EBV-associated myoid tumor with lipoblast-like cells in a patient with normal immunity

Abstract

EBV-associated myoid tumor (EBVMT) comprises a specific group of soft tissue tumors with divergent histologic appearances, which typically occur in immunocompromised patients. To the best of our knowledge, there have been no previous reported of EBVMT in patients with normal immunity. EBVMT with lipoblast-like cells (EBVMT-LIC) is an extremely rare variant of EBVMT. Here, a male patient with normal immunity and EBVMT-LIC is presented. Comprehensive EBV latency expression pattern and tumorigenesis molecular analyses are performed to detail the pathologic features of this disease. Our patient was a 14-year-old who suffered from Burkitt's lymphoma 6 years ago and got complete remission for 5 years. At his last visit, he presented with pain and weakness in arms and legs. Subsequent MRI revealed an extramedullary mass at the cervical areas. CT-guided resection was then performed and comprehensive histopathologic examination was conducted. We found a haemangiopericytoma-like pattern with EBER-positive lipoblasts exist in this neoplasm and these features were in accordance with the diagnosis of EBVMT-LIC. Also, the EBV type I latency pattern was observed and the activation of Akt/mTOR pathway and Bcl-2 overexpression were found to be involved in the tumorigenesis of EBVMT-LIC. In conclusion, the results of this study suggest that EBVMT can occur in patients with normal immunity. EBV could achieve a latency type I pattern and may promote the development of EBVMT by activation of Akt/mTOR pathway and Bcl-2 overexpression. The role of chronic latent EBV infection in the development of EBVMT may be more important than previously thought.

Keywords: Akt/mTOR signaling pathway; Bcl-2 oncogene; EBV latency expression pattern; EBV-associated myoid tumor; lipoblast-like cells.

Figure 1

A. Sagittal T1-weighted image of the cervical spine showing an elliptical heterogeneous extramedullary mass (white arrow heads) at C3-C4 with no Dural tails; B. Sagittal post contrast T1-weighted image showing low density unenhanced areas with peripheral enhancement in the mass (white arrowheads); C. Intraoperative view of tumor resection; D. After resection, the extramedullary tumor appeared to be encapsulated with a clear border, ashen elliptical tubercle (size: 4 × 2.5 × 1.5 cm), and focal necrosis in the tumor border area (white arrowheads).

Figure 2

A. HPC-like pattern vessels with spindle tumor cells associated with alternating cellularity (H&E staining, magnified × 100); B. Concentric spindle tumor cells around blood vessels resembled myopericytoma (white arrowheads, H&E staining, magnified × 40); C. A large number of vacuolated cells plus spindle tumor cells (H&E staining, magnified × 100); D. High power view revealed that the vacuolated cells were lipoblast-like cells, most of which had multivacuolated cytoplasm (white arrowheads, H&E staining, magnified × 200).

Figure 3

A. Lipoblast-like cells and spindle cells are highlighted by antibodies against smooth muscle actin (IHC, magnified × 40); B. Some lipoblast-like cells and spindle cells stained with antibodies against caldesmon (IHC, magnified × 40); C. The proliferation marker Ki-67 highlighted a few lipoblast-like cells and spindle cells (IHC, magnified × 40); D. Lipoblast-like cells and spindle cells showed diffuse signals after EBER-ISH (ISH, magnified × 40).

Figure 4

A. EBER-ISH produced strong distinct nuclear staining in tumor cells (ISH, magnified × 100); B. High Bcl-2 expression was observed in spindle cells and lipoblast-like cells (IHC, magnified × 100); C. p-AKT staining was mainly localized in tumor cell nuclei (IHC, magnified × 100); D. Strong p-mTOR staining was observed in the nuclei of tumor cells (IHC, magnified × 100).

Figure 5

Indirect immunofluorescence revealed strong nuclear and cytoplasm expression of EBNA 1 in EBVMT-LIC cells (Red: EBNA 1, Blue: DABI, IF, magnified × 200).