Misdiagnosis and analysis of clinical characteristics in patients with giant cystic pheochromocytoma/paraganglioma

Introduction: Although giant cystic pheochromocytoma and paraganglioma (PPGL) are uncommon, they can be life-threatening when it occurs. Unfortunately, prior case reports have shown that giant cystic PPGLs are highly susceptible to diagnostic errors. Therefore, this study aimed to explore giant cystic PPGLs by comparing them with non-cystic PPGLs, defining the clinical features of the affected patients, and analyzing the characteristics of misdiagnosis and mistreatment associated with PPGLs. The goal is to provide insights for the timely and accurate diagnosis and treatment of giant cystic PPGLs.

Methods: A total of 170 cases of pheochromocytoma and paraganglioma (PPGL) diagnosed at the First Affiliated Hospital of Chongqing Medical University from April 2011 to April 2020 were confirmed through clinical evaluation, measurement of catecholamine metabolites, imaging studies, or surgical pathology. The patients were classified into two groups based on the maximum tumor diameter and the presence of cystic components. The clinical characteristics of patients in the giant cystic group, including timely diagnosis and instances of misdiagnosis, are summarized. Additionally, the differences in demographics, clinical manifestations, laboratory examinations, imaging features, treatment approaches, and tumor characteristics between the two groups were analyzed.

Results: Among the 17 patients in the giant cystic group, eight (47.1%) patients were misdiagnosed. The misdiagnosis and mistreatment characteristics of PPGLs were as follows: female (50%); median age, 51 years; normal blood pressure; greater mass effect at onset; larger tumors; median time to diagnosis extension, 180 days; and misdiagnosed disease, which was mainly tumors of adjacent organs, the digestive system, the cardiovascular system, the urinary system, the nervous system, or the endocrine system. The giant cystic group had greater mass effects than did the non-cystic group (P < 0.05). The proportion of patients with the triad of pheochromocytoma (heart palpitations, sweating and headache) and hypertension was lower; however, this difference was not statistically significant. The blood MN (metanephrine) level was greater, and the hemoglobin and blood low-density lipoprotein cholesterol (LDL-cholesterol) levels were lower (P < 0.05). The proportions of patients with tumor calcification and hemorrhagic necrosis were significantly greater (P < 0.05). There was more intraoperative bleeding, more patients who underwent blood transfusions, and a longer postoperative hospital stay; however, the difference was not statistically significant.

Conclusion: Giant cystic pheochromocytomas and paragangliomas (PPGLs) are rare, and their clinical manifestations are atypical. Additionally, imaging findings can be challenging to identify due to the presence of large space-occupying adjacent organs. As a result, these giant cystic lesions of unknown origin are often misdiagnosed. Early biochemical examination, in conjunction with imaging characteristics, is essential to accurately determine the nature of the tumor and reduce the rate of misdiagnosis.