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Case of the Month: May 2022

posted: May 24, 2022

This is a 43-year-old female with history of serous borderline tumor (SBT) of the right ovary with ovarian surface involvement and positive pelvic washing, without non-invasive or invasive implant, status post right oophorectomy in 2015 (pT1cNx), presents with right pleural effusion. Pleural effusion ThinPrep and cell block are shown below.

  • Pleural Effusion ThinPrep (Papanicolaou Stain) and Cell Block (H&E Stain)
  • BerEP4
  • PAX8
  • ER
  • P53
  • P16
  • Ki67

Additional immunostains results: MOC31 is positive; PR, GATA3, and TTF1/Napsin are negative.

Final Diagnosis: Neoplastic Cells Present. Low Grade Serous Neoplasm.
The specimen is composed of low-grade neoplastic cells arranged in papillary structures with relatively uniform small cells, increased N/C ratio, and mild nuclear atypia. Immunostains show the neoplastic cells to be positive for BerEP4, MOC31, PAX8, and ER, but negative for p53 (wild type with patchy and weak nuclear expression), p16 (mosaic pattern with patchy and weak nuclear/cytoplasmic expression), PR, GATA3, and TTF1/Napsin (dual stain). Ki67 shows a low proliferation index (<1%). Given the patient’s history of serous borderline tumor of the ovary, the cytomorphology and immunoprofile are compatible with metastatic low grade serous neoplasm involving pleural fluid. Molecular testing for KRAS and BRAF was not performed due to scant material on the cell block; malignant transformation to low-grade serous carcinoma (LGSC) cannot be excluded.
SBT is a non-invasive, low grade, proliferative epithelial neoplasm. A reported 4-7% of women with SBT develop subsequent carcinoma, usually low-grade. Ovarian surface involvement is a risk factor for subsequent development of carcinoma. SBT may rarely metastasize, with nodal and brain metastases reported in the literature. On the basis of cytologic features and/or immunocytochemistry alone, SBT cannot be distinguished from LGSC.
  1. WHO Classifications of Tumors: Female Genital Tumors. 5th Edition, 2020
  2. Veran-Taguibao, S, Taguibao RA, Gallegos N, et al. A rare case of ovarian serous borderline tumor with brain metastasis. Case Rep Pathol. 2019: 2954373.
  3. Siemon J, Nguyen DM, Pinto A, et al. Rare metastatic patterns after malignant transformation of serous borderline tumor of the ovary. J Surg Oncol. 2019; 119 (6): 814-816.

This case is contributed by Qun Wang, MD, PhD, Department of Pathology and Laboratory, Emory University Hospital.