1. Cytomorhologic features of lymphoid neoplasms in the mediastinum and pitfalls in diagnosis

Abstract

<h3>Background</h3> Lymphoid neoplasms are challenging for most cytopathologists. In the mediastinum, rapid diagnoses have applied through cytology or during frozen sections to separate surgical from non-surgical cases. <h3>Aim</h3> To describe the cytomorphological features of mediastinal lymphoid neoplasms with tissue correlation and relative pitfalls. <h3>Method</h3> Cases of mediastinal neoplasms of guided procedures or frozen sections were reviewed. Smears from guided cytology stained with Diff-Quik and/or Papanicolaou's reagent, and cyto-logical imprints stained with Diff-Quik from frozen tissue specimens were retrieved. Cytomorphological findings were described. These were correlated with histological sections and confirmed by immunohistochemical studies. <h3>Result</h3> Of 50 anterior mediastinal cases, nine interpreted as lymphoproliferative were reviewed, two of which were diffuse large B-cell lymphoma. Two were nodular sclerosing Hodgkin's lymphoma (HD) and the other one was a composite Hodgkin's and non-Hodgkin's lymphoma (NHL). One case was NHL. Two cases were diagnosed with lymphoma versus thymoma. The last case was HD but on tissue correlation and immunohistochemistry panel, revealed embryonal carcinoma with seminomatous areas. <h3>Conclusion</h3> A mixed population of lymphoid cells may be suggestive of NHL. A polymorphous appearance with large cells having lobated nuclei is suggestive of HD. Germ cell tumours in the mediastinum may mimick the cytomorphological features of HD. Reed-Sternberg cells display more irregularly shaped nuclei compared to nuclei of immature germ cells. In a monomorphic population of lymphoid cells the so-called lymphocyte with handles is a neoplastic feature. Occurrence of cells with pale, oval nuclei could be an epithelial cell and should correctly consider thymoma. Awareness of cytomorphological pitfalls of lympho-proliferative lesions with tissue correlation and immunohistochem-istry is almost always crucial.