Actinomycosis of the posterior triangle: a case report and review of the literature.

Actinomycosis presents acutely as an abscess, or as a chronic lesion mimicking malignancy, tuberculosis, or aspergillosis. Most disease involves the mouth and its immediate site of lymphatic drainage, the anterior triangle of the neck. We present a case of actinomycosis at the apex of the posterior triangle, suspected of being a malignancy, and discuss the importance of being aware of this as a cause of neck lumps. The diagnosis is usually made late because of the difficulties in culturing the organism, or in identifying characteristic 'sulphur granules' in pus or biopsy specimens. For these reasons, the disease is underdiagnosed. When acute or chronic neck lesions prove difficult to diagnose, microscopy and prolonged anaerobic culture of pus and biopsy specimens should be performed in addition in Ziehl-Neelsen staining, tuberculosis and fungal cultures. The tests should be repeated if negative. Specific treatment requires prolonged courses of antibiotics, despite adequate surgical excision, to prevent relapse.