Sections show a well-encapsulated nodule composed of cells forming tubules in a myxoid and focally cartilaginous stroma. Some areas are bland, while many areas (approximately 25% of the nodule) show somewhat larger cells with nuclear pleomorphism and vesiculation, prominent eosinophilic nucleoli, and occasional mitoses (4/20 HPF). These cells form tubular structures that are back-to-back. No capsular or vascular invasion is seen. The atypical cells stain positively with keratin and negatively with S-100 and GFAP.