Trabecular angiomyolipoma mimicking hepatic cell carcinoma

Case Report of a Hepatic Angiomyolipoma

Angiomyolipoma (AML) is a benign mesenchymal tumor that has been frequently reported in the kidney but rarely in the liver. Hepatic AML may be clinically, radiologically and morphologically difficult to distinguish from hepatocellular carcinoma or other hepatic lesions, even though the number of cases has been increasing recently due to improved imaging techniques. Histologically it consists of smooth muscle cells, adipose cells and abnormal blood vessels. It is commonly diagnosed following abdominal pain but may also be asymptomatic, has a predominant female predilection, highly variable size and occurs in subjects with a wide age range. The right lobe is the most common site, and multicentricity has been reported. Here we report a case of the myomatous variant of AML, accidentally discovered in a young woman with no clear features on radiographic examination, which was diagnosed by means of fine needle aspiration biopsy (FNAB) and then surgically removed. Although careful observation with serial radiological follow-up is an option in these cases, we chose the surgical approach because of the risk of rupture due to the large size of the lesion and the risk of malignant behavior or transformation. In case of the myomatous variant composed of irregular cells with epithelioid appearance, hepatocellular carcinoma with fatty changes or the possibility of other malignant tumors must be ruled out by immunohistochemistry (HMB-45), even in biopsy specimens.

Hepatic PEComa: a potential pitfall in the evaluation of hepatic neoplasms

Perivascular epithelioid cell tumour (PEComa) of the liver is very uncommon and may be overlooked in the clinical and histological differential diagnosis of a liver tumour. We report the case of an incidentally discovered liver mass suspicious for hepatocellular carcinoma, which on biopsy was suggestive of a pseudocyst but after resection was found to be hepatic PEComa with some of the usual characteristics of this neoplasm as well as several less familiar features. We have also reviewed cases of hepatic PEComa from the literature in order to provide insight into recognising possible PEComa preoperatively and assessing its risk of malignancy after diagnosis.

[Hepatic angiomyolipoma with variable histologic features: 8 cases resembling hepatocellular carcinoma or inflammatory pseudotumor]

BACKGROUND/AIMS

Hepatic angiomyolipoma (AML) is a rare mesenchymal tumor of the liver and demonstrates a marked histologic diversity. HMB-45 is a promising immunomarker for this tumor and especially helpful to diagnosis of some AMLs with unusual morphology. The purpose of this study was to better define the variable histologic feature of hepatic AML.

METHODS

Eight hepatic AMLs were examined, and all of that were resection specimens. The diagnosis was confirmed by the presence of HMB-45 positive cells. Median age was 41.5 years old, and mean size of tumor was 8.94 cm.

RESULTS

Conventional mixed type was 5 cases which showed myomatous, angiomatous and lipomatous component, and 3 cases were myomatous predominant. Variable patterns including spider web cell morphology, solid sheet-like and trabecular pattern were identified on myomatous component and variable amount and patterns of inflammatory cell infiltration was identified.

CONCLUSIONS

With only histologic features, it is difficult to distinguish hepatic AML from other hepatic tumor including hepatocellular carcinoma or inflammatory pseudotumor. A correct diagnosis of hepatic AML is possible by a close histologic examination with immunohistochemical stainings such as HMB-45 which is important to patient's prognosis.

Inflammatory angiomyolipoma of the liver: a rare hepatic tumor

Angiomyolipoma (AML) is a rare mesenchymal neoplasm of the tumor, composed of a varying heterogeneous mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Hepatic AML may demonstrate a marked histological diversity. We herein present one case of hepatic AML exhibiting prominent inflammatory cells in the background, which happened in a 61-year-old Chinese female patient, without signs of tuberous sclerosis. Histologically, the striking feature was the infiltration of numerous inflammatory cells in the background, including small lymphocytes, plasma cells, and eosnophils. The tumor cells were spindled and histiocytoid in shape, with slightly eosinophilic cytoplasm, and arranged along the vessels or scattered among the inflammatory background. Sinusoid structure was obviously seen in the tumor. Mature adipocytes and thick-walled blood vessels were focally observed at the boundaries between the tumor and surrounding liver tissues. The tumor cells were positive immunostaining for HMB-45, Melan-A, and smooth muscle actin. The inflammatory AML should be distinguished from other tumors with inflammatory background such as inflammatory myofibroblastic tumor and follicular dendritic cell tumor and deserves wider recognition for its occurrence as a primary hepatic tumor.

Hepatic epithelioid angiomyolipoma with trabecular growth pattern: a mimic of hepatocellular carcinoma on fine needle aspiration cytology

Epithelioid angiomyolipomas (AMLs) of the liver are rare tumors with imaging and cytologic features overlapping with those of hepatocellular carcinomas. We report the fine needle aspiration and core biopsy findings of an epithelioid AML in the right hepatic lobe of a 32-year-old female with tuberous sclerosis. She had undergone renal transplantation 8 years previously after bilateral nephrectomy for renal AMLs and a 3-cm chromophobe renal cell carcinoma. Hepatocellular carcinoma was suspected during the initial cytologic and histologic examination based on the presence of numerous large polygonal cells with ample finely vacuolated or granular cytoplasm, low nucleocytoplasmic ratio, and mild nuclear pleomorphism in the smears, as well as a distinctive trabecular histologic pattern in the core biopsies. Immunoperoxidase stains showed that the neoplastic cells were negative for cytokeratins and positive for HMB45, Melan-A, and smooth muscle actin, establishing the diagnosis of epithelioid AML. To determine the distinguishing cytomorphologic features between epithelioid AML and HCC, we have compared the cytologic features of 15 cases of hepatic AML reported in the literature, including the present case, to the FNA cytologic findings of 38 consecutive cases of HCC diagnosed at out institution.

