Malt lymphoma affecting the oral cavity: a clinical, pathologic and genetic study of malt 1 gene translocation.

Objective: To investigate the clinicopathological, immunohistochemical and molecular features of MALT Lymphoma affecting the oral cavity.

Methods: Oral pathology files of a Brazilian institution were searched for cases of oral MALT lymphoma. New H&E-stained slides and immunohistochemistry reactions were evaluated for diagnosis confirmation. Molecular screening for MALT1 gene translocation was performed using fluorescent in-situ hybridization (FISH). Clinical data regarding sex, age, tumor location, clinical presentation, treatment and status at last follow-up were collected from patients' pathology files.

Results: Eleven cases were retrieved, comprising three females and four males (four unknown). Cases presented a wide age range of 35 to 75 years with a mean of 58 years, involving the hard palate (3 cases), soft palate (2 cases) and floor of mouth (3 cases). Microscopically, all cases demonstrated a diffuse proliferation of small to medium sized neoplastic cells that infiltrated normal structures. All tumors demonstrated a predominance of CD20-positive cells, but with many CD3-positive reactive T lymphocytes. BCL2 expression was positive in all cases, and negative to CD5, BCL6 and CD10, with a low Ki67 proliferation index. Five cases were investigated for genetic translocation in MALT1 gene, all of them resulted negative. All patients were treated with surgery.

Conclusion: Oral MALT lymphoma is an indolent neoplasm with a favorable prognosis. The occurrence of MALT1 translocation was not observed in the sample evaluated.