A 56-year-old Caucasian female was referred to Clinical Department of Abdominal Surgery, University Medical Center Ljubljana for further investigation and treatment of a growing intrahepatic mass. Initial abdominal ultrasound (US), which had been carried out 6 years previously for evaluation of nephrolithiasis, revealed a hypoechoic lesion in a segment VII of the liver. Further contrast-enhanced computed tomography (CT) scan confirmed a 15 mm hypervascular lesion in segment VII (Figure 1). Periodic follow-ups during the subsequent years revealed a progressive increase in the size of the lesion, which by the time of her referral in had grown for more than 30 mm, and reached the size of 49 mm.
In her past medical history, she underwent laparoscopic cholecystectomy due to acute calculous cholecystitis. She had no history of chronic illnesses and she took no medications. She reported intermittent pain in the right upper quadrant, which had started few weeks before the admission. Physical examination was unremarkable. Laboratory results including tumor markers alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and cancer antigen 19-9 (CA 19-9) were all within normal ranges.
Contrast-enhanced US showed a hypoechoic lesion with hyperenhancement in arterial phase that progressed from the periphery to the center and subsequent washout in the portal-venous phase. Further magnetic resonance imaging (MRI) demonstrated the same lesion, which was better defined as a 45 x 49 mm round lesion in segment VII with a hypointense signal on T1-weighted sequences and hyperintense signal on T2-weighted sequences with complete homogenous enhancement in post-contrast arterial phase and hypointense signal in hepatobiliary delayed phase (Figure 2). These findings suggested portal vein aneurysm, arteriovenous aneurysm, or hepatocellular adenoma in the differential diagnosis. Additionally, MRI showed three hepatic cystic lesions, which measured between 9 and 20 mm.
Since imaging studies were inconclusive, US-guided 18G fine needle trucut biopsy (FNTB) was performed. Biopsy specimen, measuring about 50 x 1 mm, revealed a benign mesenchymal tumor composed of bland spindle cells forming short fascicles. The nuclei of tumor cells were elongated and often cigar shaped lacking mitotic activity, while the cytoplasm was moderately abundant and eosinophilic. By immunohistochemistry, tumor cells were positive for smooth muscle actin, desmin, H-caldesmon and calponin, and were negative for CD117, DOG1, STAT6, MUC4, and wide spectrum cytokeratins. Based on the morphological features and supplemented by additional immunohistochemistry, a diagnosis of a benign smooth muscle tumor was suggested, consistent with leiomyoma.
Patient's records were presented at a hepatobiliary multidisciplinary team meeting. As tumor had grown progressively to a size of almost 50 mm and the fact that it became symptomatic, surgical removal was recommended. Thus, laparotomy was carried out in an usual manner. Surgical exploration and intraoperative US revealed a 49 x 41 mm solid mass in segment VII of the liver in close proximity to the right hepatic vein. Resection of segment VII (i.e., segmentectomy) was performed using cavitron ultrasonic surgical aspirator (CUSA) (Integra Life Sciences, NJ, USA). Furthermore, two simple hepatic cysts in segment II were also removed. Finally, a thorough abdominal and pelvic exploration with gastric and small bowel palpation was performed, all of which were unremarkable. The postoperative period was uneventful and the patient was discharged on the fifth day after surgery.
Histologic analysis revealed a well-demarcated and unencapsulated tumor within the liver (Figure 3A), composed of fascicles of bland tumor cells with elongated cigar shaped nuclei and eosinophilic cytoplasm with indistinct borders (Figures 3B,C). Mitotic activity was very low (<1 mitosis per 10 high power fields), atypical mitoses were absent. Focal palisading of the tumor cell nuclei was present at many areas (Figure 3D). The surrounding liver parenchyma was unremarkable. By immunohistochemistry, the tumor cells were diffusely positive for h-Caldesmon, calponin, and smooth muscle actin, while only about 60% of tumor cells displayed strong positivity for desmin (Figure 4). The tumor cells were negative for S100, CD34, MUC4, STAT6, C-KIT, DOG1, and CK-MNF116. In situ hybridization was negative for Epstein-Barr virus (EBV). In summary, morphological and immunohistochemical features were consistent with hepatic leiomyoma. An extensive clinical work-up failed to detect the presence of smooth muscle neoplasm outside the liver, including gastrointestinal and genitourinary tract. Therefore, a final diagnosis of a PHL was established.
At 6-month follow up, the patient is in an excellent clinical condition, with no evidence of recurrence. She continues to adhere to surveillance at every 6 months.