Small-cell neuroendocrine carcinoma of the cervix accompanied by adenocarcinoma and high-grade squamous intraepithelial lesion.

Few cytological reports have described small-cell neuroendocrine carcinoma (SCNEC) in the female genital tract. In the present study, we describe a cytological case of SCNEC accompanied by adenocarcinoma, as well as high-grade squamous intraepithelial lesion (HSIL). A Japanese woman (42 years old) presented with abnormal genital bleeding. A conventional Papanicolaou smear revealed an inflammatory condition with three neoplastic components: SCNEC as irregular aggregates of neoplastic small round cells with nuclear molding and granular chromatin; adenocarcinoma as columnar cell clusters with peripherally located large nuclei, and HSIL as sheets or clusters of dysplastic basal-type squamous cells with irregular hyperchromatic nuclei. Accordingly, a cytodiagnosis of SCNEC with adenocarcinoma and HSIL was made. Owing to the rarity of cervical SCNEC, cytological diagnosis may be difficult. Due to its aggressive clinical behavior, the presence of an SCNEC component should be verified in any cytodiagnosis of adenocarcinoma or HSIL.

Useful diagnostic histogenetic features of ectopic odontogenic ghost cell tumours.

BACKGROUND: Ectopic odontogenic tumours are rare and difficult to diagnose. Consequently, they are occasionally misdiagnosed as other tumours and overtreated. Dentinogenic ghost cell tumours (DGCTs) are odontogenic neoplasms characterised by a CTNNB1 mutation, ghost cell appearance, and dentinoid-like calcification. Herein, we present a case of ectopic DGCT on the floor of a patient's mouth, providing reliable clinicopathological and genetic evidence of its odontogenicity for the first time. CASE PRESENTATION: A 72-year-old man presented with painless sublingual swelling. Imaging revealed a multi-lobulated, solid-cystic mass on the floor of his mouth. Cytological evaluation showed folded epithelial clusters composed of basaloid cells, keratinised material, and calcification. Histological analysis revealed a multi-cystic, cribriform to solid nest, with an odontogenic satellate reticulum-like epithelium, including ghost cells and dentinoid matrix deposition. Immunohistochemical analysis found that CK19, CK5/6, bcl-2, and p63 were diffuse positive, ß-catenin was focal positive in the nuclei, and the cells in the dentinoid matrix were positive for DMP1. The CTNTTB1 mutation was detected, leading to the final diagnosis of ectopic DGCT. There was no recurrence during the 6-month follow-up. CONCLUSIONS: Overall, we have presented a comprehensive clinical overview of DGCT and identified its pathological and genetic features. This report will aid in the recognition of this rare disease in the future and help to avoid misdiagnosis and overtreatment.

Fine-needle aspiration cytology of Warthin-like mucoepidermoid carcinoma: A case report with cytological review.

Warthin-like mucoepidermoid carcinoma (MEC) is a novel and rare subtype of MEC and is characterized histopathologically by the presence of abundant lymphocytic infiltration and cystic changes. A small number of cytological reports of this MEC variant is currently available. The present study reported on the sixth cytological case of Warthin-like MEC, reviewed the cytological features of the tumour and discussed the cytological differential diagnosis. A 16-year-old Japanese female presented with a painful mass in the left parotid gland. Fine-needle aspiration for cytological examination of the parotid gland tumour was performed, followed by partial parotidectomy. Cytological examination revealed sheet-like and folded epithelial cell clusters in a mucinous background accompanying abundant lymphocytic infiltration. Epithelial clusters comprised round cells with mildly enlarged round to oval nuclei, polygonal cells with relatively rich cytoplasm and slightly enlarged round to oval nuclei. Certain polygonal cells contained intracytoplasmic mucin. Histopathological examination of the resected parotid gland tumour indicated multiple cystic lesions with abundant lymphocytic infiltration accompanying lymphoid follicle formation. The cysts were lined by intermediate cells with occasional mucinous cells. Fluorescence in situ hybridization using the surgically resected specimen indicated mastermind-like transcriptional coactivator 2 (MAML2) rearrangement, a characteristic of Warthin-like MEC. Consequently, the patient was diagnosed with Warthin-like MEC. The literature review revealed that the characteristic cytological features of Warthin-like MEC are the presence of intermediate cells and lack of oncocytic cells in the mucinous material under an abundant lymphocytic background. Clinicopathological features may help with a differential diagnosis, particularly from Warthin's tumour, and detection of MAML2 rearrangement is able to improve the accuracy of diagnosis.

