[Clinicopathological features of composite pheochromocytoma]

Objective: To detect the clinicopathological features, immunophenotype, diagnosis, and differential diagnosis of composite pheochromocytoma(CP). Methods: Five cases of CP were collected at Zhejiang Provincial People's Hospital from January 2011 to January 2019. The clinical, radiological, histologic, immunohistochemical and outcome data were analyzed; the diagnosis and differential diagnosis were discussed. Results: The patients' age range was 52-68 years (mean 59 years, median 54 years), There were 4 males and 1 female, and the male to female ratio was 4∶1. Tumor size was 3-4 cm (mean 3.6 cm, median 3.5 cm). The most common clinical manifestation was adrenal mass. Histologically, the classical feature was two distinct morphologic components, one with tumor cells arranged in irregular nests, and with fine granular and basophilic oramphophilic cytoplasm; the other was composed of scattered ganglion cells in the background of Schwann cells organized in interwoven bundles. The components of pheochromocytoma expressed PHOX2B(5/5), synaptophysin (5/5), CgA (5/5), the sustentacular cells expressed S-100 protein; the components of ganglioneuroma expressed S-100 protein (5/5), NF (5/5), the ganglion cells were weakly positive for PHOX2B, synaptophysin and CgA. All the cases were surgically resected and all patients were free of recurrence at follow-up. Conclusions: CP is rare adrenal tumor, and it has typical histologic features but no specific clinical manifestations. Attention should be paid to its characteristic histomorphology with the use of PHOX2B, CgA, synaptophysin and S-100 protein immunohistochemistry that is helpful for its diagnosis.