Confirmation of immunoglobulin heavy chain rearrangement by polymerase chain reaction using surgically obtained, paraffin-embedded samples to diagnose primary palate mucosa-associated lymphoid tissue lymphoma: A case study

•Intraoral mucosa-associated lymphoid tissue (MALT) lymphoma is a rare lymphoma.•Distinguishing between MALT lymphoma from reactive lymphoproliferative disorders is a diagnostic dilemma.•To obtain a definitive diagnosis, we used polymerase chain reaction, which confirmed the diagnosis of a MALT lymphoma.

IntroductionIntraoral mucosa-associated lymphoid tissue (MALT) lymphoma is a rare lymphoma that has a good prognosis if diagnosed correctly and treated in time.Presentation of caseA 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.DiscussionPCR technique is rapid, accurate, and enables a definitive diagnosis without relying on traditional histological or molecular diagnostic techniques, such as Southern blotting.ConclusionWe 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.