96 Prostatic Stromal Tumor of Uncertain Malignant Potential Masquerading as a Teratoma on Radiologic Imaging

This is the authors' abstract. We don't add key points for this paper.

Introduction/Objective Prostatic stromal tumors, including stromal sarcoma and stromal tumor of uncertain malignant potential (PSTUMP), represent less than 1% of primary prostatic neoplasms and typically occur in middle-aged to older adults. Their morphologic spectrum—including myxoid, spindled, round cell, and phyllodes-like patterns—can complicate diagnosis on limited biopsy. PSTUMP is particularly challenging due to its unpredictable behavior and potential for recurrence or progression. We present a rare case of PSTUMP initially suspected radiographically to represent a mature teratoma. Methods/Case Report A 19-year-old male presented with chest discomfort, palpitations, and abdominal pain. Imaging revealed a 3.4-cm well-circumscribed mass arising from the right posterolateral prostate, abutting the rectum and seminal vesicle. MRI showed an encapsulated lesion with internal fat signal and focal enhancement, raising suspicion for teratoma. Biopsy demonstrated myxoid stromal proliferation with focal phyllodes-like architecture. Immunohistochemistry showed SMA positivity and negativity for desmin, myogenin, CD34, and STAT6. Robotic excision revealed a 3.6-cm encapsulated multiloculated cystic mass with papillary excrescences and phyllodes-like stromal overgrowth without atypia, necrosis, or increased mitoses. Margins were negative. Findings supported PSTUMP. Results NA Conclusion This case highlights the diagnostic challenges of PSTUMP, particularly in young patients and when radiologic features mimic teratoma. Awareness of its morphologic spectrum is essential to avoid misclassification.