A Rare Case of Nodular Fasciitis Presenting as a Parotid Tumor: Clues to Cytodiagnosis

Abstract A 14-year-old boy presented with left preauricular painless swelling of 10 months' duration. Local examination revealed a 3 × 2-cm, firm, nodular, nonmobile mass in the left preauricular area, just in front of tragus. Fine needle aspiration yielded paucicellular smears comprising singly scattered histiocyte/myofibroblast-like spindle cells and occasional giant cells. It was reported as benign mesenchymal lesion on cytology. Left superficial parotidectomy was performed. Histopathological and immunohistochemical analysis confirmed the diagnosis of nodular fasciitis (NF). It was an ill-circumscribed cellular neoplasm, abutting and focally infiltrating into otherwise normal parotid gland. The tumor comprised spindle cells arranged in short bundles and storiform pattern with interspersed osteoclast-like giant cells, foam cells, extravasated red blood cells (RBCs), and focal areas of keloidal collagenization. The cells were positive for smooth muscle actin and negative for CD34, beta-catenin, S100, and pan-cytokeratin. Final diagnosis of NF was rendered. NF can rarely involve the parotid gland or present as parotid enlargement and pose diagnostic challenge, especially on cytology. However, in appropriate clinical context, subtle cytomorphological clues such as presence of myofibroblasts and fibrocollagenous stromal fragments can help in ruling out the commonly occurring salivary gland neoplasms and offering a definitive cytodiagnosis of NF which will be helpful in deciding the further course of management.