Purpose To investigate leptin expression and distribution in the tissue of lacrimal gland epithelial tumours, and leptin concentration in the tears secreted by these tumours.

Methods Clinical records and microscopic slides of six pleomorphic adenoma (PA), three adenoid cystic carcinoma (ACC), and one chronic sclerosing dacryoadenitis (CSD) cases were reviewed. Normal-appearing gland tissue adjacent to tumours from patients with PA served as controls. Tissue leptin expression and distribution were assessed using leptin immunohistochemistry staining. Preoperative and postoperative leptin concentrations in tears were measured in the tumour-affected eye in two patients with PA, two with ACC and one with CSD, and in the contralateral eye in one patient with ACC and one with CSD.

Results Moderate cytoplasmic staining was observed in all tumour-adjacent morphologically normal tissue, PA, ACC and CSD tissues. ACC tissues revealed moderate nuclear staining in tumour cells, whereas other tissues did not reveal leptin nuclear staining (p=0.012). Leptin in tears was not detected in the eyes of patients with PA preoperatively and postoperatively. However, leptin was detected in tears of patients with ACC and CSD preoperatively, and its concentration markedly decreased at 1 month postoperatively. Leptin was not detected in any sample from the contralateral eyes of patients for which such samples were available.

Conclusions The leptin concentration in tears was greater in patients with ACC than in those with PA. Leptin nuclear staining was only observed in the ACC tissue. Further investigations should be conducted to identify the cause and significance of these findings.