Objective : Rapid on-site cytologic evaluation (ROSE) of fine-needle aspiration cytology (FNAC) specimens and ultrasound-guided endoscopic fine-needle aspiration biopsy (EUS-FNAB) specimens was carried out not only to prevent degeneration of the obtained cells, but also to conduct quantitative and qualitative evaluation of the collected cells. As a staining method in ROSE, we examined the usefulness of simple Giemsa staining with wet fixation.

Study Design : The cellular morphology in simple Giemsa staining was compared to that in Papanicolaou re-staining after decolorization and refixation of the simple Giemsa-stained samples.

Results : We could easily observe metachromasia of the neuroendocrine granules in tumors with neuroendocrine differentiation, such as breast cancers and pancreatic tumors. The mucus, colloid and stroma in various tissues could also be well evaluated.

Conclusion : The wet fixation made it possible for us to observe the same cells by Papanicolaou re-staining. Moreover, we could obtain much information within a short screening time, and the wet fixation in the present method was considered to be safer in terms of the infection risk from the obtained materials than the dry fixation used in other staining methods. Thus, simple Giemsa staining with wet fixation appears to be very useful for ROSE.

Background : Papillary renal cell carcinoma (PRCC) is the second most common type of RCC after clear cell RCC, and is subclassified into types 1 and 2, according to the degree of nuclear atypia. Since RCC cells rarely appear in body cavity fluids, we report the cytological findings in a case of PRCC (type 2) with retroperitoneal recurrence and peritoneal dissemination.

Case : A man in his 50’s who had received maintenance hemodialysis for approximately 8 years was suspected as having a right renal tumor during follow-up. The histologic diagnosis was PRCC (type 2). One month postoperatively, peritoneal dissemination and vertebral metastasis were found. Specimens of the fluid accumulated in the excision cavity were submitted for cytological examination, which revealed clusters of atypical cells in an inflammatory background. The atypical cells contained eosinophilic cytoplasm and irregularly shaped nuclei with prominent nucleoli. The cytological diagnosis was “malignant.” Immunocytochemistry using a cell block revealed positive staining of the atypical cells for CK7, PAX8, but a negative staining result for CK20 and AMACR. Based on these findings, the lesion was diagnosed as a recurrence of PRCC.

Conclusion : When papillary clusters of atypical cells are found in a body cavity fluid, the possibility of PRCC should be included in the differential diagnosis. Diagnostic procedures including immunocytochemistry are recommended.

As fine needle aspiration (FNA) is a simple, accurate, fast, and economical diagnostic tool, it is widely used for the diagnosis of thyroid nodules. To obtain high diagnostic accuracy, FNA should be performed by persons with adequate training and experience. I have performed FNA for approximately 3000 thyroid nodules annually. Here, I present the aspiration and smearing techniques for thyroid nodules based on my experience. I conclude that cytopathologists can produce high-quality FNA materials because they can directly correlate the FNA techniques with the microscopic findings. I hope that this article serves as a trigger for cytopathologists to start performing FNA.

Fine needle aspiration (FNA) cytology is often used for definitive diagnosis of thyroid lesions, because the accuracy of qualitative diagnosis by this method is similar to that of core needle biopsy. LBC (liquid-based cytology) is useful and offers high-quality specimens for FNA cytology of thyroid tumors. LBC reduced the inadequate specimen rate and the quality of the preparations is not affected by the procedure. LBC samples offer improved diagnostic accuracy of immunocytochemistry, allowing avoidance of retesting, and also allow genetic testing, which allows more effective diagnosis.

As papillary thyroid carcinoma (PTC) has many characteristic cytological features, the diagnostic accuracy of cytology is extremely high. However, it is not easy to diagnose variants of PTC. This review describes the definitions, clinical features, cytological findings and differential diagnoses of variants of PTC. The significance of diagnosing variants of PTC by cytology is as follows : 1) Diagnosis of variants with an aggressive nature or carrying a poor prognosis is useful for determining the treatment policy and predicting the prognosis ; 2) Diagnosis of the cribriform variant facilitates determination of the surgical procedure ; 3) Familiarity with the cytological findings of the variants would enable easy differential diagnosis. When PTCs with unusual cytological findings are encountered, it is important to consider the possibility of variants.

Thyroid cancer is the most commonly encountered endocrine malignancy in clinical practice, ranging from indolent well-differentiated carcinomas (papillary thyroid carcinoma and follicular thyroid carcinoma) to aggressive poorly differentiated thyroid carcinoma, and lethal undifferentiated (anaplastic) carcinoma. Recent advances in the field of molecular biology enable assessment of histology-specific gene expressions and genetic abnormalities. Based on these evidences, molecular testing is now considered as one of the useful ancillary tools for the cytopathology of thyroid tumors.

The Bethesda System for Reporting Thyroid Cytopathology was revised according to the new proposal to include thyroid border-line lesions in the WHO Histological Classification of Thyroid Tumours (2017). This proposal was made with objective of allowing unnecessary surgeries to be avoided in thyroid cancer patients. In the United States, every patient with a malignant cytodiagnosis is generally advised to undergo total thyroidectomy and additional postoperative radiotherapy. However, unnecessary surgeries are avoided in Japan, because several treatment choices are available for the treatment of thyroid cancer. Therefore, Japanese medical associations concerned with thyroid surgery and pathology have not accepted this newly proposed category of border-line lesions, and have also refused to accept the explanatory note for border-line lesions provided in the revised Bethesda System. We believe that the basic principle of diagnosis and treatment is a discussion about what would be the best policy in daily medical practice.