Residency Program - Case of the Month

Clinical History

The patient was a 66-year-old woman with a past medical history of chronic hepatitis B infection (for more than 30 years – asymptomatic), hypothyroidism, hyperlipidemia, and degenerative joint disease. She also had a family history of Hodgkin lymphoma (mother). She underwent an ultrasound (due to a low GFR) that identified several hypodense lesions in both kidneys.

CT and MRI Studies

These findings were confirmed on CT scan, which suggested a clinical diagnosis of renal angiomyolipoma. Further investigation showed no clinical evidence of tuberous sclerosis. However, the MRI scan identified several similar lesions as well as a different appearing 2.6 cm mass in Segment 5 of the liver. Because the MRI with Eovist demonstrated enhancement of the mass with delayed washout, there was significant concern that this mass actually represented hepatocellular carcinoma rather than angiomyolipoma.

Management

This patient was at increased risk of hepatocellular carcinoma because of her chronic hepatitis B infection, so the possibility of hepatocellular carcinoma was a significant clinical concern. She was admitted for surgical intervention of the multiple liver masses. The patient was underwent partial hepatectomy without complication. The patient was discharged from UCDMC with close follow up in the surgical oncology clinic.

Macro- and Microscopic Description

The specimen is serially sectioned to reveal a well-circumscribed red-tan lesion located 0.9 cm to the closest margin. The hepatic masses were submitted for frozen section examination. On frozen section, it was diagnosed as an angiomyolipoma. Multiple additional representative sections are submitted for histology study and immunohistochemistry staining. Histologically, the mass was well circumscribed with a surrounding pseudocapsule of compressed tissue. The tumor parenchyma is myoid predominant containing both spindle and epithelioid shaped smooth muscle cells, with scattered thick-walled arteries and mature adipose tissue (Figure. 1-3).

Click on images to enlarge.

Figure 1		Figure 2

Figure 3

Tumor cells were diffusely positive for HMB 45 (Figure. 4).

Click on image to enlarge.

Figure 4

The tumor vascular structures were highlighted by CD31 and CD34. Reticulin and trichrome staining highlighted the abnormal tumor blood vessels. The Elastic-Trichrome staining revealed that neoplastic vascular structure is absent of internal elastic lamina (Figure 5-6).

Click on images to enlarge.

Figure 5		Figure 6

What is the diagnosis?

Choose one answer and submit.