J. J. Kanitra2, J. C. Hardaway1, T. Soleimani1, N. Mehrabi2, M. K. McLeod1, S. Kavuturu1 1Michigan State University,Department Of Surgery,Lansing, MI, USA 2Michigan State University,Lansing, MI, USA
Introduction:
Adrenal Oncocytomas (AO) were first described in 1986 by Kawamoto et al. They are often incidentally identified and have previously been described as a benign, nonfunctional, female predominant tumor with an average age at diagnosis of 47. Although there are suggested immunohistochemical profiles, AO are diagnosed based on their characteristic histology. Since the literature is composed of predominately singular case reports, we took this opportunity to perform a systematic review to update the literature on AO by reviewing patient and tumor characteristics, and management trends.
Methods:
A comprehensive search was performed in PubMed, Embase, and Cochrane Library through June 15, 2017. Variables extracted included patient demographics (eg, age, sex), tumor characteristics (eg, adrenal laterality, hormonal functionality, size), management (eg, adrenalectomy + nephrectomy, open or laparoscopic, adjuvant therapy), immunohistochemical profiles, and follow-up (eg, time followed, recurrence, mortality). Malignant potential was determined by the Lin-Weiss-Bisceglia (LWB) criteria, regardless of the original authors diagnosis.
Using bivariate analysis, the patient demographics and tumor characteristics were compared between the benign, borderline, and malignant cases.
Results:
The initial search algorithm retrieved 360 citations, of which 103 were included for analysis, which described a total of 170 cases of AO. These were predominantly diagnosed in females (67%), on the left side (64%), and were nonfunctional (62%). The average age at diagnosis was 45 (2.5-81) and the median tumor size was 82 mm. The tumors stained positive for alpha-inhibin (68%), melanin-A (85%), synaptophysin (71%), vimentin (79%), mES-13 (100%), calretinin (67%), and neuron specific enolase (92%).
Of the reported AO, 38% were benign, 36% borderline and 26% diagnosed as malignant. Bivariate analysis showed that male patients were more likely to have a malignant tumor compared to females (39% vs 19%, p=0.016). There was also a statistically significant association between hormonal functionality and malignant potential (p=0.004; 44% of malignant tumors were functional, compared to 50% of benign tumors. There was no statistically significant association between malignant potential and laterality (p=0.594) or age (p=0.189). Also, there were no statistically significant associations between any immunohistochemical stain and malignant potential.
Conclusion:
In this systematic review of the literature, we found that the majority of the AO are either malignant or have a malignant potential. This finding is contrary to previous literature, which reported AO as a benign tumor. Distinguishing between benign and malignant adrenal oncocytomas has always been challenging. Since AO are a pathologic diagnosis, it is important to identify pre-operative characteristics suggestive of a malignant tumor. The follow up after an adrenalectomy should be determined based on the pathology results.