507 Mature Cystic Teratoma involved by Myeloid Sarcoma: A Rare Case Presentation

Abstract Introduction/Objective The simultaneous occurrence of mature cystic teratoma (MCT) and myeloid sarcoma (MS) poses a significant diagnostic challenge. We present a case illustrating the clinical and diagnostic aspects of this unusual presentation. Methods/Case Report A 72-year-old female with a medical history of diabetes presented for generalized weakness following a fall. Work-up revealed leukocytosis, an umbilical hernia, as well as a large adnexal pelvic mass with calcifications. She underwent surgical repair of the hernia with omental biopsy and left salpingo-oophorectomy. Histologic examination revealed involvement of diffuse sheets of atypical blastic cells with high mitotic activity in the hernia sac, omentum, and pelvic mass. Immunohistochemistry demonstrated positivity for CD34, CD68, CD138, and Cyclin-D1, with a Ki-67 proliferation index of 70%. A broad panel of other hematologic, epithelial, and neuroendocrine markers was negative. The mass was identified as a MCT with ectodermal and mesodermal elements. Findings supported a diagnosis of MS involving an MCT. Despite intervention, the patient’s condition deteriorated, and she passed away two days postoperatively. Results NA Conclusion This case highlights a rare coexistence of MCT and MS. Immunohistochemistry played a pivotal role in establishing the diagnosis. Clinicians should maintain a high index of suspicion in such complex cases to guide timely and appropriate management.