Original ReportVariations in the size of focal nodular hyperplasia on magnetic resonance imagingVariación de tamaño de la hiperplasia nodular focal mediante resonancia magnética☆
Introduction
Focal nodular hyperplasia (FNH) is the second most frequent benign liver lesion after hemangioma. It is present in more than 3% of the population, prevailing among young women, although it may occur in both sexes and in all age groups.1 Microscopically, FNH is made up of normal hepatocytes, Kupffer's cells and blood vessels, surrounded by fibrous septa containing a variable number of primitive biliary conduits.2 Although its etiology is not proved, it seems that a preexisting congenital vascular anomaly or a vascular malformation trigger the hyperplastic stimulus.3
FNH is usually asymptomatic and it is frequently detected incidentally in liver radiologic studies performed for other causes. In this lesion, spontaneous rupture is very rare and malignant transformation is even more so. Therefore, after accurate diagnosis with the current image methods, treatment is conservative and only clinical follow-up must be established and then by means of medium- and long-term image tests.4
Conventional MR and dynamic studies after administration of contrast offer, using strict image criteria, a greater sensitivity and specificity in the diagnosis of FNH as compared to echography or TC.5, 6, 7 In the last few years, MR specificity to characterize FNH has increased with the introduction of hepatobiliary contrasts, which have caused specificity to come close to 100%, which avoids the need to perform other invasive diagnostic techniques and procedures.8, 9 Histological study of the samples obtained by means of percutaneous biopsy has, in addition, certain limitations especially at the hands of pathologists with limited experience in these lesions.10 MR has greater sensitivity (74–78%) than either echography (20%) or CT (60%)5, 6 to detect the central FNH scar. Moreover, it is more sensitive than echography to detect FNH lesions, due to the fact that the lesion's echogenicity is similar to that of the adjacent parenchyma, and it has the advantage of not using ionizing radiations such as CT. That is why MR is considered the image test of choice for characterizing and following up these benign focal hepatic lesions.
Medium-long term FNH follow-up by means of image tests do not generally show changes in the size of the nodules,11, 12 although on occasion both lesion regression and progression have been documented.13, 14, 15 However, serial MR studies comparing the size of lesions are few.11, 12, 13
The objective of this study is to evaluate the degree of variation of FNH size by means of contrasted MR dynamic images given this test's maximum sensitivity to delimit lesions, so as to know FNH natural history.
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Material and methods
MR images of 30 patients presenting a definite FNH diagnosis were reviewed as well as at least 2 MR examinations. The definite diagnosis was by histology or by typical criteria in MR. All the subjects belonged to 2 hospitals and the sample was obtained from a 10-year retrospective search (2000–2010). None of the patients had a history of chronic hepatopathies or primary neoplasia.
The patients signed an informed consent in writing to use a contrast medium in MR and the use of their data in
Results
In the MR images to diagnosis, all the hepatic lesions presented typical behavior, except for one scar that did not take up in the tardive phase and one lesion that presented a signal intensity slightly below the surrounding hepatic parenchyma in the balance and tardive phases. None of the lesions had fat in the echo gradient sequences in the opposite phase or capsule in the tardive phase. A central scar was detected in the pre-contrast study in 16 (36%) of the 44 lesions, of which 13 (81%)
Discussion
The summary of the findings in our work is that most (80%) of the FNH showed stable size, 16% shrank and 4% grew during MR follow-up.
The advance in quality and the increasing frequency of the use of modern image techniques to study the abdomen have made it possible to detect and diagnose FNH without the need for histological confirmation. Several articles published recently show that MR is the most accurate diagnostic technique for this objective.5, 6, 7, 8, 9 Using strict, widely-accepted
Authors
- 1
Person responsible for the study's integrity: CRF, LMB.
- 2
Conception of the study: CRF and LMB.
- 3
Design of the study: CRF and LMB.
- 4
Data acquisition: CRF, AT, ADV and CM.
- 5
Data analysis and interpretation: CRF and LMB.
- 6
Statistical treatment: CRF and LMB.
- 7
Bibliographic search: CRF.
- 8
Writing of the paper: CRF and LMB.
- 9
Critical revision of the manuscript with intellectually relevant contributions: LMB, AT, ADV, CM.
- 10
Approval of final version: CRF, LMB, AT, ADV, CM.
Conflict of interests
The authors declare that they do not have any conflict of interests.
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Please cite this article as: Ramírez-Fuentes C, Martí-Bonmatí L, Torregrosa A, del Val A, Martínez C. Variación de tamaño de la hiperplasia nodular focal mediante resonancia magnética. Radiología. 2013;55:499–504.