Usefulness and problems of cytological examination by endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis of mediastinal lymphadenopathy: A retrospective single-centre study.

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a minimally invasive and useful technique for sampling mediastinal lymph nodes. High sensitivity and specificity of EBUS-TBNA in staging lung cancer have been reported. However, few studies have addressed the results of EBUS-TBNA in the diagnosis of mediastinal lymphadenopathy with or without lung cancer, since various neoplastic and non-neoplastic conditions can involve the mediastinal lymph nodes. The present study analysed the results of the cytological examination of mediastinal lymphadenopathy using EBUS-TBNA in Kansai Medical University Hospital (Hirakata, Japan). A total of 41 consecutive patients with mediastinal lymphadenopathy who underwent EBUS-TBNA between January 2008 and December 2019 in Kansai Medical University Hospital were enrolled. This cohort included 29 males and 12 females. Cytological analyses demonstrated that 16/17 (94.1%) patients with metastatic carcinoma were diagnosed as having carcinoma (malignancy). The sensitivity, specificity and positive predictive value of the cytological examination in cases of carcinoma were 94.1, 100 and 100, respectively. However, only 3/11 (27.3%) patients with sarcoidosis were diagnosed by cytological examination. The present study demonstrated that EBUS-TBNA may be a useful method for detecting metastatic carcinoma in the mediastinal lymph nodes. However, the detection rate of epithelioid granuloma, which is a characteristic feature of sarcoidosis, was low in the present cohort. Hence, an improvement in the sampling technique is necessary.

Utility of an immunocytochemical analysis for pan-Trk in the cytodiagnosis of secretory carcinoma of the salivary gland.

Secretory carcinoma (SC) of the salivary gland is a rare distinct clinicopathological entity characterized by the presence of the ETV6-NTRK3 fusion. Although the characteristic cytological features of SC have been recognized, its cytodiagnosis, especially differentiating SC from acinic cell carcinoma, is challenging. Recent studies have revealed that immunohistochemistry for pan-tyrosine receptor kinase (Trk) and nuclear receptor subfamily 4 group member 3 (NR4A3) are specific for SC and acinic cell carcinoma, respectively. However, the usefulness of immunocytochemical detection of these markers in the diagnosis of SC has not been addressed. Hence, the present study aimed to analyze the usefulness of immunocytochemical staining for pan-Trk and NR4A3 in the cytodiagnosis of SC. We enrolled eight patients with a histopathological diagnosis of SC who underwent preoperative fine-needle aspiration cytological examination. The cytological characteristics were reviewed and immunocytochemical staining for pan-Trk and NR4A3 was performed. The characteristic cytological features noted in the patient cohort included neoplastic cell clusters with a sheet-like and papillary cluster arrangement as well as single cells. Additionally, neoplastic cells with mild to moderately enlarged nuclei and small nucleoli, multi-vacuolated cytoplasm, and intracytoplasmic mucin were also observed. The immunocytochemical analyses clearly demonstrated that all eight specimens showed positive nuclear staining for pan-Trk, but were negative for NR4A3 expression. Although all cases of SC do not always show positive immunoreactivity for pan-Trk, immunocytochemical analysis for pan-Trk may be useful for the cytodiagnosis of SC along with assessment of the characteristic cytological features.

Review of the cytological features of olfactory neuroblastoma: A retrospective single-center study.

