hepatic angiomyolipoma

Hepatic

angiomyolipoma • Hepatic angiomyolipoma - Ganzer Fall bei Radiopaedia

Radswiki T, Hepatic angiomyolipoma. Case study, Radiopaedia.org (Accessed on 12 Dec 2022) https://doi.org/10.53347/rID-11583 • CC by-nc-sa 3.0 (modified)

Hepatic

angiomyolipoma • Hepatic angiomyolipoma - Ganzer Fall bei Radiopaedia

Schubert R, Hepatic angiomyolipoma. Case study, Radiopaedia.org (Accessed on 12 Dec 2022) https://doi.org/10.53347/rID-20088 • CC by-nc-sa 3.0 (modified)

Hepatic

angiomyolipoma • Renal and hepatic angiomyolipomas in tuberous sclerosis - Ganzer Fall bei Radiopaedia

Gerstenmaier J, Renal and hepatic angiomyolipomas in tuberous sclerosis. Case study, Radiopaedia.org (Accessed on 12 Dec 2022) https://doi.org/10.53347/rID-29280 • CC by-nc-sa 3.0 (modified)

Malignant

hepatic epithelioid angiomyolipoma with recurrence in the lung 7 years after hepatectomy: a case report and literature review. Imaging of primary hepatic AML. a Plain CT showed a low-density mass in segment 5 of the liver. b, c Enhanced CT showed a tumor with hemorrhagic and necrotic changes, with early arterial phase staining and late phase washout

surgicalcasereports.springeropen.com • CC-by-4.0

Laparoscopic

hepatectomy for hepatic angiomyolipoma with preoperative diagnosis of other malignancy: a report of 2 cases. Images of case 1. a Arterial-phase contrast-enhanced CT image obtained in case 1. The tumor exhibited early enhancement (arrow: the tumor). b Delayed-phase contrast-enhanced CT image obtained in case 1. The tumor was not enhanced in the delayed phase (arrow: the tumor). c Resected specimen from case 1. The cut surface of the specimen contained a circumscribed solid tumor, which was light brownish in color (arrow: the tumor). d Hematoxylin and eosin (HE) staining of the tumor in a low-power field. The tumor cells exhibited sheet-like growth, were spindle-shaped to polygonal, and contained granular to clear cytoplasm. Adipocytes and blood vessels were present in the tumor. Extramedullary hematopoiesis was also seen (arrows). e HMB-45 staining of the tumor in a low-power field. The tumor was positive for HMB-45. f α-SMA staining of the tumor in a low-power field. The tumor was positive for α-SMA

surgicalcasereports.springeropen.com • CC-by-4.0

Laparoscopic

hepatectomy for hepatic angiomyolipoma with preoperative diagnosis of other malignancy: a report of 2 cases. Images of case 2. a Contrast-enhanced CT image obtained in case 2 at the time of the first surgery (for the right mature cystic teratoma). The tumor measured 10 mm in diameter (arrow: the tumor). b Contrast-enhanced CT image obtained in case 2 at 2 years after the first surgery. The tumor measured 20 mm in diameter and possessed various components, including an adipose component (arrow: the tumor). c Resected specimen from case 2. The cut surface of the resected specimen contained a light brownish and yellow tumor, which measured 20 mm in diameter (arrow: the tumor). d HE staining of the tumor in a high-power field. The tumor consisted of a mixture of adipocytes, spindle-shaped cells, and epithelioid cells. Large atypical epithelioid cells with eosinophilic to clear cytoplasm were also identified. e HMB-45 staining of the tumor in a low-power field. The tumor was positive for HMB-45. f: α-SMA staining of the tumor in a low-power field. The tumor was positive for α-SMA

surgicalcasereports.springeropen.com • CC-by-4.0

Hepatic

angiomyolipoma • Hepatic angiomyolipoma - Ganzer Fall bei Radiopaedia

Molinari A, Hepatic angiomyolipoma. Case study, Radiopaedia.org (Accessed on 12 Sep 2023) https://doi.org/10.53347/rID-161582 • CC by-nc-sa 3.0 (modified)

Primary

hepatic perivascular epithelioid cell tumors: imaging findings with histopathological correlation. A 35-year woman with hepatic angiomyolipoma. The non-enhanced CT (a) showed a round well-circumscribed homogeneous hypoattenuated mass in the caudate hepatic lobe. On the arterial phase (b), the tumor demonstrated significantly heterogeneous enhanced surrounded by a dysmorphic vessel (arrow). On the portal venous (c) and delayed (d) phases, the enhancement decreased, but still showed higher density compared to the surrounding liver. The MRI (e, T1WI in-phase; f, T1WI out-of-phase; g, fat-suppressed T2WI) images showed hypointense on T1WI and hyperintense on T2WI. Note the fat showed signal intensity decreased on out-of-phase image as compared with in-phase image and low signal intensity on fat-suppressed T2WI (arrow). On hepatocyte-specific agent enhanced MRI (h, arterial phase; i, portal venous phase; j, delayed phase; k, hepatobiliary phase), the tumor showed the same enhancement on arterial, portal venous and delayed phase images as CT and marked hypointensity of the tumor relative to the liver parenchyma on the hepatobiliary phase image. Ultrasound (l) showed a well-defined heteroechoic mass in the liver

