Singapore Med J 2005; 46(1) : 31 Pictorial Essay Clinical mimicry of hepatocellular carcinoma: imaging-pathological correlation Y F A Chung, C H Thng, H F Lui, K Mancer, P K H Chow, Y M Tan, P C Cheow, L L P J Ooi ABSTRACT This pictorial essay aims to show the clinical mimicry of hepatocellular carcinoma (HCC) and its diagnostic difficulty, and to create awareness among clinicians and radiologists of potential diagnostic pitfalls. A selected consecutive series of hepatectomies with proven HCC over a three- year period, identifying clinical presentation, blood results and imaging of patients with difficult preoperative diagnosis, was reviewed. The imaging of the focal liver lesions is presented pictorially with pathological correlation. Six patients out of 34 cases of resected HCC were diagnosed to have benign (three liver abscesses) and neoplastic (one Klatskin tumour, one colorectal liver metastasis, one gallbladder cancer) conditions. Compared to the rest in the series, all six patients had normal serum alpha fetoprotein levels. On computed tomography, the mosaic appearance of HCC mimicked locules of liver abscess while HCC with pseudocapsule (rim enhancement) was misdiagnosed as unilocular abscess or metastatic lesion. Arterial enhancement on contrast-enhanced triphasic computed tomography was useful in diagnosis of HCC. In summary, HCC can mimic benign and neoplastic clinical syndromes. The diagnosis of liver abscess can delay subsequent diagnosis of HCC and potentially complicate the treatment plan. Contrast-enhanced triphasic computed tomography or magnetic resonance imaging is useful to resolve difficult diagnosis, especially when the serum alpha fetoprotein level is not raised. Keywords: alpha fetoprotein, diagnostic imaging, hepatocellular carcinoma, liver abscess, liver tumour Singapore Med J 2005; 46(1):31-37 INTRODUCTION The best chance of cure for patients with hepatocellular carcinoma (HCC) is surgery, with stage at surgery being an independent predictor of survival (1) . Early diagnosis is therefore important. This is especially so in an endemic Hepatitis B population like Singapore since Hepatitis B is a strong aetiological factor for HCC (2,3) . However, HCC may present as innocuous clinical syndromes that may delay its diagnosis and hence, treatment at a later stage. Occasionally, it may also mimic other forms of liver lesion. A search of the medical literature did not yield any report confirming this suspicion. In order to highlight such potential diagnostic pitfalls that may delay or change treatment plan, we reviewed surgical cases of proven HCC to determine their preoperative presentation and diagnosis. This pictorial essay will also help clinicians and radiologists alike to be cognizant of possible clinical scenarios that might be misleading in the diagnosis of resectable HCC. CLINICAL MATERIAL Between 2001 and 2003, 34 consecutive hepatectomies with histologically-proven HCC performed by single surgeon (CYFA) were reviewed. There were 29 men and 5 women, with a median age of 69.5 years (range 48-84 years). Eighteen (52.9%) patients were known chronic hepatitis carrier (16 hepatitis B, 2 hepatitis C). The serum alpha fetoprotein (αfp) (normal range 1-10 ng/L) was elevated in only 19 (55.9%) patients, with only 12 (35.3%) having levels above the diagnostic 400 ng/L. The majority (22) of patients had minor hepatectomy defined as three or fewer segmental resections, while 12 (35.3%) patients underwent major hepatectomy. The median size of the resected tumours was 4.8cm (range: 2.3-20cm). Eleven (32.4%) patients had macroscopic cirrhosis at time of surgery. The diagnosis of HCC was not made preoperatively or additional imaging was required to make a diagnosis of HCC in six patients. Diagnosis was difficult if the preoperative serum αfp was not raised, even with the aid of initial imaging. All the six “misdiagnosed” cases had normal serum αfp. Among the smaller tumours (<4.8cm), five (29.4%) patients had difficult diagnosis compared to only one (5.9%) patient with larger tumour size ≥4.8cm. The clinical mimicry of Department of General Surgery Singapore General Hospital Outram Road Singapore 169608 Y F A Chung, MBBS, FRCS Consultant P K H Chow, PhD, MBBS, FRCS Senior Consultant Y M Tan, MBBS, FRCS Associate Consultant P C Cheow, MBBS, MMed, FRCS Associate Consultant L L P J Ooi, MD, MBBS, FRCS Senior Consultant & Associate Professor Department of Oncologic Imaging National Cancer Centre Singapore 168938 C H Thng, MBBS, FRCR Senior Consultant Department of Gastroenterology Singapore General Hospital H F Lui, MBBS, FRCP Consultant Department of Pathology Singapore General Hospital K Mancer, MBBS, FRCPC Senior Consultant Correspondence to: Dr Alexander Y F Chung Tel: (65) 6321 4051 Fax: (65) 6220 9323 Email: gsucyf@ sgh.com.sg CME Article