Cytological features of a lymphoepithelial cyst of the salivary gland with application of the second edition of Milan System for Reporting Salivary Gland Cytopathology.

Lymphoepithelial cysts (LECs) of the salivary glands are relatively rare, benign cystic lesions. Characteristic histopathological features of LEC include presence of well-circumscribed unilocular cysts surrounded by dense lymphoid tissue with lymphoid follicles. These cysts are lined by a combination of squamous, ciliated, columnar and mucous epithelia. Fine-needle aspiration (FNA) cytology is the standard preoperative diagnostic procedure for salivary gland lesions. Although the cytological diagnosis of cystic salivary gland lesions is difficult, the use of Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) in the cytodiagnosis of cystic salivary gland lesions has been reported. However, only a few studies have described the cytological features of LEC. To the best of our knowledge, the present study reviewed the cytological features of a case series of LEC and evaluated the application of MSRSGC for the first time. This retrospective study included 13 patients with LEC of the salivary glands who underwent pre-operative FNA followed by surgical resection of the cyst. All the lesions were present in the parotid gland. Cytological analysis revealed no epithelial cell component in eight patients (62.5%) along with a proteinaceous background containing lymphocytes and/or foamy cells. Non-keratinising squamous epithelium was observed in three patients. Amylase crystalloids were noted in two patients. None of the patients were cytodiagnosed with LEC. Eight, three, one and one patients were categorised as MSRSGC I, II, III, and IVa, respectively. The results of the present study demonstrated that cytodiagnosis of LEC was difficult due to the absence of epithelial component in 62.5% of the specimens. However, evaluation of its benignity was not difficult. Thus, it can be summarized that MSRSGC may be useful for cytological evaluation of LECs.

[Effectiveness of deep breath-hold SPECT in torso area: examination concerning improvement of resolution].

Because SPECT images are acquired under normal respiration, the respiratory motion induces artifacts and decreases resolution. In this study we developed a novel method of acquiring SPECT data during deep inhalation breath-hold (BrST) and assessed its efficacy in reducing motion artifacts and improving resolution. Reproducibility studies found that variations in SPECT image homogeneity were reduced using the BrST method to within a clinically non-problematic range. An experiment using a custom-built respiration phantom showed almost complete elimination of motion artifacts and significant improvement in resolution using the BrST method. Clinical assessment confirmed a significant reduction in motion artifacts along with the improvement in resolution. The BrST method enabled visualization of lesions that previously had been impossible to detect by standard acquisition under normal respiration. The BrST method is expected to both significantly reduce motion artifacts and improve resolution.