Olfactory neuroblastoma (ONB) is a rare malignant neuroectodermal tumor. Due to the rarity, there are scarce reports describing the cytological features of ONB. Thus, we aimed to analyze these cytological features and discuss their differences depending on the histological grading of ONB. Patients with a histopathological diagnosis of ONB who underwent fine-needle aspiration cytology were enrolled in the study. The cytological features, including arrangement and shape of neoplastic cells, nuclear features, and presence of rosettes, were analyzed. Eight patients with ONB were enrolled; cytological specimens of seven patients were obtained from metastatic lesions and that of one patient were obtained from the nasal cavity tumor. The cytological specimens demonstrated variable-sized clusters of neoplastic cells and single cells. Two-cell pattern, composed of large-sized viable neoplastic cells and small-sized apoptotic cells, was noted in 3 of 4 high-grade ONBs but in none of 4 low-grade ONBs. This reflects that the presence of the two-cell pattern may represent higher proliferation in neoplastic cells. The neoplastic cells had scant cytoplasm and round to oval nuclei containing fine to granular chromatin without conspicuous nucleoli. Rosettes and paranuclear blue bodies were observed in one patient. Most cytological specimens of ONB were obtained from metastatic lesions, especially from the cervical lymph node. Thus, ONB should be differentiated from malignant lymphoma and small cell neuroendocrine carcinoma. Recognition of these cytological features of ONB while considering patient history can aid in correctly diagnosing ONBs. Moreover, the presence of two-cell pattern might reflect high-grade histology of ONB.

Spontaneous infarction of pleomorphic adenoma of the parotid gland: A case report.

Infarction after the fine-needle aspiration (FNA) procedure is a well-recognized phenomenon of salivary gland lesions. Though extremely rare, spontaneous infarction without previous FNA can occur in pleomorphic adenoma (PA). The present report describes a fourth cytological case of spontaneous infarction of PA of the parotid gland using immunocytochemical analysis, to the best of our knowledge, for the first time. A 57-year-old Japanese female presented with persistent swelling of the right neck region. Physical examination revealed a tumour in the right parotid gland, and FNA examination of the tumour was performed following surgical resection. The Papanicolaou smear demonstrated the presence of fully necrotic cell clusters of varying sizes in a necrotic background. Only a few viable cell clusters were observed. These cells were polygonal to spindle-shaped, and exhibited large round to oval nuclei with a conspicuous nucleoli. Although nuclear pleomorphism was noted, the nuclear chromatin was fine. No neoplastic myoepithelial cells were observed. Therefore, it was suspected that these cells were malignant. Immunocytochemical analysis indicated that these atypical cells were positive for p40. Histopathological examination of the resected parotid gland tumour revealed infarcted PA. Our study revealed that the presence of atypical squamous metaplastic cells in a necrotic background was a characteristic cytological feature of infarcted PA, and that these atypical squamous cells can have large nuclei with conspicuous nucleoli and exhibit pleomorphism. Although cytological diagnosis of infarcted PA is difficult, pathologists and cytopathologists must consider the presence of atypical metaplastic squamous cells in benign salivary gland tumours, including infarcted PA.

Prominent oncocytic metaplasia in pleomorphic adenoma: A potential diagnostic pitfall.

Pleomorphic adenoma (PA) is the most common salivary gland tumor. The cytological features of PA are well recognized, and its diagnosis is straightforward in most cases. Some metaplastic changes in PA are well known; however, occurrence of oncocytic metaplasia in PA is very rare. In this report, we describe the first cytological case of prominent oncocytic metaplasia in PA identified based on immunocytochemical analysis. We report the case of a 62-year-old Japanese female who presented with swelling of the left neck region. A fine-needle aspiration cytologic examination was performed followed by surgical resection. The Papanicolaou smear revealed the presence of discohesive neoplastic cells in a myxoid background. These neoplastic cells had a relatively rich, granular cytoplasm, and round nuclei with moderate pleomorphism. Initial cytodiagnosis revealed carcinoma ex PA (CXPA). Immunocytochemical analysis showed that abundant mitochondria were present in the cytoplasm of these neoplastic cells. Histopathological examination of the resected tumor demonstrated proliferation of oncocytic neoplastic cells within a myxoid material and the presence of conventional PA components. A final diagnosis of prominent oncocytic metaplasia in PA was made. Oncocytic metaplasia showed nuclear atypia and pleomorphism; therefore, CXPA, which presents with severe nuclear atypia and necrotic background, must be differentiated from oncocytic metaplastic PA. Recognition of oncocytic metaplasia in PA is important for correct diagnosis.

