[Clinicopathologic features and prognosis of adenoid cystic carcinoma of external auditory meatus]

Objective: To investigate clinicopathologic features and prognosis of adenoid cystic carcinoma (ACC) involving external auditory meatus. Methods: The clinical presentation and follow-up data of 63 patients with ACC of external auditory canal were collected from January 2006 to February 2017 at PLA General Hospital and Hainan Branch of PLA General Hospital. The clinicopathologic features and prognostic factors of external auditory canal ACC were analyzed. Results: (1) There were 28 males and 35 females and the average age of the first diagnosis was 48.9 years (22-81 years). The tumors showed cribriform pattern in 35 cases (15 cases of late stage), tubular pattern in 14 cases (8 cases of late stage), and solid pattern in 14 cases (9 cases of late stage). Cases with solid pattern was relatively more frequent than that of cribriform pattern and tubular pattern, but the difference was not statistically significant (P>0.05). (2) The average follow-up time was 62.4 months (2-228 months) in the 57 available cases. Among the 33 cases with recurrence, 18 cases had local recurrence and 15 cases had distant metastasis. The mean recurrence time was 40.6 months (2-204 months). Nine patients died of ACC: 2 cases in early stage (died at 48 and 102 months after the first treatment), 7 cases in late stage and 57 with (died at 9, 30, 32, 60, 72, 94 and 228 months). (3) Among the 37 patients with perineural invasion, there were 21 cases of cribriform pattern, 4 cases of tubular pattern and 12 cases of solid pattern; the number of cases in early stage and late stage were 15 and 22, respectively; and the differences were statistically significant (P<0.05). In addition, 31 cases had otalgia among the 37 patients with perineural invasion, where differences were not significant (P>0.05). (4) Thirty of 45 cases with tumor resection or partial resection of temporal bone had recurrence, whereas 3 of 12 cases of tumor combined with superficial lobectomy of parotid gland had recurrence. The difference was statistically significant (P<0.05). Postoperative adjuvant radiotherapy was given in 19 cases, including 7 cases of early stage (2 cases of recurrence), and 12 cases of late stage (8 cases of recurrence), among which there was no significant difference (P>0.05). Conclusions: ACC occurring in external auditory canal frequently recurs. Superficial parotid lobectomy at the first operation is necessary to prevent tumor recurrence. Postoperative adjuvant radiotherapy has certain curative effect on patients with early stage tumor, but it does not affect the recurrence rate. Patients at late stage are more prone to perineural invasion than those in early stage. In addition, cribriform and solid patterns are more common that tubular pattern, and there is no significant correlation between perineural invasion and otalgia.