Background : Solitary fibrous tumor (SFT) are rare tumors arising from the soft tissues. We encountered a patient with a SFT that was located between the middle and lower lobes of the right lung.

Case : The patient was a 40-year-old Japanese woman ; chest CT performed 9 years earlier revealed a smooth mass in the lung (17 mm in diameter). The mass had grown slightly since and at the present consultation, CT showed a mass measuring 22×15 mm in size, containing air. Based on the findings, a pleural tumor was suspected and thoracoscopic partial resection of the right middle lobe was performed. Cytologically, sheet-like cell clusters were observed, composed of regularly arranged cells. The tumor cells contained round-to short-spindle-shaped nuclei with fine and evenly distributed chromatin. No evidence of bleeding or necrosis was found in the background of these slides. Histologically, the tumor was composed of fibrous tissue with numerous spindle-shaped cells and vessels with dilated, branching, and hyalinized staghorn-like (hemangiopericytoma-like) structures. Immunohistochemically, the tumor cells showed positive staining for CD34 and weakly positive staining for STAT6, and the tumor was diagnosed as a SFT.

Conclusion : For final diagnosis of SFT, not only tumor cytology, but also comprehensive diagnostic evaluations, including radiological, histological, and immunohistochemical evaluations, are necessary.

Background : Cytopathological examinations of the parathyroid glands are performed only rarely, and tumor lesions of the parathyroid glands are not easy to diagnose on the basis of cytology. We report a case of parathyroid adenoma that was diagnosed by fine-needle aspiration cytology (FNAC) using the liquid-based cytology (LBC) method.

Case : An 82-year-old male patient presented to us with suspected hyperparathyroidism on the basis of an elevated PTH level and hypercalcemia, but CT and ultrasonography indicated a right thyroid tumor. FNAC of this tumor was performed and cytopathological specimens were prepared using the LBC method. The cells in the specimens showed clear and rich cytoplasm, and the nuclei were small and round. Immunocytochemical staining showed negative staining of the tumor cells for TTF-1 and calcitonin, and positive staining of the cells for chromogranin-A. The Ki-67 index was 2%. Based on these findings, the tumor was diagnosed as a “parathyroid adenoma”. The tumor was later resected and the diagnosis was confirmed by histopathology.

Conclusion : Although it is not easy to diagnose parathyroid adenoma by FNAC, a correct diagnosis proved possible in the present case by adding immunocytochemical analysis to the cytomorphologic examination.

Background : Anaplastic large cell lymphoma (ALCL) developing during treatment for chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is very rare. We report an extremely rare case of ALCL that developed during treatment for CLL/SLL.

Case : A 30-year-old man who had been diagnosed as having CLL/SLL two years earlier presented with recurrent enlargement of the cervical to mediastinal lymph nodes after they had once previously been reduced by chemotherapy. We suspected CLL/SLL transformation and performed a right cervical lymph node biopsy. Cytological examination of the lymph node showed diverse shapes and sizes of the tumor cell nuclei, including some multilobed, horseshoe-shaped, and doughnut-shaped nuclei. Immunohistochemically, these cells were positive for CD4, CD30 and TIA-1, and negative for CD20, CD23, CD79a, EMA and ALK. Therefore, we made the final diagnosis of ALK-negative ALCL.

Conclusion : We report a case of ALCL that developed during the course of CLL/SLL. Careful confirmation of the diagnosis based on the morphology, immunohistochemistry and clinical findings is necessary, even if recurrence of CLL/SLL is strongly suspected.

Background : Primary signet ring cell carcinoma occurs more frequently in the stomach, and rarely in the lung. We report a case of solid adenocarcinoma (anaplastic lymphoma kinase [ALK]-positive) of pulmonary origin exhibiting signet ring cell morphology diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) biopsy.

Case : A man in his 50 s visited our medical center complaining of hoarseness of the voice. After computed tomographic imaging, 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) showed lung cancer with multiple lymph node and bone metastases. It was judged that lymph node metastasis from solid adenocarcinomas can exhibit signet ring cell morphology on EBUS-TBNA cytology.

The gastric cancer was not detected by endoscopy. Histological examination of a biopsy specimen obtained from a left supraclavicular lymph node revealed atypical cells that showed positive immunohistochemical staining for TTF-1 and ALK. Thus, we made the final diagnosis of lymph node metastasis from ALK-positive adenocarcinoma.

Conclusion : Solid adenocarcinomas exhibiting signet ring cell morphology could arise from any organ. Primary lung carcinomas with signet ring cell morphology are often ALK-positive, and evidence of ALK expression by immunostaining leads to effective treatment.

Background : Salivary gland tumors are known to sometimes exhibit various metaplastic changes. Mucous metaplasia is rare in Warthin tumors, and the cytological distinction between the Warthin-like variant of mucoepidermoid carcinomas (MEC) and a Warthin tumor with mucous metaplasia can be challenging. Here we report a case of Warthin tumor with mucous metaplasia of the parotid gland.

Case : A male in his 60 s with a history of smoking presented with a painless mass in the right parotid gland that measured about 30 mm in diameter. Fine-needle aspiration cytology revealed sheet clusters of bland epithelial cells containing pale light-green cytoplasm with mucous metaplastic cells in the focal lymphocytic background. The typical oncocytic epithelium of a Warthin tumor was observed in focal areas, but none of the intermediate/squamous and mucous cells that are characteristic findings in MEC were seen in the smears. The tumor was a typical Warthin tumor with bilayered oncocytic epithelium and basal cells with a lymphoid stroma, and mucous metaplastic cells were found in both the cysts and solid area. Fluorescence in situ hybridization of the surgically resected specimen did not show any evidence of MAML2 (mastermind-like transcriptional coactivator 2) gene rearrangements.

Conclusion : Knowledge of the cytological characteristics of Warthin tumors with mucous metaplastic cells resembling low-grade MEC enables accurate diagnosis of these salivary gland tumors.