EVALUATION OF HISTOPATHOLOGIC CHARACTERISTICS AND CLINICAL SIGNIFICANCE OF INCIDENTAL / ISOLATED IN SITU FOLLICULAR NEOPLASIA

Abstract

ABSTRACT Introduction: Diagnosis of in situ follicular neoplasia (ISFN) limited in the physiological compartment of germinal centers is difficult, histopathologically. However, it is accepted as the early phase of lymphogenesis and/or premalignant according to recent clinical and molecular studies. INTERNATIONAL GEVHER NESİBE HEALTH SCIENCES CONFERENCE-VI/ November 13-15, 2020 Ankara/ Proceedings Book -289- Objective: It was aimed to discuss the histopathological features of ISFN. We targeted to investigate which criteria should be considered in case selection for immunohistochemical studies. In addition, the importance of diagnosis in the clinical process was tried to be interpreted. Material-Method: Between 2014-2019, hematoxylin-eosin sections and CD10, Bcl2, ki67 stained immunohistochemistry slides of seven lymph node excisions diagnosed with ISFN were re-evaluated, retrospectively. Clinical informations were obtained from the hospital information system. Results: Four of the cases were female and three were male. The average age is 49.17. The average of the largest diameters of lymph nodes was 2.07 cm. Four of the cases presented with the complaint of cervical/axillary swelling. Lymph nodes were detected incidentally in three cases. The architecture was preserved in all lymph node sections. Atypical follicles were randomly scattered and had strong expression by CD10 and Bcl2. No polarization was seen in ki67 staining. Germinal centers were of normal size, cytology was monotonous. Tingible body macrophages were absent or decreased. The number of neoplastic cells in atypical follicles was variable. Similar histopathological features were observed in the re-biopsy (in 2019) of the case in which ISFN and hyaline vascular Castleman-like changes were detected in 2014. Lymphoma development was not detected in any of the cases. Conclusion: In situ follicular neoplasia cases, in which it is difficult to determine the true incidence due to its subclinical nature, can be diagnosed infrequently. Histopathological diagnosis, in which the use of immunohistochemistry is essential, is a concern for pathologists. The fact that there was no progression to lymphoma in our case group is partially soothing. Keywords: Lymphoma, Follicular; Neoplasia; CD10; Bcl2; Ki67