Abstract
Objective : To clarify the characteristics of reactive atypical cells (RACs) observed in 28 cases classified into the “atypical cells” (ACs) category of the new respiratory cytology reporting system of the Japan Lung Cancer Society and the Japanese Society of Clinical Cytology.
Study Design : Among sputum and transbronchial cytology specimens, 28 cases of ACs in non-sputum specimens and non-benign tumor cases were examined. The types of RACs were determined and bronchial epithelial cells (BECs) were classified as Type A (large cells with cilia) or Type B (small cells without cilia). Furthermore, the cytological findings of 12 cases diagnosed by four or more of the seven observers as suspicious for malignancy/malignancy (overdiagnosed cases) were further examined. The following were examined : background, cell count on the smears, count of atypical cells, cluster size, cluster aggregation, nuclear-cytoplasmic ratio, variation in nuclear size, cilia, nuclear chromatin, nuclear shape, nuclear margin, nucleoli, and cytoplasm.
Results : The RACs included goblet cells, type A BECs, type B BECs, type Ⅱ alveolar epithelial cells, alveolar macrophages, and squamous epithelial cells. Type A and type B BECs accounted for 64％ of the total number of ACs, with type B cells being predominant. Cases in which BECs were overdiagnosed showed higher numbers of cells on the smears, atypical cells, and large clusters than not overdiagnosed.
Conclusion : RACs observed in the ACs were shown to be of six types. BECs were predominant among the RACs. When diagnosing BECs, attention should be paid to findings that are prone to lead to overdiagnosis, as well as to recognizing type B cells.
