Diagnostic Workup of Primary Adrenal High-Grade Undifferentiated Pleomorphic Sarcoma Initially Presenting as Brain Metastasis.

Primary adrenal high-grade undifferentiated pleomorphic sarcoma (UPS) is an exceptionally rare malignant mesenchymal neoplasm, and presentation with brain metastasis as the initial manifestation is even more uncommon. This report highlights the diagnostic evaluation and multidisciplinary management of a patient presenting with an undifferentiated brain metastasis accompanied by an adrenal mass. A 75-year-old woman presented with speech disturbance, cognitive slowing, memory decline, gait instability, and right-sided weakness. Brain computed tomography and contrast-enhanced magnetic resonance imaging revealed a left frontal lesion with multiple intracerebral nodules. Positron emission tomography/computed tomography further demonstrated a left adrenal lesion and additional metastatic foci. Owing to symptomatic mass effect, the brain lesion was surgically resected. Initial pathology suggested a poorly differentiated malignant tumor, and the tumor origin remained uncertain after the first immunohistochemical assessment. Subsequent multidisciplinary review, serial adrenal imaging, adrenal core needle biopsy, and comparative pathologic evaluation progressively redirected the diagnosis toward a high-grade undifferentiated sarcoma, morphologically consistent with UPS. The patient subsequently received postoperative brain radiotherapy, anthracycline-based chemotherapy, additional systemic therapy, and local treatment for progressive metastatic disease. Despite multimodal management, the tumor rapidly progressed with thigh metastasis, bilateral adrenal involvement, skeletal dissemination, and bilateral pathologic femoral fractures. The patient ultimately died of intracerebral hemorrhage. This case expands the clinical spectrum of primary adrenal UPS and underscores the importance of dynamic diagnostic reassessment, multisite tissue sampling, extended immunohistochemical evaluation, and multidisciplinary collaboration when evaluating undifferentiated brain metastases associated with an adrenal mass.