Objective: To study the clinicopathological features and differential diagnosis of metanephric adenoma (MA).
Methods: The clinicopathological data of 16 cases with MA diagnosed and treated in Peking University First Hospital from 2004 to 2016 were retrospectively analyzed, and the clinical characteristics, pathologic parameters, differential diagnosis, treatment options and prognosis of MA were analyzed with literature review.
Results: The patients included 10 females and 6 males. The age of patients ranged from 14 to 83 years (mean=33.7 years). The partial nephrectomy was carried out for most patients. All cases were located in renal codex with 3 growing into the renal sinus. Histologically, the tumor was composed of tubules, papillary or glomeruloid structures and psammoma bodies were focally seen. Immunohistochemical study showed that all the cases expressed vimentin, and 94% cases expressed CD57, 63% WT1, 75% AE1/AE3, 19% cytokeratin 7 (CK7) and 13%α-methylacyl-CoA racemase (AMACR), and negative expressions for MA included CD10, neuron-specific enolase (NSE) and CD56. Follow-up information from 1 to 125 months was available in all the patients; and none of the patients showed any evidence of recurrence and metastasis.
Conclusion: The benign tumor characteristics of MA are not obvious for preoperative imaging diagnosis, and the diagnosis of MA should be based on the unique pathological features. Positive immunostain of CD57 is a useful indicator for MA diagnosis and differential diagnosis. The partial nephrectomy surgical treatment can achieve good clinical cure with good prognosis.