Cytological features of carcinoma ex pleomorphic adenoma of the salivary glands: A diagnostic challenge.

Carcinoma ex pleomorphic adenoma (CXPA) of the salivary glands is a relatively rare carcinoma. The detection rate of the carcinoma component in the cytological specimens is not high and may be challenging in cytological examination. The purpose of the present study was to analyze the cytological specimens of CXPA with emphasis on the detection of the carcinoma component. We reviewed the cytological characteristics of patients histopathologically diagnosed with CXPA who underwent preoperative cytological examination. Of the 10 patients enrolled in the study, 8 had tumors located in the parotid gland, and 2 in the submandibular gland. A review of the cytological specimens revealed the presence of the carcinoma component in all 10 cases and the pleomorphic adenoma (PA) component in 6 cases, although initial cytodiagnosis detected the carcinoma component in 8 cases. The cytological feature of this component was the presence of variable-sized clusters of polygonal cells with relatively rich cytoplasm and large round to oval nuclei in a necrotic background. Interestingly, carcinoma cells mixed with the PA component were also present. On histopathological analysis, 7 cases were intracapsular, and the remaining 3 cases were widely invasive CXPA. Further, 9 cases had salivary duct carcinoma as carcinoma component. In conclusion, these findings show that careful detection of the carcinoma cells, particularly within the PA component, is crucial for early detection of CXPA, and the presence of necrosis might help with the detection of the carcinoma component.

Neuroendocrine carcinoma diagnosis from bile duct cytological specimens: A retrospective single-center study.

Neuroendocrine carcinoma (NEC) in the extrahepatic bile duct is extremely rare and clinically aggressive. Cytological examination of bile and/or bile duct brushing specimens plays an important role in the diagnosis of carcinoma of the extrahepatic bile duct, but only a few articles have described the cytological features of NEC in this area. Thus, we retrospectively analyzed the cytological features of NEC in bile and/or bile duct brushing specimens. Patients with a histopathological diagnosis of NEC who underwent bile and/or bile duct brush cytological examination were enrolled in this study. The cytological features, including the background, arrangement, and shape of the neoplastic cells, and nuclear and cytoplasmic features were reviewed. Six patients with small cell NEC were enrolled, and two of them had pancreatic tumors directly invading the bile duct wall. The cytological specimens showed small and/or large neoplastic cell clusters with occasional single cells in all cases. The neoplastic cells had a high nuclear/cytoplasmic ratio and round-to-oval nuclei with powdery chromatin, inconspicuous nucleoli, and scant cytoplasm. Nuclear molding was a characteristic finding in all cases. One case had an adenocarcinoma component, which was also present in the cytological specimen. Cytological examination of bile and/or bile duct brushing specimens can be useful for the diagnosis of small cell NEC. This is an extremely rare but aggressive carcinoma, and its diagnosis by identifying characteristic cytological features may facilitate early detection and treatment.

Small-cell neuroendocrine carcinoma in directly sampled endometrial cytology: A monocentric retrospective study of six cases.

