Hepatic perivascular epithelioid cell tumor: a retrospective analysis of 36 cases

Abstract

Background and aims: Hepatic perivascular epithelioid cell tumor (PEComa) is a rare type of mesenchymal neoplasm and lacks systematic reports. The aim was to analyze the features of hepatic PEComa in order to provide our own experience for diagnosis and management from a single center.

Methods: We retrospectively analyzed clinical data, imaging findings, pathology, treatments and prognosis of 36 patients with hepatic PEComa in the First Affiliated Hospital of Zhengzhou University from January 2016 to September 2023.

Results: 29 females and 7 males (median age, 47.8 years) were included in this study. The majority (26/36, 72.2%) of patients were diagnosed incidentally with non-specific symptoms. Abnormal enhancement of enlarged blood vessels (27/36,75%) can be observed on CT/MRI and only 7 patients (19.4%) were correctly diagnosed by imaging examinations. The positive immunohistochemical expressions were HMB-45(35/36,97.2%), Melan-A (34/35,97.1%), SMA (23/26,88.5%) and CD34(86.7%,26/30). Treatments include resection (24/36,67.7%), radiofrequency ablation (6/36,16.7%), transcatheter arterial chemoembolization(1/36,2.7%), conservative clinical follow-up(2/36,5.6%), and sirolimus-chemotherapy (3/36,8.3%). During the follow-up period (range, 2-81 months), except for one patient with a single intrahepatic recurrence and 3 malignant patients died in 6 months, the remaining patients had no signs of recurrence and metastasis.

Conclusions: Hepatic PEComa has no specific clinical features and mainly depends on clinicopathological characteristics for accurate diagnosis. Resection is the best treatment for benign PEComa, but TACE and radiofrequency ablation can also be considered in case of contraindications for surgery.

Keywords: PEComa; abdominal tumor; diagnosis; liver; treatment.

Figure 1

The features on Ultrasonography/dynamic CT of hepatic PEComas. Ultrasonography showed a hypoechoic mass with regular shape (A), a heterogeneous mixed echo mass (B) and a hyperechoic mass with clear boundary (C) on three different female patients, respectively. On CT scanning of a 40-year-old female patient, the plain scan showed a circular, low-density tumor with well-defined boundaries (D). Markedly inhomogeneous enhancement and abnormally dilated blood vessels can be observed in the arterial phase (E), and the enhancement decreased with washout pattern in the portal vein phase (F). (PEComa, perivascular epithelioid cell tumor; CT, computed tomography).

Figure 2

Dynamic MRI of hepatic PEComas. A 33-year-old woman with hepatic PEComa was admitted for the presence of liver mass with non-specific symptoms, who was first misdiagnosed as hepatocellular carcinoma on imagings. MRI showed a regular well-defined mass in segment IV of the liver, with hypointensity on T1-weighted images (A), hyperintensity on fat-suppressed T2-weighted images (B), and hyperintensity on diffusion-weighted images (C). The tumor was significantly heterogeneous enhanced and showed high signal in the arterial phase (D), which decreased rapidly in the portal venous phase with fast-washout pattern (E) and had a lower signal in the delayed phase in comparison with the surrounding hepatic parenchyma (F). (PEComa, perivascular epithelioid cell tumor; MRI, magnetic resonance imaging).

Figure 3

The pathological and immunohistochemical characteristics on hepatic PEComas. (A) On a 49-year-old female patient, the specimen section after resection on the left liver showed grayish yellow on the cut surface with soft texture and clear boundary. Microscopically, (B) epithelioid cells were arranged in in wheel pattern with cytoplasm ranging from eosinophilic granular to transparent, and the mature lipocytes scattered in distribution. (H&E staining, 200×). Immunohistochemistry showed the positive expressions of the tumor cells were (C) HMB-45 (magnification × 100), (D) Melan A (magnification × 100), (E) SMA (magnification × 100), and (F) CD34 (magnification × 200). (PEComa, perivascular epithelioid cell tumor; H&E, haematoxylin and eosin; HMB-45,human melanoma black 45;SMA, smooth muscle actin).

Figure 4

2-year overall survival in the entire population.