BackgroundThis study aims to evaluate the usefulness of endoscopic ultrasound‐guided fine‐needle aspiration cytology (EUS‐FNAC) in the diagnosis of the gastric gastrointestinal stromal tumor (GIST).MethodsWe retrospectively investigated the efficacy and accuracy of EUS‐FNAC in the diagnosis of gastric GIST. Cytological smears and cytoblock sections including immunohistochemistry and mutational studies from patients diagnosed as gastric GISTs were retrieved.ResultsThirty patients (mean age 68.8 years, range 32‐88 years, Male:Female 1:1.7) were diagnosed by cytological and cytoblock study to have GIST. The size of tumors ranged from 1.6 to 25 cm (mean 6.0 cm). 7 (23%) cases were incidentally discovered. Location was: gastric body 13 (43.3%), fundus 8 (26.7%), antrum 7 (23.3%), cardia 2 (6.7%). The study of removed tumors was correlated with the cytological findings. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 75%, 100%, 100%, 46%, and 96%. There were no false‐positive cases. The preoperative risk assessment of 27 cases with cytoblock were: none 3 (11.1%), very low 8 (29.6%), low 12 (44.4%), high 3 (11.1%), insufficient clinical data 1 (3.7%). The follow‐up varied from 2 to 120 months (mean 46.7 months). Only 1 patient of the high‐risk group died. The most frequent mutations found were those of c‐KIT in exon 11.ConclusionsPathological diagnosis was based on a combination of cytological, histopathological, and immunohistochemical features. EUS‐FNAC is a reliable, accurate, and safe method for the diagnosis of GIST. The cytoblock allows tumor risk classification and mutational study of the cases.

Evaluation of mediastinal lymphadenopathy in patients with a previous diagnosis of renal cell carcinoma (RCC) is critical for the determination of further treatment. A minimally invasive method of cytology sampling of mediastinal lymph nodes using endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has emerged as a useful tool in diagnosis. Between January 2010 and April 2018, we performed 1744 EBUS-TBNA studies of mediastinal and hilar lymph nodes for a variety of clinical indications including mediastinal malignancy. Sixteen patients (93.7% males, mean age 59.1 years, range 44-81 years) were diagnosed by cytological and cell block study to have metastatic clear cell RCC. Twelve patients had been diagnosed with clear cell RCC in the past (mean 39 months, range 4-89 months) while in four, the tumor was primarily diagnosed in the staging phase on the basis of EBUS-TBNA. The EBUS features of the mediastinal nodal masses included increase of size (mean 2.5 cm, range 1.6-3.8 cm), irregular, inhomogeneous, hypervascular, and hyperechoic echotexture. EBUS-TBNA is a procedure safe and effective for evaluating mediastinal lymphadenopathy in patients with clear cell RCC. Immunohistochemistry in the cell block is decisive for proper diagnosis. The cytologist plays a key role in the diagnosis of metastatic clear cell RCC due to the treatment implications that this neoplasm encompasses.

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