Epstein-Barr virus-associated smooth muscle tumor (EBV-SMT) is a rare neoplasm recognized in immunocompromised patients. There are less than 30 cases of EBV-SMT reported in pediatric population following solid organ transplantation. Herein, we report a case of an 8-year-old female who was incidentally noted to have multiple lesions in the liver 8 years after heart transplantation. The tumor was composed of a cellular proliferation of spindle-shaped cells with low mitotic activity. The diagnosis of EBV-SMT was confirmed by in situ hybridization for EBV-encoded small RNA (EBER) transcripts. Multiple additional lesions were detected by whole body positron emission tomography-computed tomography (PET-CT) scan 4 months after the initial finding of the hepatic lesions. Immunosuppression was switched to a mechanistic target of rapamycin (mTOR) inhibitor. We conclude that EBV-SMT should be included in the differential diagnoses in post-transplantation patients and further investigations should be performed to evaluate additional lesions. transplantation. Serial testing for EBV DNA by quantitative polymerase chain reaction (PCR) was performed on peripheral blood starting 3 years after the heart transplant (she presented with cough and fever), which showed amplification with up to 131,600 copies/mL. Her EBV viral load has been consistent since then. She developed acute abdominal pain and an appendiceal perforation was diagnosed 8 years post-transplant. Two liver masses were incidentally identified in the left and right hepatic lobes by abdominal computed tomography (CT) scan. Both appeared hypoechoic and individually measured up to 2.5 cm. Whole body positron emission tomography (PET)-CT scan was performed thereafter with no evidence of lymphadenopathy or other lesions. The mass in the right lobe was excised and found to be well circumscribed, white, and firm on gross examination. The mass in the left lobe was not removed due to its deep location.
KeywordsHistologically, the hepatic lesion was well demarcated from the adjacent liver parenchyma, and exhibited interlacing fascicles of spindle cells with eosinophilic cytoplasm and elongated, blunt-ended nuclei with stippled chromatin (Figure 1). Rare (less than 5%) primitive round cell component was identified. There was no evidence of necrosis or hemorrhage. Few small blood vessels were interspersed within the fascicles of spindle cells. Mitotic activity was less than 1 per 10 high power fields (HPF). Occasional lymphoid cells were seen at the junction between the tumor and adjacent liver parenchyma (Figure 2). Immunohistochemical (IHC) stains were performed to categorize the lesion. Smooth muscle actin ( Figure 3A) and HHF 35 ( Figure 3B) were positive, and desmin showed focal and weak equivocal staining consistent with smooth muscle origin. Ki67 showed only 1-2% of proliferative activity. EBV in situ hybridization was positive with a diffuse staining pattern (Figure 4), diagnostic of EBV infection. All these features were consistent with a diagnosis of EBV-SMT.W...