Clinical Characteristics and Diagnostic Pitfalls of Pheochromocytoma: A Pathology-Confirmed Retrospective Study From a Single Japanese Center

Objective: Pheochromocytoma poses diagnostic challenges, especially in small or atypical tumors. Despite the use of various imaging modalities, their preoperative diagnostic accuracy remains limited. The study aimed to assess pathologically confirmed cases of pheochromocytoma and clarify diagnostic pitfalls and various imaging findings. Patients and methods: We retrospectively analyzed 47 pathologically confirmed pheochromocytomas treated at our institution between 2015 and 2022. Clinical characteristics, biochemical results, and imaging findings [computed tomography (CT), magnetic resonance imaging (MRI), and 123I-metaiodobenzylguanidine (MIBG) scintigraphy] were reviewed. MRI scans were independently reviewed by two board-certified radiologists, with consensus on discrepancies. Results: The mean patient age was 59.3 years, and the mean tumor size was 4.26 cm. The 123I-MIBG scintigraphy positivity rate was 85.1%. Characteristic MRI features, including high signal intensity on T2-weighted images, internal heterogeneity, early enhancement, and lack of signal drop on fat-suppressed T2 images, were observed in >90% of cases. No adverse events occurred among 31 patients who underwent contrast-enhanced CT without α-blocker pretreatment. Three tumors were non-functional and 123I-MIBG-negative, diagnosed only via postoperative pathology. Conclusion: Diagnosing pheochromocytoma remains challenging in small or atypical cases, emphasizing the value of combining multiple imaging modalities, particularly MRI. These findings highlight the importance of a multimodal approach in clinical practice.