Small-cell neuroendocrine carcinoma (NEC) of the endometrium is extremely rare, and demonstrates an aggressive clinical course. Since reports describing its cytological features are scarce, we aimed to retrospectively analyze these features. Patients with a histopathological diagnosis of NEC who underwent preoperative cytological examination, were enrolled in this study. The cytological features including the background, arrangement, and shape of the neoplastic cells, and the nuclear and cytoplasmic features were reviewed; six patients were enrolled. The conventionally stained, directly sampled cytological specimens showed small neoplastic cell clusters in all cases, as well as isolated neoplastic cells and large clusters in 3 and 2 cases, respectively, in inflammatory or necrotic backgrounds. These neoplastic cells had a high nuclear/cytoplasmic ratio, and round to oval nuclei with powdery chromatin, inconspicuous nucleoli, and scant cytoplasm. Nuclear molding was a characteristic finding. An adenocarcinoma component was also present in 3 cases. Initial cytodiagnosis revealed small-cell NEC and adenocarcinoma or suspected adenocarcinoma in 1 and 4 cases, respectively. The one remaining case was found to be negative and was considered as degenerated endometrial stromal cells. Primarily owing to overlooking this component, the initial cytodiagnostic accuracy of small-cell NEC was low, particularly in cases with coexisting adenocarcinoma. However, the cytological features of this tumor were characteristic. Therefore, although extremely rare, careful observation is essential for an early and accurate diagnosis and to prevent overlooking the small-cell NEC component.

Utility of endoscopic ultrasound-guided fine-needle aspiration cytology in rapid on-site evaluation for the diagnosis of gastric submucosal tumors: Retrospective analysis of a single-center experience.

BACKGROUND: Recently, there have been reports of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology being used for the diagnosis of various kinds of tumors. This method has also been adopted in the diagnosis of gastric submucosal tumors (SMTs). The aim of this study was to analyze the utility of EUS-FNA cytological examination in rapid on-site evaluation (ROSE) for gastric SMTs. METHODS: Retrospective analyses of the cytological specimens of EUS-FNA in ROSE for gastric SMTs and determination of the diagnostic accuracy of EUS-FNA combined with immunohistochemical analysis of cell blocks and surgically resected specimens were performed. RESULTS: A total of 110 patients were enrolled in this study. The most common cytodiagnosis was spindle cell tumor (62 patients, 55.5%), followed by negative for tumor (34 patients), and malignant lymphoma and adenocarcinoma (five patients each). Cell blocks were prepared for 60 of the patients (96.8%), cytologically diagnosed with spindle cell tumor. Immunohistochemical analyses using cell block revealed gastrointestinal stromal tumor (GIST, c-kit+ /desmin- , 49 patients) and leiomyoma (desmin+ /c-kit- , five patients). Thus, using EUS-FNA specimens, 83.1% of GIST patients were pre-operatively diagnosed. CONCLUSIONS: EUS-FNA cytological examination in ROSE for gastric SMTs aided in the collection of sufficient amounts of tumor tissues for preparing cell blocks. This method led to a high rate of accurate pre-operative diagnosis in patients with gastric SMTs.

Cytological features of basal cell adenocarcinoma of the salivary glands.

The cytological features of basal cell adenocarcinoma (BAC) of the salivary gland, a rare carcinoma, have not been well described. This study included patients who were histopathologically diagnosed with BAC and who underwent preoperative fine-needle aspiration cytological examination. Cytological characteristics, including background, arrangement and shape of the neoplastic cells, nuclear and cytoplasmic features, and presence of stromal spindle cells, were reviewed. Seven patients were enrolled in the study. The cytological specimens were cellular and composed of large or small clusters with occasional discohesive neoplastic cells at the periphery. The predominant cellular morphology was spindle-shaped in four cases, and small round-shaped in three cases. These neoplastic cells were tightly packed, showed high cellularity and overlapping nuclei, and had mildly to moderately enlarged round to oval nuclei with occasional small nucleoli and scant cytoplasm. Stromal spindle cells were observed around the basaloid cells in three cases (42.9%). All histology-proven stromal spindle cell-positive cases had stromal spindle cells in the cytological specimens. The study findings clearly demonstrate the relatively high frequency of stromal spindle cells in cytological specimens of BAC. This finding is characteristic of BAC, although basal cell adenoma of salivary gland frequently has stromal spindle cells in the cytological specimens. The characteristic that differentiates BAC from basal cell adenoma is the presence of tightly packed and high cellular clusters with discohesive neoplastic cells. An understanding of these cytological features can aid the cytodiagnosis of BAC.

