NEEDLE-TRACK METASTASIS AFTER TRANSTHORACIC NEEDLE-BIOPSY

Metastasis along the needle track (NTM) after a transthoracic needle b iopsy (TNB) is considered a very rare complication. A survey of the me mbership of the Society of Thoracic Radiology and a review of the Engl ish-language literature were conducted to assess the incidence of this complication and its predisposing factors and natural history. A ques tionnaire was sent to all radiology departments in the United States a nd Canada that had a senior member of the Society of Thoracic Radiolog y, The total number of TNB between 1978 and 1993 and occurrences of NT M were elicited. If an NTM was encountered, information on the size of the nodule, proximity to the pleura, histology, size of the biopsy ne edle, and the interval between biopsy and NTM and outcome of the patie nt was elicited. The incidence of NTM was estimated using binomial pro portions. Results of the literature survey were tabulated to provide s imilar information. One hundred sixty-five questionnaires were mailed and 75 responses were received. Approximately 68,346 TNB were reported . Five departments reported a total of eight NTM, resulting in an inci dence of 0.012%. The average interval between TNB and NTM was 2.6 mont hs. There were no predictable risk factors. The outcome was known in o nly 11 patients; 4 patients died by the time of reporting (2 after 14 months and 1 each after 6 and 9 months). From the results of this surv ey, the incidence of NTM after TNB is approximately 0.012%. This small risk is random and unavoidable.