare mitoses. Studies have shown that most paragangliomas are S100 positive, synaptophysin (+), pheochromogranin(+), vimentin(+), and AE1 + AE3 negative. The immunohistochemical characteristics of this case were CgA(+), SyN(+), S-100(+), Cata-3(+), Ki-67(approximately 10% +), and Inhibin-A (+). SMA, CD117, DOG, HMB45, TTF-1, CaM5.2, Melana, AE1/AE3, WT1, D2-40, p63, and calretinin were all negative, which are also in accordance with the typical immunohistochemical results.
In 2017, the WHO proposed the term “metastatic paraganglioma” instead of “malignant paraganglioma”. The 2014 Endocrine Society clinical practice guidelines for pheochromocytoma and paraganglioma suggest that 10–17% of pheochromocytomas and paragangliomas are malignant, of which the proportion of paragangliomas is higher [5]. Malignant extra-adrenal paraganglioma is rare and reported to be less than 3%, of which nearly 75% are sporadic and 25% are hereditary [9]. Malignant tumors are mostly metastases or spread to organs without chromaffin tissue [10].
Paragangliomas are also categorized as benign and malignant. The distinction between benign and malignant is different from that in other tumors, and it does not depend on pathological diagnosis. At present, the diagnosis of malignant paraganglioma mainly depends on the presence or absence of intravascular tumor thrombus, local invasion, or lymph node metastasis. A study showed that histopathological findings of abundant intratumoral necrosis, vascular invasion, cystic invasion, and strong mitotic activity suggest the possibility of malignancy [11]. Some studies have also shown that the criteria for malignancy are tumor metastasis and tumor proliferation in non-chromaffin tissues. Factors associated with malignancy were large tumor size (> 5 cm), obvious nuclear pleomorphism, increased mitotic activity, tumor necrosis, lack of supporting cells, vascular invasion, diffuse surrounding structures and tissues, and high Ki67 index [3]. The grade of pheochromocytoma and paraganglioma, known as the GAPP score, is based on tumor pathology, cellular properties, acne-like necrosis, vascular or cystic infiltration, Ki67 index, and type of catecholamine secretion, with a maximum score of 10. A score of 0–2 indicates highly differentiated, 3–6 indicates moderately differentiated, and 7–10 indicates poorly differentiated. The 5-year survival rate was 100% for highly differentiated patients, 66.8% for moderately differentiated patients, and 22.4% for poorly differentiated patients [1]. Studies have shown that GAPP score is associated with survival or metastatic rates of paraganglioma [12].
This case was malignant paraganglioma, which was considered metastatic based on multiple retroperitoneal enlarged nodules (approximately 59 × 34 mm in diameter) detected on abdominal and pelvis enhanced CT. Bone ECT showed multiple spots, slices and strips of nuclide enhancement in the skull, vertebra, bilateral ribs, bilateral scapula, left upper humerus, pelvic bone, and right upper femur. These findings were suggestive of bone metastases.
Surgery is still the main treatment modality. Hypertension should be adequately controlled before surgery to prevent intraoperative hypertensive crisis or arrhythmia. Hemalatha reported a patient with retroperitoneal paraganglioma who died during the surgery because of hypertensive crisis [13]. Radiotherapy and chemotherapy can be used for patients with metastases. I-MIBG is ingested by pheochromocyte vesicles, leading to emission of β rays, which can act on pheochromocytes to achieve therapeutic effect. This patient disapproved of chemotherapy for personal reasons, and died within six months of diagnosis.
The possibility of neuroendocrine-related tumors, for example paragangliomas, should be considered in young patients with heart failure, especially those with concomitant hypertension and diabetes. Better characterization of the disease can facilitate early diagnosis and help improve treatment outcomes.