Cytological features of basal cell adenoma of salivary glands: Analysis of 19 cases emphasizing stromal spindle cells.

BACKGROUND: Basal cell adenoma (BCA) of the salivary gland is a relatively rare benign tumor. Although the presence of stromal spindle cells is a characteristic histopathological feature, this finding has not been the focus of much attention in the cytodiagnosis of BCA. Thus, we analyzed the cytological features of BCA, especially the presence of stromal spindle cells. METHODS: Patients who were histopathologically diagnosed with BCA and underwent preoperative fine-needle aspiration cytological examination were enrolled in this study. The cytological characteristics including arrangement and shape of the neoplastic cells, nuclear and cytoplasmic features, and the presence of stromal spindle cells were reviewed. RESULTS: Nineteen patients were enrolled in the study. The cytological specimens were cellular and composed of small or large clusters or both. The neoplastic cells had scant cytoplasm and small round to oval nuclei. Basement membrane-like material was observed in 57.9%, and peripheral palisading was noted in 84.2%. Loose aggregates of stromal spindle cells were present in 63.2%, and the stromal spindle cells shown in the histological examination of 85.7% of cases were expressed in the cytological specimens. CONCLUSION: This study clearly demonstrated the relatively high frequency of stromal spindle cells in cytological specimens of BCA. This finding is characteristic of BCA, and therefore, the combination of cytological features, including packed clusters of neoplastic cells with scant cytoplasm and small nuclei, peripheral palisading, and basement membrane-like material, and the presence of stromal spindle cells could increase the diagnostic success of BCA.

Cytological features of uterine carcinosarcoma: A retrospective study of 20 cases with an emphasis on the usefulness of endometrial cytology.

BACKGROUND: Carcinosarcoma of the endometrium is a relatively rare but aggressive neoplasm. Endometrial cytological features of this type of tumor have been rarely reported. This study aimed to clarify the usefulness of endometrial cytological examination in the diagnosis of endometrial carcinosarcoma. METHODS: Patients histopathologically diagnosed with endometrial carcinosarcoma who underwent preoperative endometrial or endocervical cytological examination were enrolled. The endometrial and/or endocervical specimens were conventionally stained with Papanicolaou stain, and the cytological characteristics, including arrangement and shape of the neoplastic cells, and the nuclear and cytoplasmic features were reviewed. RESULTS: Twenty patients were enrolled in the study. In the endometrial specimens, carcinomatous component was detected in almost all cases (94.4%), including those suspicious of carcinoma despite a small volume of carcinomatous cells. Sarcomatous component was observed in 6 of 18 cases (33.3%) and was significantly more frequently detected in the heterologous type (5 of 9 cases) compared to the homologous type (1 of 9 cases) (P = 0.046). In the endocervical specimens, carcinomatous component was present in 76.5% of cases, but sarcomatous component was detected in only 17.6% of cases. CONCLUSION: Although endocervical cytology can detect the carcinomatous component in more than 50% of endometrial carcinosarcoma cases, it has lesser capability to detect sarcomatous component. In conclusion, endometrial cytological examination is a more useful and accurate method to detect sarcomatous component of endometrial carcinosarcoma, particularly in the heterologous type, compared to endocervical cytological examination.

Metastatic salivary duct carcinoma in cardiac and pleural effusions: A case report with immunocytochemical analysis for androgen receptor and HER2.

