Focal liver lesions: one more example of discordance between contrast-enhanced sonography and CT pattern of enhancement.

Focal Liver Lesions: One More Example of Discordance Between Contrast-Enhanced Sonography and CT Pattern of Enhancement We would like to comment on the recent article by Dr. Wilson and colleagues [1] about discordance between contrast-enhanced sonography and CT and MRI as to patterns of enhancement of focal liver lesions. The authors should be commended on their effort to clarify this topic: albeit representing a small percentage of cases, patients with space-occupying liver lesions and discordant results between the contrast-based imaging techniques constitute a diagnostic challenge to their physicians. However, we have several questions. First, it is unclear from the Materials and Methods section what was the pathologic method of reference: percutaneous biopsy or histology on a surgical specimen? For example, in some cases of atypical liver adenoma, only surgery can definitely exclude liver malignancy [2]. Second, did the authors evaluate whether discordant results occurred more often when older sonography, CT, or MRI machines were used? In other words, could the use of different equipment have influenced their results? Third, did the authors verify whether different histomorphology, vascular architecture, or both could explain why the same category of lesions (e.g., adenoma) behaved differently after the administration of contrast agents? Could lesion size affect the results as well? Fourth, surprisingly no discordance was reported in cirrhotic patients with nodular lesions, a feature that has recently been reported in 19% of cases, but up to 22% in lesions less than 2 cm [3]. In this regard, we describe a case that recently came to our observation and can be added to Dr. Wilson and colleagues’ list of discordance due to the timing of enhancement. A 62-year-old woman with hepatitis C virus–positive liver cirrhosis was seen owing to the discovery of an 18-mm hypoechoic nodule in segment VII during routine sonography surveillance for hepatocellular carcinoma (HCC). Contrast-enhanced sonography with an aqueous suspension of phospholipid-stabilized microbubbles filled with sulfur hexafluoride (SonoVue, Bracco) and triple-phase helical CT were performed. An HCC-like pattern of contrast medium diffusion was observed on contrast-enhanced sonography—that is, homogeneous perfusion in the early arterial phase and washout in the portal and parenchymal phases (Figs. 1A and 1B), whereas CT displayed a hypovascular lesion in the late phases of iodinated contrast perfusion without enhancement in the arterial phase (Figs. 1C and 1D). Given the discordant imaging results, a sonographically guided biopsy was performed and a sample was obtained with an 18-gauge semiautomatic biopsy needle (Biomol, HS). Morphologic and immunophenotypic examinations of the sample yielded the diagnosis of extranodal marginal zone lymphoma, a subtype of B-cell peripheral neoplasms [4]. On the basis of the results of the staging workup, we concluded that the nodule was a low-grade B-cell primary hepatic lymphoma. This case, just as those presented by Dr. Wilson and colleagues [1], stresses the necessity of using biopsy whenever discordant results emerge between CT and contrast-enhanced sonography, especially in small nodular lesions arising in a cirrhotic liver, as suggested by the guidelines established by the American Association for the Study of Liver Diseases for the management of HCC [5]. A wrong diagnosis, as for the patient we described herein, or a delayed diagnosis may put patients at risk for incorrect management. Giampiero Francica Gaetano Lapiccirella Presidio Ospedaliero “S. Maria della Pietà” Casoria, Italy References 1. Wilson SR, Kim TK, Jang HJ, Burns PN. Enhancement patterns of focal liver masses: discordance between contrast-enhanced sonography and contrast-enhanced CT and MRI. AJR 2007; 189:123;[web]W7–W12 2. Grazioli L, Federle MP, Brancatelli G, Ichikawa T, Olivetti L, Blachar A. Hepatic adenomas: imaging and pathologic findings. RadioGraphics 2001; 21:877–892; discussion 892–894 3. Bolondi L, Gaiani S, Celli N, et al. Characterization of small nodules in cirrhosis by assessment of vascularity: the problem of hypovascular hepatocellular carcinoma. Hepatology 2005; 42:27–34 4. Loddenkemper C, Longerich T, Hummel M, et al. Frequency and diagnostic patterns of lymphomas in liver biopsies with respect to the WHO classification. Virchows Arch 2007; 450:493–502 5. Bruix J, Sherman M; Malpractice Guidelines Committee, American Association for the Study of Liver Diseases. Management of hepatocellular carcinoma. Hepatology 2005; 42:1208–1236