Introduction:
Intraoral mucosa-associated lymphoid tissue (MALT) lymphoma is a rare lymphoma that has a good prognosis if diagnosed correctly and treated in time.
Presentation of case:
A 64-year-old woman was referred to our department with asymptomatic swelling of the left hard palate. Computed tomography and magnetic resonance imaging revealed a mass in the left hard palate. We performed a pre-surgery biopsy; however, it was difficult to differentiate MALT lymphoma from other reactive lymphoproliferative disorders via gross or microscopic examination. Although the lesion was completely excised, histological findings did not allow a definitive diagnosis due to an absence of visible monoclonality. We then performed polymerase chain reaction (PCR) using DNA extracted from formalin-fixed, paraffin-embedded surgical samples. Capillary electrophoresis showed monoclonal peaks of immunoglobulin heavy chain gene rearrangement, thus facilitating a definitive diagnosis of MALT lymphoma.
Discussion:
PCR technique is rapid, accurate, and enables a definitive diagnosis without relying on traditional histological or molecular diagnostic techniques, such as Southern blotting.
Conclusion:
We suggest that, if histological examination is ambiguous or fresh material is insufficient, PCR can be performed using paraffin-embedded materials to definitively diagnose low-grade lymphomas, such as MALT lymphoma.