Rare Case Of Temporally Spontaneous Regression Of Retroperitoneal Paraganglioma

Abstract

We report a retroperitoneal paraganglioma that had spontaneously regressed, and recurrence 5 years later after CT scan diagnosis. The case involved a 64-year-old man. In the original complaint, the patient requested medical examination on experiencing sudden nausea accompanied by upper left abdominal pain. There was no apparent family history. A CT scan showed a left retroperitoneal tumor (Fig. 1a, left). The major axis of this tumor was 32 mm. However, follow-up CT imaging 4 and 8 months later showed spontaneous tumor regression (Fig. 1a, middle). We could detect a normal left adrenal gland, which was 18 mm. The physician followed him after the tumor regressed, because the patient was treated for his hypertension. The patient returned for examination approximately 5 years later with similarly-located severe left abdominal pain. Aside from a blood pressure of 150/100, there was no abnormal physical finding. Blood test results showed a white blood cell count of 101 × 102/μL (neutrophil: 90%, lymphocyte: 10%), but no other abnormal finding. A 24-h urine collection was carried out, yielding the following hormone levels: adrenaline 3417.1 µg/day; noradrenaline 1723.2 µg/day; dopamine 975.8 µg/day, metanephrine 10.08 mg/day, normetanephrine 2.64 mg/day and vanillylmandelic acid 48.72 mg/day. These results suggested a pheochromocytoma or paraganglioma. A follow-up abdominal CT scan showed a 62-mm left retroperitoneal tumor near the superior pole left kidney, adhering to the ventral aorta and pancreas (Fig. 1a, right). Magnetic resonance imaging signals showed a heterogenous tumor with T1 high and T2 low intensity. An MIBG scan showing a clustering of neoplastic lesions strongly suggested a pheochromocytoma or a paraganglioma. As imaging showed the tumor to be large with possible adhesion to surrounding tissue, left adrenal gland and tumor resection was carried out. The subsequent pathological diagnosis was paraganglioma of the retroperitoneum. Microscopically, the tumor was located in the retroperitoneal suprarenal region without adrenal invasion (Fig. 1b). The well-capsulated tumor made characteristic clear cell nests with a so-called Zellballen pattern, and each cuboidal cell showed abundant acidophilic granulates within the cytoplasm (Fig. 1b). Necrosis or mitoses were very few. Patients with pheochromocytomas and sympathetic paragangliomas often experience a hyperproduction of catecholamines, showing reactions such as extreme palpitations, excessive perspiration and weight loss. However, as symptoms manifest intermittently in response to stress, they are occasionally overlooked. Parasympathetic paraganglioma, meanwhile, are characterized by large tumors and minor clinical symptoms that are often overlooked if they do not include intracranial pressure.1 The tumor in our current case manifested at the same site as another tumor some 5 years earlier, strongly suggesting recurrence of a paraganglioma. We considered these three possible explanations for the disappearance of our patient's neoplastic lesion: (i) shrinkage as a result of hemorrhagic transformation and physiological absorption; (ii) tumor rupture; and (iii) spontaneous regression. Imaging and pathological data showed the tumor to be hypovascular with no acute hemorrhaging. Our search of the literature found only one case report of spontaneous regression of untreated retroperitoneal paraganglioma.2 Furthermore, although there are occasional case reports of ruptured pheochromocytomas, we found one report of the rupture of a paraganglioma.3, 4 None declared.