Aims: To determine the clinicopathological features of pulmonary sclerosing pneumocytoma (PSP) with spindle cells and in cases with positive detection of PSP cells in the lymph nodes. Methods and results: This article report the clinical, histological and immunohistochemical features of PSP with dense spindle stromal cells in five patients (including one case with lymph node metastasis) and PSP accompanied by positive nodes in two patients out of 239 cases diagnosed at our institution between 2007 and 2019. The literature on PSP was also reviewed in detail. Six patients were female, and one (with a positive node) was male; their average age was 53 years. Thoracic imaging revealed solid tumours with clear borders and a uniform texture in six patients, but one patient had a lobulated tumour with uneven densities. All tumours were unifocal, and they had an average size of 31 mm. Tumours from five cases were mainly composed of solid regions of diffuse spindle cells rather than polygonal cells. Immunohistochemical staining demonstrated that thyroid transcription factor-1, vimentin, epithelial membrane antigen (weak) and oestrogen receptor (partial) were expressed in spindle cells. The average follow-up time was 31 months. Two of the 234 PSP cases for which adequate data were available had positive nodes (metastasis rate: 0.8%), and one of the five patients with PSP with spindle cells showed lymph node metastasis (metastasis rate: 20%). In addition, stromal cells were found to be predominant at metastatic sites. Conclusions: Spindle cells are present among the stromal cells of PSP, and not all of them are round cells. PSP patients with spindle cells or male patients may be more prone to metastasis than others.

Purpose Solitary fibrous tumor (SFT) is a spindle cell neoplasm that rarely occurs in orbit. This study aimed to report clinical, imaging, and pathological features of three patients with recurrent orbital SFTs.Methods Clinical, imaging, and pathological data of the three patients were retrospectively reviewed, and the results were compared with those of previously reported cases with recurrent orbital SFT. Results One female and two male patients (mean age, 54 years old) were included in this study. The present cases and literature review showed that the average time to recurrence in patients who aged under 50 years old was shorter than that in those who aged over 50 years old. The most common site for recurrent orbital SFT was the retrobulbar area of the orbit (23.8%). Imaging examinations showed consistent intensity of MRI signals before and after recurrence. Immunohistochemical results of all cases revealed the expressions of CD34. The mitotic rate increased in 4/8 cases, and the percentage of Ki-67-positive cells was elevated in 5/16 cases. Conclusion These results suggested that young patients were more likely subjected to recurrent orbital SFT. The postoperative pathological diagnosis revealed that patients with recurrent orbital SFT had more nuclear abnormalities and mitotic activity, as well as a higher percentage of Ki-67-positive cells, indicating that orbital recurrent SFT tended to be malignant according to both morphological features and immunohistochemistry results.