Nodular fasciitis of the parotid gland: A challenging diagnosis on FNA

Background: Nodular fasciitis (NF) is a clonal, self-limited proliferation that has only rarely been described in the parotid gland. Because of its potential to mimic benign and malignant parotid neoplasms clinically, radiographically, and cytomorphologically, NF is often managed with unnecessary surgery, which is associated with a risk for significant surgical complications. The purpose of this study is to present the clinical and cytomorphologic findings for NF of the parotid gland by fine-needle aspiration (FNA). Methods: The pathology archives of the authors’ respective institutions were searched for salivary gland FNA cytology specimens with a confirmed diagnosis of NF. The clinical history, pathologic diagnosis, cytomorphologic findings, and immunocytochemical results were recorded. Results: A total of 15 cases were identified; the average age was 37 years, and 10 patients (66.7%) were female. Five cases (33.3%), all treated surgically, showed recurrence within an average timeframe of 1.6 months. Only 3 cases (20.0%) were classified as definitive, probable, or suggestive of NF. On average, smears were composed of predominantly single (69.2%), spindled cells (100.0%) with short unipolar (76.9%) and/or bipolar processes (38.5%), round (61.5%) or elongated (84.6%) nuclei, and inconspicuous nucleoli (53.8%). In 69.2%, a tissue-culture appearance was shown, and 76.9% contained myxoid stroma. In 46.2%, a minimal amount of cytologic atypia was shown. Conclusions: Keeping NF in the differential for any bland, single, spindled cell proliferation with elongated cytoplasmic processes and bland nuclei may prompt the clinician to consider more conservative management in the correct clinical context.