Clinical History
A 57-year-old man, was admitted for evaluation of diffuse abdominal pain and weakness, which he had been experiencing over the last three months. The past medical history was unremarkable. A physical
examination, revealed right-upper quadrant tenderness.
Imaging Findings
A 57-year-old man, was admitted for evaluation of diffuse abdominal pain and weakness, which he had been experiencing over the last three months. A physical examination, revealed right-upper quadrant
tenderness. Routine laboratory studies showed derangements in liver function test results (serum glutamicoxaloacetic transaminase 60 IUL/L, gamma-glutamyl transpeptidase 315 IUL/L, lactic
dehydrogenase 284 IUL/L, alkaline phosphatase 220 IUL/l). Alpha-fetoglobulin and carcinoembryonic antigen determination were normal. An abdominal ultrasonography was done, which showed an almost
homogeneously echogenic, smoothly contoured, sharply bordered lesion, measuring 6 x 5 x 5.5 cm, in dimensions, located in the right hepatic lobe, with posterior acoustic enhancement. On Doppler
acquisition, haematic flow was depicted around the mass. Consequently, a spiral CT was performed before and after the administration of a contrast medium. On the plain CT study, the hepatic mass,
with fat tissue attenuation (-98 HU), on segment VIII, also had nodular and linear hyperdense components and was clearly margined. During the dynamic arterial and portal venous phase there was a
slight enhancement seen of the hyperdense elements of the lesion. On delayed images the lesion presented no hyperdense halo. The patient refused to undergo an MRI evaluation and the tumour was
subsequently completely resected. The histological study revealed that the mass consisted of fibrotic fat and scattered throughout were islands of myeloid tissue. The tumour was almost entirely
encapsulated by a thin fibrous septa and displaced hepatic tissue.
Discussion
Angiomyolipoma, which occurs relatively frequently in the kidney, is a rather rare, benign, mixed mesenchymal, neoplasm of the liver. Only 22 cases have been reported since the year 2000, according
to the International Liver Pathology Group. It contains vascular, adipose and muscle elements. It may occur as an isolated lesion, especially on the right hepatic lobe, in the subcapsular lesion,
with a female predominance. While renal AMLs are connected frequently with tuberous sclerosis, this association is not observed in the liver, except when it is also associated with a renal AML. The
aetiology of a hepatic angiomyolipoma is uncertain. There are at least two hypotheses, namely ectopic adrenal renal gland and liver cell metaplasia. On a CT scan, the density of the lesion varies,
depending on the relative properties of the tissue components. The presence of a high fat content, as seen in the majority of AMLs, is useful in differentiating it from a malignancy. Primary lesions
such as HCC and some metastatic lesions rarely contain a significant amount of fat. The fat rich area of an AML is enhanced in both dynamic CT and MRI images because there are many vessels in the fat
component of the tumour. Areas of fatty metamorphosis in the HCC do not enhance well because the vascularity of the fat component is generally poor. Furthermore, it is often difficult to
differentiate from other mesenchymal tumours when the amount of fat is insufficient to show ultrasonographic or CT characteristics consistent with lipomatous tumours. In such cases, more analysis
must be performed. Angiographically, the lesion is seen to be extremely vascular with large central venous lakes that persist late in the venous phase. Still, angiography as an imaging modality is no
longer used for the diagnosis of these lesions. On MRI, a high signal intensity on both T1-weighted and T2-weighted images is considered as a specific feature. Although a diagnosis may be suggested
by imaging methods, a histological confirmation remains mandatory. The preoperative identification of these tumours is desirable because of differences in clinical course and treatment between this
disease and hepatic malignant neoplasms. However, because of the rarity and pleomorphism of the histological features of hepatic AML, the histological diagnosis can be difficult, especially on needle
biopsy. Up until now, no example of hepatic AMLs with progressive metastasis has been reported; conversely, spontaneous regression has occasionally been observed. Although an angiomyolipoma is
apparently benign, this tumour can be symptomatic and may increase in size. Those that exceed 10 cm in diameter are more succeptible to acute haemmorhage. A knowledge of the imaging characteristics
of the angiomyolipoma usually allows an accurate diagnosis, although a percutaneous needle biopsy may be needed to confirm the diagnosis. Surgical excision is unnessesary unless the diagnosis is
unclear or the lesion is symptomatic. Asymptomatic, non haemmorhagic angiomyolipomas do not usually require therapy.
Differential Diagnosis List
The final diagnosis was a hepatic AML.
Final Diagnosis
The final diagnosis was a hepatic AML.
