Adrenocortical oncocytic tumors: a clinicopathological analysis of 44 cases

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Objective: To study the clinicopathological features of adrenocortical oncocytic tumors (ACOT) and to compare the diagnostic values of Lin-Weiss-Bisceglia (LWB) score and Helsinki score. Methods: Forty-four cases of ACOT diagnosed at Beijing Friendship Hospital, China from March 2008 to July 2019 were histologically analyzed to evaluate their malignant potential (benign versus malignant) according to two scoring criteria. Immunohistochemical studies (EnVision method) were also used. Results: There were 23 males and 21 females with an average age of 46 years. Histologically, the tumor cells were arranged in trabecular, chrysanthemum-shaped, glandular and microcapsule structures, while clear cells were rare or absent. Most of the tumor cells were moderately atypical, and intranuclear inclusion bodies were conspicuous. Immunohistochemical staining showed that tumor cells were positive for Melan A, inhibin, Syn and calretinin. The average proliferation index was 3% in benign ACOT, about 5% in ACOT of malignant potential, and>20% in malignant ACOT. According to the LWB score, 61.4% (27/44) of the tumors were on the left side and had multiple lesions. The percentage of benign ACOT was 59.1% (26/44), malignant potential 6.8% (3/44), malignant 34.1% (15/44), respectively. Among the 15 malignant ACOT, the mitotic figures>5/50 HPF were found in 13 cases, necrosis in 11 cases and capsule invasion in 10 cases. According to the Helsinki score, 65.9% (29/44) of the tumors were benign, and 34.1% (15/44) were malignant. There was no significant difference between the two scoring standards (P>0.05). During the follow-up of 9 to 144 months, 31 patients survived without disease and 13 patients relapsed or had metastasis. Conclusions: ACOT more likely be benign than malignant. The left side is more common. Malignant tumors are prone to recurrence and metastasis. The morphological parameters (high mitotic index, necrosis, and capsular invasion) in the LWB scoring standards combined with immunohistochemical parameters (Ki-67) in the Helsinki score are helpful for the diagnosis of malignant ACOT and are important predictors of poor prognosis.