Tumour seeding after fine-needle aspiration and core biopsy of the head and neck--a systematic review.

Although fine-needle aspiration cytology (FNAC) and core needle biopsy are essential diagnostic investigations of lumps in the head and neck, seeding along the needle track has long been a concern, and various factors have been implicated. We therefore searched the Medline database for relevant English language papers published between 1970 and 2014, excluding those on the thyroid and parathyroid, and systematically reviewed them to assess the risk. In the 610 articles reviewed we found only 7 reports of seeding (5 after FNAC and 2 after core needle biopsy). Tumours were found between 3 months and 3 years after the procedure in 4 cases, and in 3, tumour cells were found along the needle track between 0 and 33 days after the procedure. The needles varied in size from 18 - 22 gauge (G) and there were 3 to 4 passes. Four cases occurred after investigation of a mass in the salivary glands, and 3 after assessment of a cervical lymph node. Disease was benign in one and malignant in 6. Seeding along the needle track after FNAC or core needle biopsy of a lump in the head and neck is rarely reported, and an accurate estimate of its incidence is difficult to ascertain. Crude estimates suggest 0.00012% and 0.0011% after FNA and core needle biopsy, respectively. A distinction should be made between seeding that is seen shortly after the procedure and the development of tumour along the needle track.