Head and neck cytology is primarily performed on fine-needle aspiration cytology (FNAC) specimens, most frequently obtained from lesions of the salivary glands, lymph nodes, thyroid, and tumors originating from the nasal cavity. The practice of head and neck cytology demands extensive knowledge and experience from the observer, as it deals not only with primary tumors but also metastatic tumors, and inflammatory and infectious diseases. Tumor lesions in the salivary glands are categorized into various histological types, including pleomorphic adenoma, Warthin tumor, and malignant entities, such as mucoepidermoid carcinoma and adenoid cystic carcinoma. It is crucial to comprehend the characteristics of frequently occurring tumors while being mindful of the limitations of making a diagnosis of salivary gland lesions through FNAC. Cytological diagnosis involves morphological observations, primarily using Papanicolaou (Pap.) staining, and metachromatic findings are examined using May-Grünwald-Giemsa (MGG) staining. The advantage of MGG staining lies in its usefulness for diagnosing hematological disorders, such as lymphomas and non-neoplastic lesions. Consequently, dry specimens are prepared for MGG staining. Some malignant tumors may lack significant atypia, and conventional malignancy criteria might not suffice for a definitive diagnosis. Therefore, the diagnostic approach for salivary gland tumors involves observing individual cell atypia and inferring the direction of cellular differentiation using Pap. staining. In addition, the observation of mucin and extracellular stroma using MGG staining is crucial.

Objective : To determine the usefulness of rapid on-site cytology evaluation (ROSE) and perform a detailed evaluation of cases with atypical cells.

Study Design : The study was conducted in 254 subjects who underwent ROSE during transbronchial biopsy (TBB) or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), with the diagnoses eventually confirmed by histopathology.

The diagnostic accuracy was determined from the concordance rate of histological diagnosis in cases categorized as “suspicious for malignancy” and compared between ROSE and the final cytology report (FCR). The malignancy rate for each ROSE assessment was determined. Next, detailed examination of the findings in cases with atypical cells, including the background, pattern of arrangement of the cells, presence/absence of large solitary cells, and cytoplasmic findings was conducted and compared between the “benign” and “malignant” groups. Furthermore, the diagnostic accuracy of ROSE was re-evaluated by adding significant findings in cases with atypical cells to the “malignant” group.

Results : The diagnostic accuracy of ROSE was high ; however, the malignancy rate associated with the finding of atypical cells tended to be as high as 64.3％ (18/28). The atypical cells in the “malignant” group exhibited significant necrosis and large solitary cells, and re-evaluation of ROSE taking these two findings into account enhanced its sensitivity to the same level as that of FCR and reduced the malignancy rate to 42.9％ (6/14) for atypical cells.

Conclusion : The diagnostic accuracy of ROSE was similar to that of FCR. Presence of a necrotic background and large solitary cells could improve the diagnostic accuracy in cases with atypical cells.

Objective : The URO17^® Bladder Cancer Kit (URO17 test) is a new immunocytochemistry-based test used to detect keratin 17 (K17)-positive urothelial carcinoma (UC) cells in urinary cytology specimens. We used the URO17 test to evaluate auto-smear urine specimens.

Study Design : A total of 176 patients who underwent urinary cytology examination and received clinicopathological diagnoses within one year were enrolled in this study. Auto-smear specimens were stained using the URO17^® antibody (mouse anti-human K17). Detection of more than 20 strongly stained cells was considered as representing a positive result in the URO17 test.

Results : Clinicopathologically, 101 cases were diagnosed as having malignancy, of which 98 were cases of UC. The sensitivity and specificity of urinary cytology for detecting UC were 63.3％ and 82.1％, and those of the URO17 test were 83.3％ and 76.9％, respectively. Presence of only a few UC cells and/or low expression of K17 in some cases of UC, or high expression of K17 in some non-neoplastic urothelial cells influenced the accuracy of the URO17 test. In regard to low-grade UC, the URO17 test was positive in 14 of the 18 patients (77.8％), whereas urinary cytology indicated malignancy or suspicion of malignancy in only 6 of the 18 patients (33.3％).

Conclusions : The same samples were used for the URO17 test, a simple immunocytochemical assay for keratin 17, as for the urinary cytology. However, higher-quality urine specimens (e.g., liquid-based cytology specimens) may improve the accuracy of the URO17 test.

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.

Background : Thoracic SMARCA4-undifferentiated tumors are rare neoplasms that predominantly occur in adult males with a history of heavy smoking. These tumors manifest as large masses in the chest. Herein, we report a case in which the diagnosis was successfully made by pleural fluid cytology alone.

Case : An elderly man in his 80’s with a history of heavy smoking presented with a large tumor extending from the left pulmonary hilus to the mediastinum, along with left pleural effusion, as observed on chest CT. Cytological specimens and cell blocks were prepared from the pleural fluid. The cytological specimens revealed tumor cells that were isolated or in weakly cohesive clusters. The cytological specimen and cell block specimens stained with hematoxylin and eosin showed the presence of rhabdoid cells. Immunocytochemical staining demonstrated negative staining of the tumor cells for cytokeratin AE1/AE3, TTF-1, claudin-4, and E-cadherin in tumor cells. Expression of SMARCA4 and SMARCA2 were lost, while that of SMARCB1 was preserved. The tumor cells showed diffusely positive staining for CD34, and partial and sparsely positive staining for SOX2 and SALL4, respectively. Based on these findings, we established the diagnosis of thoracic SMARCA4-undifferentiated tumor.

Conclusion : Thoracic SMARCA4-undifferentiated tumors are highly aggressive. We demonstrated that these tumors can be diagnosed by pleural fluid cytology alone, which is especially useful, since it might be difficult to obtain tissue specimens from patients with this tumor.