Lipomatous lesions of the parotid gland. Potential pitfalls in fine needle aspiration biopsy diagnosis.

Nine cases of benign fatty tumors of the parotid studied initially by fine needle aspiration (FNA) biopsy and subsequently diagnosed by open biopsy were reviewed. All lesions presented as enlargements of the parotid gland. The cytologic diagnoses were correct in only five of the nine cases. While four of six FNA samples from lipomas were correctly diagnosed by cytology, the other two samples were classified as inadequate. Three cases of diffuse infiltration of the parotid by mature-appearing adipose tissue were cytologically characterized as "no diagnostic change" in two cases and sialosis in one case. The clinical, radiologic, cytologic and histologic features of these tumors are described to increase the familiarity of cytologists with these lesions, which may prevent unnecessary surgical intervention in some patients.