Diagnosis and treatment of hepatic angiomyolipoma

BACKGROUND AND OBJECTIVE

Hepatic angiomyolipoma is more frequently encountered in clinical practice, its diagnosis is difficult, its treatment remains controversial. We review a single-center experience in the treatment of hepatic angiomyolipoma.

METHOD

The clinical data of 79 patients with hepatic angiomyolipoma treated at the authors' institute between January 1992 and December 2006 were retrospectively reviewed.

RESULTS

During a period of 15 years, a total of 79 patients with hepatic angiomyolipoma underwent liver resection at our hospital. There are 58 women and 21 men. The tumor size varied from 1 to 25 cm in diameter (6.1 ± 4.08). Fifty-four patients (68%) were asymptomatic. Accurate preoperative diagnosis was made in 41 patients (52%). Tumors less than 6 cm in size were more frequently misdiagnosed. Spontaneous rupture occurred in one patient. One patient had tumor recurrence 6 years after the surgery, and died of the disease 1 year later. Symptom relief was achieved in 92% of the symptomatic patients. Median survival was 90 months (90.12 ± 30.84).

CONCLUSIONS

Hepatic angiomyolipoma poses a diagnostic challenge clinically and radiologically. Surgical resection is a safe and effective treatment option. It is important to realize the potential of malignant transformation and risk of rupture as life-threatening complications.

Inflammatory angiomyolipomas of the liver: a clinicopathologic and immunohistochemical analysis of 5 cases

Hepatic angiomyolipoma (AML) may demonstrate a marked histologic diversity. We report 5 cases of hepatic AML exhibiting prominent inflammatory cells in the background (inflammatory AML). The patients were 4 females and 1 male, with age ranged from 21 to 48 years (mean, 39.2 years). Three tumors were in the left lobe and 2 in the right lobe. The tumor size was from 5.5 to 10 cm in the greatest dimension (mean, 7.46 cm). No patient had clinical features of tuberous sclerosis. Histologically, the striking feature was the infiltration of numerous inflammatory cells in the background of the tumors, including small lymphocytes, plasma cells, and histiocytes. The percentage of tumor area with heavy inflammatory infiltration was more than 50% in all cases. The myoid cells were spindled and epithelioid in shape, with eosinophilic or clear cytoplasm, and were arranged in fascicles and clusters. Scattered adipose cells and sinusoidal and thick-walled blood vessels were variably present in all tumors. Focal trabecular arrangement was present in 2 of the 5 tumors. There was no nuclear atypia, and mitotic figures were rare. The myoid cells were diffusely positive for vimentin, smooth muscle actin, and HMB-45 in all cases. All patients showed no evidence of disease after the initial surgical excision during a follow-up period from 3 to 9 years. The inflammatory AMLs should be distinguished from other tumors with inflammatory background such as inflammatory myofibroblastic tumor and follicular dendritic cell tumor.

Angiomiolipoma hepático en dos pacientes con infección por el virus de la hepatitis C

AIM

The aim of this study is to present our experience with two cases of hepatic angiomyolioma in hepatitis C virus (HCV) positive patients, and to up-date the clinical manage, diagnostic and treatment of this entity.

CLINICAL OBSERVATIONS

Both cases were presented in women in their 4-5th decade of life. Clinical presentation was with symptoms in one but incidental in the other. Both were HCV positive. Values of alpha-fetoprotein were normal. Radiological imaging was not diagnostic. Histopathological examination and immunohistochemical findings gave the diagnosis of angiomyolipoma. At time of diagnosis the size of tumours was 4.8 and 8 cm of diameter. Both cases were treated with surgery in order to definetly rule out malignancy. After 6 and 3 years of follow-up, there is no evidence of recurrence.

DISCUSSION AND CONCLUSION

The hepatic angiomyolipoma is a rare benign tumour, mimicking other liver tumours. Although no patognomonic features, there are some radiological findings that point out to the diagnosis of angiomy olipoma. Nevertheless, definitive diagnosis is done by his tological and immunohistochemical findings (HMB-45). The hepatic angiomyolipoma consists of varing proportion of three elements, mature fat cells, smooth muscle cells and blood vessels. Although it is a benign tumour, the difficulty in ruling out malignancy, prompted surgical management. It is not described its relation with HCV virus, thus we consider our cases as an coincident finding.

Pediatric liver tumors and hepatic ontogenesis: common and distinctive pathways

Several types of pediatric liver tumors exhibit structural features apparently reflecting processes which normally occur during hepatic ontogenesis: some hepatoblastomas mimic distinct phases of hepatogenesis, including the formation of mesenchymal structures closely associated with immature epithelia, and there are tumors almost exclusively consisting of complex mesenchymal patterns. Current classifications of hepatoblastomas refer to the identification of more or less mature (differentiated) single or mixed components seen in histologic preparations. These do not, however, attempt to integrate ontogenic pathways, in contrast for example, to nephroblastoma and associated lesions, where such a view has proved to be highly fruitful. Based on the fact that an enormous amount of knowledge has recently been accumulated regarding hepatic ontogenesis, time may have come to look at these tumors with a new eye. In what follows, we aim at trying to analyze distinct features of pediatric hepatic tumors (except vascular tumors) within the background of ontogenesis. Some key steps of hepatogenesis and the regulatory factors involved may, in the future, deliver an armamentarium to search for novel molecular mechanisms involved in tumorigenic pathways.