cancerimagingjournal.biomedcentral.com • CC-by-4.0

Radiopaedia • CC-by-nc-sa 3.0 • de

Hepatic angiomyolipoma (HAML) is an uncommon benign hamartomatous hepatic mass lesion, containing blood vessel (angioid), smooth muscle (myoid) and mature fat (lipoid) components. There is an association with tuberous sclerosis, although this is less strong than for renal AMLs.

Clinical presentation

Most reported cases of angiomyolipoma are detected incidentally.

However, initial presentation as acute abdominal pain related to intratumoral hemorrhage and intraperitoneal hemorrhage has been reported.

Pathology

Pathologically, an AML is an unencapsulated lesion with vascular, smooth muscle and mature fat components. Angiomyolipoma fat content can vary from less than 10% to more than 95%. Fat component is made up of mature yellow fat cells. At the microscopic examination, epithelioid smooth muscle cell and proliferating blood vessels are visible.

It may be classified histologically according to the amount of fat content into several subtypes:

mixed
lipomatous (>70% fat)
myomatous (<10% fat)
angiomatous

Immunohistochemical staining of the tumor cells reveals HMB-45 positivity. Among hepatic tumors, HMB-45 reactivity is found exclusively in the smooth muscle cells AML .

Associations

There is a reported correlation between hepatic angiomyolipoma and tuberous sclerosis (TS), although the association is not as strong at it is for renal AMLs. Up to 20% of renal AMLs are associated with TS, compared to only 6% of hepatic AMLs . Nonetheless, the liver is the second most frequent site of angiomyolipoma after kidney.

Radiographic features

Angiomyolipomas may be single or multiple, round or lobulated fat-containing mass lesions, seen more commonly in the right hepatic lobe.

The characteristic findings on any modality are the presence of both fat and prominent vascularity in the same lesion. If the fatty component predominates, it resembles lipomas but most of the time, a mixture of usual solid soft tissue intermingled with fatty components will be seen. Conversely, in cases of less fatty content and excess vascular part, the lesion seems like hypervascular hepatic mass lesions.

The drainage vein of AML is the hepatic vein, and identifying a perfusing vein communicating with the hepatic vein from the tumor center can aid in differentiating AML from fat-containing hepatocellular carcinoma (HCC) .

Ultrasound

It may be seen as hetero or homogenous echogenic (due to fat content) mass lesion. In the case of less fat content and excess vascular component, angiomyolipoma can be seen as a heterogeneous hypoechoic mass lesion. Could be indistinguishable from a hemangioma.

CT

On non-enhanced CT, angiomyolipoma presents as well defined solid heterogeneous mass containing markedly hypodense area. Due to the presence of the vascular component, marked enhancement in the arterial phase is evident. Drainage is via the hepatic veins, and this is the main differentiating point from fat-containing HCC that drains mainly in the portal vein.

NECT
- well-defined mass with heterogeneous attenuation values due to the presence of fat and soft tissue densities
- maybe predominantly low-density mass
arterial phase: significant enhancement in the arterial phase
portal phase: becomes hypoattenuated

MRI

On MRI the lesion shows hyperintensity like as fatty tissue on both T1 and T2, which decreases with fat suppression. To detect the small volume of fat content in cases of lipid-poor AML, chemical shift imaging (i.e. in-phase/out-of-phase) is useful.

Signal characteristics

T1
- fatty components show hyperintensity on T1WI
- loss of signal on fat suppressed sequences
- in cases of poor lipid-content in phase/out of phase will show loss of signal at out of phase
T2: fatty components show hyperintensity on T2WI
T1 C+ (Gd): enhancement of vascular component in arterial phase

Treatment and prognosis

Observation is the method of choice for asymptomatic cases. However, cases with severe abdominal pain or intraperitoneal bleeding not responding to conservative treatment can be treated successfully with embolization and/or surgical resection.

Differential diagnosis

General imaging differential considerations include:

hepatocellular carcinoma (HCC) with a fatty component
- typically the fatty content is minimal and is in a scattered pattern
- AFP is elevated and HMB-45 in cell staining is negative
focal fatty infiltration
- poorly defined borders without pressure effect on adjacent vessels
hemangioma
- may be indistinguishable on ultrasound
hepatic lipoma
- very uncommon
- should contain no soft tissue component and never shows enhancement after contrast administration
metastasis from liposarcoma/teratoma
- extremely uncommon