Imprint Cytology of Metastatic Sialoblastoma: A Case Report

BACKGROUND: Sialoblastoma is a rare, aggressive and potentially malignant perinatal/congenital tumor that recapitulates the developing salivary gland. There is only 1 brief description of the cytologic findings of metastatic sialoblastoma and 1 poorly documented case of lung metastasis in the literature. CASE: A 75-month-old girl with a history of recurrent sialoblastoma initially diagnosed at 21 months and treated with multiple incomplete surgical excisions, chemotherapy and radiation presented with a solitary lung nodule. Imprint smears and frozen section of the mass were diagnostic of metastatic sialoblastoma. CONCLUSION: Cytologic features of sialoblastoma showed complete concordance with histology and included the presence of variably arranged, tight, solid clusters of atypical-appearing, basaloidlike cells in a background of dispersed epithelial and myoepithelial cells. The clusters contained admixed benign ductal cells and dense, metachromatic, magenta hyaline globular material with smooth, rounded outlines. The differential diagnoses include neoplasms composed of either basaloid cells and/or admixed hyaline matrix material and included pleomorphic adenoma, basal cell adenoma and adenoid cystic carcinoma. All these neoplasms affect patients in the first 2 years of life, whereas sialoblastoma usually occurs in the first 2 decades of life.