FNA of a pulmonary hamartoma demonstrates a highly distinctive metachromatic matrix, reminiscent of the metachromatic stroma seen in pleomorphic adenomas. The matrix stains a bright magenta on Romanowsky stain; in tumors with a more immature fibromyxoid stroma, tissue fragments exhibit wispy edges that trail away from the center of the tissue fragment.
Cells embedded within the metachromatic matrix can be entrapped respiratory epithelial cells or mesenchymal/stromal cells.
This case was provided by Dr. Xiaoyin “Sara” Jiang, MD, is Associate Professor of Pathology at Duke University and Director of the Head and Neck Service. Her book Survival Guide to Cytopathology will be published this Summer by Innovative Science Press.