Actinomycosis mimicking malignancy: a report of three cases diagnosed with fine-needle aspiration cytology.

We describe three cases of actinomycosis of the head and neck area, clinically suspected to be malignancies, diagnosed by fine-needle aspiration (FNAC). The patients presented with painless, slowly growing masses in the cervicofacial area. Ultrasonography identified the masses as enlarged lymph nodes which were subsequently biopsied by FNAC. Cytological features were similar in all cases, with a background of granulocytes and scattered lymphocytes and histiocytes. At high magnification colonies of branching, filamentous and beaded bacteria were detected. In the Diff-Quik-stained smears, these filamentous colonies showed an evident yellowish color with the typical feature of the "sulfur granules" consistent with the Splendore-Hoeppli phenomenon. A diagnosis of actinomycosis was made and confirmed in all cases by the subsequent microbiological tests. The patients were treated with high-dose penicillin, which caused the masses to progressively shrink. The lymph nodal localization of cervico-facial actinomycosis may be a diagnostic challenge, because in that area, lymphadenopathies may occur both in benign and malignant conditions. FNAC is a safe, fast, and reliable method to perform an accurate diagnosis of actinomycosis avoiding the surgical excision for histological evaluation.