MALT lymphoma affecting the oral cavity: a clinical, pathologic and genetic study of MALT1 gene translocation

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

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.

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.

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