Growth rate analysis of lung metastases appearing 18 years after resection of cutaneous adenoid cystic carcinoma. Case report and review of the literature

Growth rate analysis of lung metastases of a cutaneous adenoid cystic carcinoma, which appeared 18 years after the resection of the primary tumor from the scalp is presented. The doubling times of the metastases were long compared with that of other lung metastases. They were 22 months for the metastasis in the right lung and 70 months for the metastasis in the left lung, with a shortening of the doubling time in the left side to 10.4 months in the last 4 months of observation. Backward extrapolation showed that the metastases to the lung were disseminated before the diagnosis and surgical resection of the primary tumor. To our knowledge, this is the third reported case of lung metastases from a cutaneous adenoid cystic carcinoma out of 25 documented cases. We present a review of the literature and discuss the clinical implications of our findings.