Epstein-Barr virus-associated smooth muscle tumors in immunocompromised patients: Six case reports

Abstract

Background: Epstein-Barr virus associated smooth muscle tumor (EBV-SMT) is a rare oncological entity. However, there is an increasing incidence of EBV-SMTs, as the frequency of organ transplantation and immunosuppression grows. EBV-SMT diagnosis relies on histopathology and immunochemical staining to distinguish it from post-transplant lymphoproliferative disorder (PTLD). There is no clear consensus on the treatment of EBV-SMTs. However, surgical resection, chemotherapy, radiation therapy, and immunosuppression reduction have been explored with varying degrees of success.

Case summary: Our case series includes six cases of EBV-SMTs across different age groups, with different treatment modalities, adding to the limited existing literature on this rare tumor. The median latency time between immunosuppression and disease diagnosis is four years. EBV-SMTs present with variable degrees of aggressiveness and seem to have worse clinical outcomes in patients with tumor multiplicity and worse immunocompetency.

Conclusion: It is imperative to continue building on this knowledge and keeping EBV-SMTs on the differential in immunocompromised individuals.

Keywords: Case report; Epstein-Barr virus; Epstein-Barr virus-associated smooth muscle tumors; Human immunodeficiency virus; Immunocompromised; Living related kidney transplant; Orthotopic heart transplant; Orthotopic liver transplant; Post-transplant lymphoproliferative disorders; Smooth muscle tumors; Solid Organ Transplant.

Figure 1

Epstein-Barr virus associated smooth muscle tumor in the sigmoid colon in case 1. A: Proliferation of smooth muscle cells undermining and distorting the colonic mucosa (HE stain, 70 x); B: Epstein-Barr virus-encoded small RNA in situ hybridization is positive within the smooth muscle cell population (70 x, inset box 200 x).

Figure 2

Epstein-Barr virus associated smooth muscle tumor in the rectum in case 1. A: Proliferation of smooth muscle cells undermining the rectal mucosa (HE stain, 40 x); B: Epstein-Barr virus-encoded small RNA in situ hybridization is positive within the smooth muscle cell population (40 x, inset box 200 x).

Figure 3

Epstein-Barr virus associated smooth muscle tumor liver biopsies for cases 2-4 (HE stain, 200 x). Hematoxylin and eosin-stained tissue sections showed fascicles of well-differentiated spindle cells with pale eosinophilic cytoplasm and blunt-ended, ovoid nuclei with smooth nuclear contours. A, D, G: No significant cytologic atypia or nuclear pleomorphism is appreciated; B, E, H: All three cases show strong, diffuse reactivity for smooth muscle actin, confirming smooth muscle differentiation, confirming smooth muscle tumor lineage; C, F, I: Chromogenic in situ hybridization studies for the Epstein-Barr virus-encoded small RNA confirm the presence of viral genetic material in all three cases.

Figure 4

Positron emission tomography scan showing a hypermetabolic mass arising from the medial segment of the left liver lobe, measuring about 5.1 cm x 4.7 cm in the axial and anteroposterior dimension and 6.9 cm in the craniocaudal dimension in case 2.

Figure 5

Magnetic resonance imaging brain. A: T2 weighted turbo spin echo magnetic resonance images of the brain showing ring-enhancing lesion in the left temporal region in case 3; B: T1 Fl3d magnetic resonance images of the brain showing resolution of ring-enhancing lesion six years post-treatment in case 3.

Figure 6

Positron emission tomography scan showing a hypermetabolic right hepatic mass in case 3.

Figure 7

Computed tomography scan. A: The liver with intravenous contrast in arterial phase showing multiple hepatic lesions in case 4; B: The liver in venous phase showing multiple hepatic lesions in case 4.

Figure 8

Axial HASTE sequence abdominal magnetic resonance imaging. A: demonstrating numerous cystic appearing hepatic Epstein-Barr virus associated smooth muscle tumors, including the largest lesion in segment VII in case 5; B: Demonstrating stable/deceased hepatic lesions with no new lesions in case 5.

Figure 9

Axial (A) and sagittal (B) cuts of a T2 weighted magnetic resonance imaging of the thoracic spine demonstrating an Epstein-Barr virus associated smooth muscle tumor centered in the left T9/T10 neuroforamina with a rightward displacement of the spinal cord in case 6.