Salivary duct carcinoma (SDC) is a relatively rare highly aggressive salivary gland tumor. Although SDC shows frequent lymph node and distant metastases, the presence of neoplastic cells in the pleural effusion is extremely rare. In this report, we describe the first documented cytological case of metastatic SDC in cardiac and pleural effusions with immunocytochemical analyses for androgen receptor (AR) and human epidermal growth factor receptor (HER)2. A 52-year-old Japanese male developed cardiac tamponade and respiratory discomfort after surgery and chemo-radiation therapy for SDC of the right submandibular gland. Aspiration of the cardiac and pleural effusions was performed. The Papanicolaou-stained cytological specimens of cardiac and pleural effusions showed that numerous small ball-like or papillary structures were present in an inflammatory background. The neoplastic cells had rich granular cytoplasm and large round to oval nuclei containing conspicuous nucleoli. Immunocytochemical analyses clearly demonstrated positivity for AR and strong membranous expression of HER2 in the neoplastic cells. Accordingly, a cytodiagnosis of metastatic SDC was made. Recently, HER2-targeted or AR deprivation therapy have been introduced for patients with SDC, therefore, determination of expression profiles of AR and HER2 may be crucial for developing a treatment strategy for patients with metastatic SDC. According to the results of the present report, immunocytochemical analyses for AR and HER2 in the effusion specimens may be useful for determination of a treatment strategy for patients with metastatic SDC.

Imprint cytology of strumal carcinoid of the ovary: A case report with immunocytochemical analysis.

Strumal carcinoid is a rare ovarian tumor defined as carcinoid associated with struma ovarii. We report here the second cytological case of strumal carcinoid and performed immunocytochemical analysis for the first time. A 68-year-old Japanese female was found to have a solid tumor with small cystic components in the left ovary, and bilateral salpingo-oophorectomy was performed. The Papanicolaou smear of the imprint cytological specimen of the left ovarian tumor revealed presence of two distinct components. The first component included thyroid follicles, which was composed of flat sheets of polygonal epithelial cells without nuclear groove and intranuclear inclusion. The other component was composed of trabecular clusters of columnar cells containing round to slender nuclei with "salt and pepper" chromatin. Immunocytochemical analysis revealed that synaptophysin was expressed in the latter component. Therefore, a cytodiagnosis of strumal carcinoid was made. Histopathological analyses confirmed the diagnosis of strumal carcinoid. Albeit rare, carcinoid tumor occurs in the ovary, and the recognition of characteristic nuclear features and cellular arrangement leads to correct cytodiagnosis. Presence of struma ovarii component suggests an ovarian origin. Moreover, immunocytochemical analysis for neuroendocrine markers aids its differential diagnosis from granulosa cell tumor and carcinoma arising from struma ovarii.

Cytological characteristics of meningeal solitary fibrous tumor metastatic to the lung: A case report with immunocytochemical analysis.

Solitary fibrous tumor (SFT) is a relatively uncommon mesenchymal tumor, and its occurrence in the meninges is rare. We herein report what is, to the best of our knowledge, the first cytological case of meningeal SFT metastatic to the lung with immunocytochemical analysis for signal transducer and activator of transcription 6 (STAT6), and compare the cytological characteristics to those of pleuropulmonary SFT. A 58-year-old Japanese male patient was found to have multiple nodules in the bilateral lungs after surgery for meningeal SFT. Partial resection of the nodules was performed, and touch smears were obtained. The Papanicolaou smear revealed cohesive hypercellular clusters of polygonal to elongated neoplastic cells with scant cytoplasm and oval to short spindle-shaped nuclei with nucleoli containing coarse chromatin. Mild-to-moderate nuclear pleomorphism was observed. No collagenous stroma was noted. Immunocytochemical analysis revealed that the neoplastic cells diffusely expressed STAT6. Histopathological and immunohistochemical studies confirmed the diagnosis of meningeal SFT metastatic to the lung. Moreover, reverse transcription-polymerase chain reaction analysis revealed that the lung tumor harbored NAB2ex6-STAT6ex16 fusion. Recent studies demonstrated that there is a clinicopathological difference among NAB2-STAT6 fusion variants in SFT. As reflected in fusion variants, meningeal SFT occasionally lacks collagenous stroma, as in the present case, although the most characteristic cytological feature of SFT is the presence of spindle-shaped neoplastic cells embedded in dense collagenous stroma. Thus, immunocytochemical analysis for STAT6 is very useful for diagnosing SFT.