International Journal of Gynecological Pathology 29:189–192, Lippincott Williams & Wilkins, Baltimore r 2010 International Society of Gynecological Pathologists Case Report Solitary Fibrous Tumor of the Uterine Cervix Kurosh Rahimi, M.D., M.Sc., F.R.C.P.C., Patricia A. Shaw, M.D., F.R.C.P.C., and Runjan Chetty, M.B.B.Ch., F.R.C.Path., F.R.C.P.C., Dphil. Summary: A 68-year-old woman with stage pT1b1 N0 cervical squamous carcinoma had an incidental cervical polyp. The polyp measured 1.7 cm in maximal diameter and histologic evaluation showed it to be composed of spindle-shaped cells with hypercellular and hypocellular foci. The stroma was collagenized and contained several dilated vascular channels that imparted a hemangiopericytic pattern to the lesion. Immunohistochemistry showed the spindle cells to be positive for vimentin, CD99, CD34, bcl-2, ER, PR, and b-catenin (cytoplasmic) but negative for EMA, S100, factor XIIIa, AE1/AE3, caldesmon, desmin, CD31, and smooth muscle actin. The morpho- logy and immunophenotype was in keeping with a diagnosis of a solitary fibrous tumor (SFT). SFT shares several histologic features of a superficial cervicovaginal myofibro- blastoma; the cellular variability, pattern and distribution of vessels, stromal collageni- zation, and desmin negativity favors SFT. Key Words: Uterine cervix—Solitary fibrous tumor—CD34—Mesenchymal tumor. Solitary fibrous tumor (SFT) is an uncommon tumor that occurs mainly in the pleura but has also been documented to involve a wide range of extrapleural sites such as mediastinum, lung, breast, oropharynx, sinonasal, liver, pancreas, thyroid, spinal cord, meninges, and orbit (1–4). In 1931, Klemperer and Rabin (5) first described this tumor as a benign variant of mesothelioma. SFT in the female genital tract is extremely rare, and to the best of our knowledge 11 cases have been reported in various sites within the female genital tract: vulva (1,6,7), vagina, (4,8,9), para-vaginal space (2,3), uterine cervix with extension to vaginal wall (2,3), uterus (10), paraovarian tissue (11), broad liga- ment of the uterus (12), and fallopian tube (13). Uterine cervix SFT is particularly rare, with only 1 case reported earlier in a 78-year-old woman. Herein we present the second case of SFT arising in the cervix and causing a polypoid lesion. The purposes of this study are to highlight the occurrence of SFT in an unusual location, discuss the differential diagnosis, and suggest immunohistochemical and histologic features that help separate this lesion from the more common mesenchymal lesions of the cervix, in particular from superficial cervico-vaginal myo- fibroblastoma. CASE REPORT The patient was a 68-year-old woman (G7 P6) with 1 miscarriage who was referred to our institution for squamous cell carcinoma of the uterine cervix. She had no clinically significant family history and no past medical or surgical history of note. A high-grade squamous intraepithelial lesion was first diagnosed on routine Pap smear in June 2008. The patient was lost to follow-up and in February 2009, a new Pap smear, cervical biopsy, and endo- cervical curetting led to diagnosis of invasive squa- mous cell carcinoma. 189 DOI: 10.1097/PGP.0b013e3181b91a6d From the Department of Pathology Laboratory Medicine Programme, University Health Network/University of Toronto, Toronto, Canada. Address correspondence and reprint requests to Dr. Kurosh Rahimi, MD, MSc, FRCPC, Department of Pathology, Laboratory Medicine Programme, University Health Network, The Toronto General Hospital, 200 Elizabeth Street, 11th Floor, Eaton Wing, Toronto, Ontario, Canada M5G 2C4. E-mail: Kurosh.Rahimi@ mail.mcgill.ca.