Fig 1 

Ultrasonography of the abdomen demonstrates a large predominantly hyperechoic hepatic lesion (white arrow)

2. CT Of the abdomen performed at another institution (February 2026)

A contrast-enhanced CT abdomen performed at the referring institution reportedly demonstrated a large heterogeneously enhancing hepatic lesion with intralesional fat and significant mass effect. Based on the available report, the differential diagnosis favored hepatic adenoma and focal nodular hyperplasia.

3. Preoperative Embolization (March 2026)

In view of the giant lesion size and anticipated future liver remnant considerations, selective embolization of the left hepatic artery was performed.

The objective was to reduce tumor vascularity, facilitate compensatory hypertrophy of uninvolved hepatic parenchyma, and improve surgical feasibility (Figure 2).

Fig 2

(a) Pre-embolization angiogram demonstrates marked tumor vascularity supplied predominantly by the left hepatic artery (black arrow).

(b) Post-embolization angiogram demonstrates successful occlusion of the feeding branches of the left hepatic artery (black arrowhead) with near-complete disappearance of tumoral vascularity.

4. MRI Abdomen (March 2026 . Fig 3)

Post-embolization MRI shows a large well-defined heterogeneous lesion predominantly involving the left hepatic lobe measuring approximately 17.4 × 13.9 × 11.8 cm.

The lesion shows T1 hypointense and mildly T2 hyperintense with multiple intralesional fatty areas. Post-contrast sequences shows heterogeneous enhancement with focal regions showing arterial hyperenhancement followed by porto-venous washout (Figure 3).

The lesion is causing marked mass effect with displacement of the stomach, pancreas, portal venous structures, and right kidney.  Mild perihepatic free fluid and right pleural effusion is present.

Given the markedly elevated AFP level and evolving enhancement pattern, MRI findings were  suspicious for: Large hepatic adenoma with possible hepatocellular carcinoma transformation.

Figure 3

a) T1-weighted MR image demonstrates a predominantly hypointense hepatic lesion (white arrow).

(b) T2-weighted MR image demonstrates heterogeneous hyperintensity (white arrow).

(c,d) DWI demonstrates a linear focus of mild diffusion restriction (white arrowhead) with corresponding drop in ADC (black arrowhead), consistent with post-embolization change.

(e,f) Post-contrast image demonstrates focal arterial hyperenhancement (white arrowhead) with subsequent washout (black arrowhead).

5. Follow-Up CT Abdomen (May 2026 , Fig. 4)

Follow-up CT performed approximately two months after embolization shows a persistent large lobulated heterogeneous lesion measuring approximately 16.2 × 14.4 × 10.4 cm.

Areas of macroscopic fat and embolization material are noted within the lesion. Few areas shows  arterial phase hyperenhancement with delayed washout (Figure 4).

Persistent compression of the porta hepatis with mild intrahepatic biliary dilatation is present. Minimal ascites and right pleural effusion is seen.

Figure 4

Follow-up contrast-enhanced CT demonstrates a persistent heterogeneous hepatic mass containing post-embolization changes (black arrowheads) and areas of macroscopic fat (white arrows) .

(b) Arterial-phase CT demonstrates focal hyperenhancement within the lesion (white arrowhead).

(c) Delayed-phase CT demonstrates washout of the enhancing component (black arrowhead).

Radiological differential diagnosis:

The overall imaging suggestive of:

Large hepatic adenoma with possible malignant transformation.

Differential Diagnosis

• Hepatic Adenoma (HNF-α subtype): Large well-circumscribed lesion with intralesional fat. Predominantly occurs in young women and may demonstrate heterogeneous enhancement.

• Focal Nodular Hyperplasia: Benign hypervascular lesion usually demonstrating homogeneous enhancement and characteristic central scar. Significant AFP elevation is uncommon.

• Fibrolamellar Hepatocellular Carcinoma: Occurs in younger individuals without cirrhosis and may mimic benign hepatocellular lesions.

• Hepatocellular Carcinoma Arising in Hepatic Adenoma: Suggested by arterial hyperenhancement, delayed washout, large lesion size, and markedly elevated AFP levels.

• Giant Hepatic Hemangioma: May appear hyperechoic on ultrasound; however, elevated AFP and atypical enhancement patterns argue against this diagnosis.

Radiological Diagnosis

Large hepatocellular neoplasm, initially favored to represent hepatic adenoma, with imaging features suspicious for hepatocellular carcinoma.

Pathological Diagnosis

Hepatocellular carcinoma, favor fibrolamellar variant (extensively infarcted post-embolization specimen).

Management

Given the giant size of the lesion, progressive mass effect, markedly elevated AFP level, and persistent suspicion for malignant transformation despite embolization, the patient underwent definitive surgical resection.

