Angiomyolipoma (AML) is a benign mesenchymal tumour which is most frequently found in the kidney; liver is the second most common site of occurrence1. The first case of hepatic angiomyolipoma was described by Ishak in 19762. Histological features of hepatic angiomyolipoma (AML) are highly variable3. The majority of hepatic angiomyolipomas are believed to be clinically benign, however, few of the cases reveal aggressive behaviour including invasive growth pattern, recurrence after surgery and metastasis. The treatment of hepatic angiomyolipoma remains controversial4. Before the ready availability of CT scanning, the incidence of hepatic angiomyolipoma in the general population was 0.3%5. We report a rare case of hepatic angiomyolipoma in a patient of ovarian cancer.
Case Report
A 45 year old lady who was operated for ovarian cancer few years ago, presented to our hospital with chief complaints of abdominal distension and pain. CA 125 and other laboratory investigations were within normal limits. Contrast enhanced CT abdomen revealed a large lobulated heterogeneously enhancing mass involving segment IV & caudate lobe of liver. The mass was showing intra-lesional areas of macroscopic fat & vascular channels which was consistent with hepatic angiomyolipoma. She was managed conservatively and was kept on follow up.
Discussion
Angiomyolipoma is uncommon benign tumour of mixed mesenchymal origin which is most frequently discovered on abdominal ultrasound or CT scan as an asymptomatic mass. It is more commonly seen in women compared to men. The majority of patients with hepatic angiomyolipoma are asymptomatic and diagnosed incidentally7. With advent of newer imaging techniques angiomyolipoma is increasingly recognized now a days and occurs at least nine times more commonly in the kidney than any other organ8. Before ready availability of CT scanning, the incidence in the general population was 0.3%9. While the natural history of hepatic angiomyolipoma is not well known, the course of patients with unresected renal angiomyolipoma has been much better documented. Hepatic angiomyolipoma commonly presents as an asymptomatic mass however, if symptomatic; upper abdominal pain or discomfort are the most frequent complaints, as in our case. Clinical symptoms and signs of disease are not common unless a large mass is present5.
Ultrasound findings may range depending on the tissue components of the tumour. Hyperechoic mass is the more common finding due to presence of lipomatous component. However, angiomatous and myomatous component may result in hypo to anechoic areas within the tumour.1 USG Color Doppler in our patient revealed a large hyperechoic mass in liver with the presence of multiple vascular channels within. Plain CT showed heterogeneous low-density lesion with fat attenuation within and contrast enhanced CT revealed highly enhancing mass with multiple intra-lesional vascular channels. In our case, the presence of intralesional macroscopic fat and vascular channels within the mass was consistent with hepatic angiomyolipoma. However, the difficulty lies in diagnosing tumours containing myomatous tissue and the angiomatous variant.1 The differentials of hepatic angiomyolipoma includes lipoma, hepatocellular adenoma, hepatocellular carcinoma, sarcoma and metastasis. However, characteristic imaging findings in the clinical background can help in making the diagnosis. To determine the components of the tumour, MRI is considered to be the best modality. Signals characteristics (i.e. hyperintense on the T2-weighted image and hyper or hypointense on T1-weighted image) depend on the tumour tissue component. The lipomatous component may be determined as hyper-intense signals on T1 and T2-weighted image and they may also be confirmed by the chemical shift imaging technique.
Histologically, angiomyolipoma tumours are characterized by an admixture of adipose tissue, blood vessels, and smooth muscle cells in varied proportions. Hence, fine needle aspiration cytology/ biopsy has been reported to be useful in the preoperative diagnosis of this tumour.3,5
Usually majority of hepatic angiomylipomas follow benign clinical course and thus can be treated conservatively. However, few cases show aggressive behaviour in their clinical course4. Few cases may show low level of accurate diagnoses due to atypical features on imaging. As there is risk of dissemination of tumour cells in malignant tumours, biopsy is usually avoided in such cases and many of such tumours are surgically resected6.
References
- Kamimura K, Nomoto M, Aoyagi Y. Hepatic angiomyolipoma: diagnostic findings and management. Int J Hepatol. 2012;2012:410781.
- Ishak KG: Mesenchymal tumors of the liver. In ‘Hepatocellular carcinoma’.Edited by: Okuda K, Peters RL. New York: Wiley Medical; 1976:247-307.
- Kobayashi Y, Kamimura K, Nomoto M, Sugitani S, Aoyagi Y. Immunohistochemical character of hepatic angiomyolipoma: for its management. Case Rep Med. 2013;2013:298143
- Kamimura K, Oosaki A, Sugahara S, Mori S, Moroda T, Satoh O, Morita T, Kimura K, Kamura T, Nomoto M, Aoyagi Y. Malignant potential of hepatic angiomyolipoma: case report and literature review. Clin J Gastroenterol. 2010 Apr;3(2):104-10.
- Velasco-Albendea FJ, Gil-Belmonte MJ, Estébanez-Ferrero B, et al. A case report of hepatic angiomyolipoma, inflammatory subtype. Clinico-pathological characterization: a diagnostic challenge. Diagn Pathol. 2023 Apr 28;18(1):57.
- Du S, Li Y, Mao Y, Sang X, et al. Diagnosis and treatment of hepatic angiomyolipoma. Hepatobiliary Surg Nutr. 2012 Dec;1(1):19-24.