• Tumor seeding after both, conventional biopsy and fine needle puncture does occur and can negate the benefits of subsequent surgery. A nice tabulation of case reports can be found in (1).
• A recent systematic review identified 179 events in 99 articles (2); the authors give the following estimates for tumor seeding:
• 2.29 % for biopsy (range 0 - 11%).
• 1.4 % for percutaneous ethanol injection (range 1.15 - 1.85) when used with biopsy
• 0.95 % for radiofrequency ablation with and 0.61 % without concomitant biopsy.
  
• Local excision may be curative (3) but major surgery might be required (4).
• For this reason, we discourage biopsy or fine needle puncture of suspect lesions. If the diagnosis cannot be made according to the EASL criteria (5), laparoscopic biopsy is usually advocated in patients with potentially curative lesions.
  

References:

1. Schotman SN, De Man R, Stoker J et al. (1999).  Subcutaneous seeding of hepatocellular carcinoma after percutaneous needle biopsy. Gut 45: 626-627. Abdelli N, Bouche O, Thiefin G, Renard P, Flament JB, and Zeitoun P. Subcutaneous Needle-Tract Seeding After Percutaneous Fine Needle Aspiration Biopsy of a Colonic Liver Metastasis. Gastroenterol.Clin.Biol. 1994; 18:652-656.
2. Cedrone A, Rapaccini GL, Pompili M, Grattagliano A, Aliotta A, and Trombino C. Neoplastic seeding complicating percutaneous ethanol injection for treatment of hepatocellular carcinoma. Radiology 1992; 183:787-788.
3. Durand F, Regimbeau JM, Belghiti J et al. (2001). Assessment of the benefits and risks of percutaneous biopsy before surgical resection of hepatocellular carcinoma. J Hepatol 35: 254-258.
4. Ishii H, Okada S, Okusaka T et al. Needle tract implantation of hepatocellular carcinoma after percutaneous ethanol injection. Cancer 1998; 82:1638-42.
5. Bruix J, Sherman M, Llovet JM et al. Clinical management of hepatocellular carcinoma. Conclusions of the 2000 EASL conference. J Hepatol 35: 421-430.