PMC4430206_01
Case images and clinical findings. (a) Clinical photograph of the left palatal tumor reflected in the glass. (b) Computed tomography image showing a homogeneous lesion and pressure bone resorption by the tumor (arrow). (c-e) Enhanced magnetic resonance image of the lesion. (c: T1 weighted image; d: T2 weighted image; and e: diffusion weighted image).
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Intraoral examination revealed a 30 x 23-mm mass in the left hard palate's submucosal region with intact overlying mucosal tissue (Fig. 1a). The results showed a homogeneous mass with well-delineated margins and pressure bone resorption of the hard palate (Fig. 1b-e).
Case histopathology. (a and b) Post-excision clinical photograph of the tumor. The arrow indicates an intraoperative biopsy on the oral side (a) and deep side (b). (c and d) Hematoxylin-eosin staining. The lymphocytic infiltrate is observed between the lymphoid follicles, showing hyperplasia from the germinal center to stroma deep to an oral squamous epithelium (c). High-power magnification shows a tumor composed of centrocyte-like cells with small lymphocyte-like cell infiltrates (d). (e and f) Tumor immunohistochemistry: CD20 (positive) (e) and CD3 (negative; positive at normal T-lymphocytes) (f). Original magnification (c) x40, (d-f) x400.
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The tumor was resected with an adequate safety margin of 5 mm and the palatal bone touching the tumor was shaved off along with the bone bar (Fig. 2a, b). This hyperplastic tissue was largely composed of centrocytes and centroblasts with infiltration of small lymphocyte-like cells (Fig. 2c, d). Lymphoepithelial lesions or Dutcher bodies were not observed in the fibrous tissue partitions and salivary gland tissues (Fig. 2c, d). CD79a between the lymphoid follicles. CD10 and bcl-2 positivity were observed only in the germinal center cells and nongerminal center cells, respectively. CD3 (Fig. 2f) and CD5 positivity were observed in the T-lymphocytes between follicles. Based on these histological results, MALT lymphoma was strongly suspected; however, the diagnosis was atypical follicular and interfollicular hyperplasia because of the lack of tumor cell clonality (Fig. 2).
PCR analysis of IgH rearrangements. The PCR product showed monoclonal peaks of VH(FR1)/JH, VH(FR2)/JH, and VH(FR3)/JH IgH gene rearrangement on capillary electrophoresis.
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We performed PCR using extracted DNA from the materials and observed a monoclonal peak of VH(FR1)/JH, VH(FR2)/JH, and VH(FR3)/JH immunoglobulin heavy chain (IgH) gene rearrangement on capillary electrophoresis (Fig. 3).