S103 Am J Clin Pathol 2018;149:S90-S128 DOI: 10.1093/AJCP/AQX123 © American Society for Clinical Pathology AJCP / Meeting AbstrActs 241 Coexistence of Immunochemical Features of Usual Type and Differentiated Type Vulvar Intraepithelial Neoplasia—A Rare Case Report Yiqin Xiong, Ashraf Khan, MD, FRC, Hongwei Bai, MD, PhD; University of Massachusetts, Amherst Objectives: Current classifcation of squamous cell car- cinoma precursors includes two distinct categories: HPV-dependent low-grade or high-grade squamous intraepithelial lesions (LGSIL, HGSIL) and HPV- independent TP53-associated differentiated type VIN (dVIN). Distinguishing between these two is important because the risk of progression to invasion can be rapid in dVIN. Methods: A 64-year-old woman presented with a right vul- var lesion for presurgical consultation in our institution. Her previous biopsy at another hospital was diagnosed as dVIN based on the morphology, patchy p16 and weak p53 staining. Right vulvar excision and immunochemical analyses were performed. Results: Sections show areas of irregular elongation and anastomoses of the rete ridges, basal and parabasal keratinocytic atypia with terminal differentiation but with areas of abnormal keratinization. The overlying hyperkeratosis and a background of lichen sclerosus are present. Immunostains for p53, p16, and Ki67 were per- formed, which showed an unequivocal evidence of mostly parabasal nuclear p53 positivity, with elevated Ki67- labeling index. The fndings are highly suggestive of dVIN. However, a “block-type,” strong and diffuse nuclear and cytoplasmic p16 positivity is present on p16 immunostain in the lesional cells. Molecular tests for high-risk HPV were performed and showed negative results for a selected panel. Although the treatment for both entities is wide local excision, the unique staining results on p53 and p16 in this vulvar lesion posed a challenge in the diagnosis. Conclusion: This is a rare case showing both typical immu- nochemical features for two distinct entities in vulvar pre- cancerous lesions. This suggests (1) diffuse and strong with a “block-type” positivity of p16 is probably not suf fcient to rule out dVIN; or (2) there is a possibility of unusual high-risk HPV infection associated with TP53 mutation in this patient. These two events might not be mutually exclu- sive of tumorigenesis of vulvar intraepithelial neoplasia. 242 A Rare Case of Ovarian Serous Borderline Tumor With Brain Metastasis Sonia Veran-Taguibao, MD, Roberto Alvaro Taguibao, MD, Ted Farzaneh, MD, Di Lu; University of California, Irvine School of Medicine, Irvine Serous borderline tumor (SBT) represents a group of noninvasive tumor of ovary bridging between benign ade- noma and invasive carcinoma. They are commonly seen in younger women and have excellent outcome, except occa- sional local recurrence. Metastasis to the lymph nodes has rarely occurred. So far, the only distant metastases reported were to the supraclavicular and internal mam- mary lymph node. Here, we present a 33-year-old nullipa- rous woman diagnosed with Stage IV-B serous borderline tumor to the brain. Her serous borderline tumor with 1 mm focus of microstromal invasion of left ovary eight years ago, with a recurrent tumor of the right ovary occurred 4 years ago, for which she underwent two unilat- eral salpingo-oophorectomies with omentectomy on sep- arate occasions with extensive abdominal, peritoneal, and pelvic lymph node biopsies. No evidence of extraovarian spread on both times was identifed. However, 4 years after her last surgery, the patient presented to our insti- tution with a migraine. MRI revealed four supratentorial lesions with two dominant proteinaceous mass lesions (6.0 x 4.5 x 3.5 cm and 4.5 x 3.5 x 2.8 cm) having irregular lobulations in the bilateral temporal lobes consistent with metastatic disease. Biopsy of the dominant lesion shows clusters of broad papillae with hierarchical branching lined by polygonal to columnar serous epithelium with mild to moderate atypia. Findings are consistent with metastatic serous borderline tumor. To our best knowl- edge, this is the frst case reported of a serous borderline tumor with metastasis to the brain. No current review or literature supports this distant metastasis. 243 Solitary Fibrous Tumor/Hemangiopericytoma: A Case Report Christian Salib, MD, Alexandra Budhai, MD, George Kleinman, MD; Westchester Medical Center/New York Medical College, Valhalla, NY Solitary fbrous tumor/hemangiopericytoma is an increasingly recognized, combined term describing a spectrum of rare mesenchymal tumors. The term was introduced in the 2016 World Health Organization clas- sifcation of tumors of the central nervous system follow- ing the discovery of a shared inversion at 12q13 between solitary fbrous tumors and hemangiopericytomas. This genomic alteration results in a NAB2/STAT6 gene fusion with resultant STAT6 nuclear expression. The resultant STAT6 immunopositivity is now necessary for diagno- sis. While most commonly described in the pleura, orbit continues to be an uncommon extrapleural sites. Here, we present a case of a previously healthy 50-year-old man who presented with headache, dizziness, and a right CN IV palsy. MRI of the orbits demonstrated a large, enhanc- ing, extra-axial mass within the right middle cranial fossa Downloaded from https://academic.oup.com/ajcp/article-abstract/149/suppl_1/S103/4801534 by guest on 19 July 2020