Gross examination demonstrated a large encapsulated hepatic mass arising predominantly from the left hepatic lobe (Figure 5). Histopathological examination revealed extensive infarcted necrosis, likely secondary to prior embolization, with viable tumor identified only at the periphery. The viable tumor was composed of large polygonal cells arranged in nests and cords separated by thick fibrous bands. The cells demonstrated abundant eosinophilic granular cytoplasm, vesicular nuclei with prominent nucleoli, occasional binucleation and multinucleation, intracytoplasmic fat, bile pigment, hyaline globules, pale bodies, and focal Mallory hyaline. These findings were considered most suggestive of fibrolamellar hepatocellular carcinoma.

The postoperative course was complicated by a moderate right pleural effusion, which was managed with intercostal drainage (ICD) tube placement and antibiotic therapy. The patient subsequently improved clinically and was discharged in stable condition.

 Figure 5

Gross pathological specimen demonstrates a large resected hepatic mass (white arrow) with a heterogeneous cut surface. The gallbladder is identified separately (black arrowhead).

Timeline

Discussion

Fibrolamellar hepatocellular carcinoma (FL-HCC) is a rare primary hepatic malignancy that typically affects adolescents and young adults without underlying cirrhosis or chronic liver disease [1]. Unlike conventional hepatocellular carcinoma, FL-HCC frequently arises in otherwise healthy individuals and often presents as a large solitary hepatic mass, making radiological distinction from benign hepatocellular lesions challenging [1,2].

The present case illustrates the limitations of relying solely on imaging appearances when evaluating large hepatic lesions. Initial ultrasonography suggested a giant hemangioma because of the marked homogeneous hyperechogenicity of the lesion. Subsequent CT demonstrated intralesional fat and enhancement characteristics favoring hepatic adenoma or focal nodular hyperplasia. The patient's young age, absence of chronic liver disease, and lack of traditional risk factors for hepatocellular carcinoma further supported a benign radiological impression.

However, the markedly elevated AFP level of approximately 8000 ng/mL remained difficult to reconcile with a benign diagnosis. Such markedly elevated AFP levels are exceedingly uncommon in hepatic hemangioma, focal nodular hyperplasia, or uncomplicated hepatic adenoma and should immediately raise concern for hepatocellular malignancy [3]. In retrospect, the biochemical profile represented the earliest indication that the biological behavior of the lesion was discordant with its radiological appearance.

Following embolization, MRI and follow-up CT demonstrated persistent arterial hyperenhancement and delayed washout within portions of the lesion. Although embolization can alter lesion morphology and enhancement characteristics, these findings raised increasing concern for hepatocellular malignancy [3]. The evolving imaging appearances gradually aligned with the biochemical suspicion, illustrating how tumor biology may occasionally reveal the diagnosis before imaging findings become unequivocal.

Histopathological evaluation was significantly complicated by extensive infarcted necrosis resulting from prior embolization. Nevertheless, residual viable tumor demonstrated large polygonal cells with abundant eosinophilic cytoplasm, prominent nucleoli, thick fibrous bands, pale bodies, hyaline globules, and Mallory hyaline. These features are characteristic of fibrolamellar hepatocellular carcinoma and supported the final pathological diagnosis [1,4].

This case highlights an important diagnostic principle: when imaging and laboratory findings disagree, neither should be ignored. Anchoring on a benign radiological diagnosis may delay recognition of aggressive disease, particularly in young patients without conventional risk factors. Integration of clinical, biochemical, radiological, and pathological information remains essential for accurate diagnosis and management.

Conclusion

Fibrolamellar hepatocellular carcinoma should be considered in the differential diagnosis of large hepatic masses occurring in young adults without chronic liver disease. Imaging appearances may overlap substantially with benign hepatocellular lesions, creating significant diagnostic uncertainty. In the present case, markedly elevated AFP levels served as the earliest clue that the lesion's biological behavior was discordant with its apparently benign imaging appearance. Correlation of imaging, laboratory findings, treatment response, and histopathology remains essential for accurate diagnosis.

References:

1. Craig JR, Peters RL, Edmondson HA, Omata M. Fibrolamellar carcinoma of the liver: a tumor of adolescents and young adults with distinctive clinico-pathologic features. Cancer. 1980;46(2):372-379. PMID: 6245684. 

2. Ward SC, Waxman S. Fibrolamellar carcinoma: a review with focus on genetics and comparison to other malignant primary liver tumors. Semin Liver Dis. 2011;31(1):61-70. PMID: 21344352. 

3. Marrero JA, Kulik LM, Sirlin CB, Zhu AX, Finn RS, Abecassis MM, Roberts LR, Heimbach JK. Diagnosis, staging, and management of hepatocellular carcinoma: 2018 practice guidance by the American Association for the Study of Liver Diseases. Hepatology. 2018;68(2):723-750. PMID: 29624699. 

4. Torbenson M. Fibrolamellar carcinoma: 2012 update. Scientifica (Cairo). 2012;2012:743790. PMID: 24278737.

Acknowledgement:

We are thankful to the Department of General Surgery at our institution for providing us the image of the operative specimen.