Solitary fibrous tumor (SFT) is usually an indolent neoplasm with a low rate of local recurrence and metastasis. Although dedifferentiation of low-grade sarcoma is well documented, the concept of dedifferentiated SFT was not recognized until recently. A case of intracranial SFT with seven recurrences within 5 years, showing progression and dedifferentiation during the course of disease, is reported here. A 51-year-old woman with a history of irradiation during infancy presented with a SFT in the right posterior fossa. Because of the close proximity to the brain stem, the tumor could not be removed completely. The tumor recurred 12, 16, and 28 months after the initial operation. With the repeated recurrences, cellularity, mitotic count, and Ki-67 (MIB-1) index increased gradually. The histology suddenly changed at the fourth recurrence, which occurred 16 months after postoperative radiation therapy for the third recurrence. The tumor revealed a fibrosarcoma-like appearance with necrosis and markedly increased mitotic activity. The tumor further recurred 50, 52, and 55 months after the initial operation with the same fibrosarcoma-like histology. The patient died of uncontrolled tumor 58 months after the initial operation. In this case radiation may have played some role in the tumorigenesis, progression, and dedifferentiation of the SFT.

Endometrial polyps are very common benign endometrial lesions, but their pathogenesis is poorly understood, except for a few studies indicating the possibility of benign stromal neoplasm. Although the histopathological diagnosis of endometrial polyp on a surgical specimen is straightforward, it is often difficult to differentiate endometrial polyp from endometrial hyperplasia on a biopsy or curettage specimen. Presently, there is no immunohistochemical marker helpful in this differential diagnosis. In this study, we examined p16 expression in 35 endometrial polyps and 33 cases of endometrial hyperplasia that included 16 simple hyperplasias, 14 complex atypical hyperplasias, and 3 complex hyperplasias without atypia. Stromal p16 expression differed significantly between the two groups; it was seen in 31 (89 %) endometrial polyps, but in only 1 (3 %) endometrial hyperplasia. The percentage of p16-positive stromal cells ranged from 10 to 90 % (mean, 47 %) and the positive cells tended to be distributed around glands. Six cases of endometrial hyperplasia within an endometrial polyp were also examined and all cases showed stromal p16 expression. There was no difference in glandular p16 expression between endometrial polyps 33 (94 %) and hyperplasia 27 (82 %). The p16-immunoreactivity was mostly confined to metaplastic epithelial cells in both groups. Stromal p16 expression might be a peculiar characteristic of endometrial polyp and constitute a useful marker for the diagnosis, especially in fragmented specimens from biopsy or curettage. Stromal p16 expression might be a reflection of p16-induced cellular senescence, which has been documented in several benign mesenchymal neoplasms.

Our results suggest that CAFs promote lung cancer progression partly through the direct regulation of gene expression in the LCs of invasive cancer nests.

Pathology (-xxxx) xxx(xxx), xxx Please cite this article as: Sasaki E et al., Sialadenoma papilliferum of the bronchus: focus on histological and genetic distinction from mixed squamous cell and glandular papilloma, Pathology,

The RET finger protein (RFP) is a transcription factor belonging to the TRIM (tripartite motif) superfamily of proteins. RFP is expressed in a variety of human and rodent tumor cell lines and in several kinds of human cancer. Expression of RFP is associated with prognosis of colon and endometrial cancers. In the present study, we evaluated the expression of RFP in lung cancer and assessed its clinical significance. Tissue microarrays were constructed from 108 cases of lung cancer, and the sections were analyzed for RFP expression by immunohistochemistry. RFP expression was detected in the nucleus in 66.7% of lung cancer tissues examined. RFP expression was statistically significantly associated with thyroid transcription factor 1 (TTF-1) expression (P= 0.028). However, no significant association was observed between RFP expression and other clinicopathological or genetic factors, including epidermal growth factor receptor (EGFR) mutations. Interestingly, we found that RFP expression correlated with poor prognosis in patients with EGFR mutations (P= 0.032). Our results suggest that RFP has a role in mutated EGFR signaling and that RFP status may be a prognostic factor for lung cancer with EGFR mutations.