title: A minute focus of extranodal marginal zone B-cell lymphoma arising in Hashimoto thyroiditis diagnosed with PCR after laser capture microdissection: a case report.
abstract: BACKGROUND
  Primary thyroid gland lymphomas are uncommon tumours that occur in the setting of lymphocytic thyroiditis or Hashimoto's disease in almost all cases. In this condition a distinction between an inflammatory lymphoid infiltrate and a low grade lymphoma may be extremely difficult and precise criteria are necessary for a correct diagnosis.
  
  
  METHODS
  We report a case of a minute focus of primary extranodal marginal zone B-cell lymphoma (EMZBCL), incidentally discovered in a 63-year-old man with Hashimoto thyroiditis (HT) and diagnosed by means of polymerase chain reaction (PCR) after laser capture microdissection.The histological examination of surgical specimen confirmed the diagnosis of HT and showed a minute focus of dense lymphoid infiltrate (less than 4 mm in diameter), composed by centrocyte-like cells forming MALT balls. Immunoistochemistry was not useful. A microscopic focus of EMZBCL was suspected on the basis of morphological features. PCR assays revealed the rearrangement of the heavy chain of immunoglobulins only in the microdissected suspicious area, confirming the diagnosis of EMZBCL.
  
  
  CONCLUSIONS
  Our finding suggests that in cases of autoimmune thyroiditis a careful examination of the thyroid specimen is warranted, in order to disclose areas or small foci of lymphomatous transformation. Furthermore, in difficult cases with doubtful immunohistological findings, ancillary techniques, such as molecular studies, are necessary for a conclusive diagnosis.
authors.affiliation: Unit of Pathology, OO,RR, "San Giovanni e Ruggi d'Aragona", Salerno, Italy. ada66@inwind.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: D'Antonio
authors.forename: Alessia
authors.initials: A
authors.lastname: Caleo
authors.forename: Stefano
authors.initials: S
authors.lastname: Licci
authors.forename: Maria
authors.initials: M
authors.lastname: Addesso
authors.forename: Maurizio
authors.initials: M
authors.lastname: De Palma
authors.forename: Amedeo
authors.initials: A
authors.lastname: Boscaino
authors.forename: Oscar
authors.initials: O
authors.lastname: Nappi