Unusual pineal gland lesion presenting with obstructive hydrocephalus: A multimodal imaging perspective

Metastatic melanoma to the pineal gland is exceedingly rare, with only a few cases documented in the literature. We report a 41-year-old male who presented with progressive headaches, nausea, vomiting, and altered mental status, ultimately found to have obstructive hydrocephalus secondary to a hypermetabolic pineal mass. Imaging revealed a well-circumscribed lesion on positron emission tomography/computed tomography (standardized uptake value [SUV] of 17.6) and magnetic resonance imaging findings consistent with cerebrospinal fluid obstruction. Further evaluation identified additional metastatic sites, including a left upper quadrant skin lesion. Histopathologic examination confirmed metastatic melanoma with a primary cutaneous origin. Despite undergoing whole-brain radiation therapy and systemic immunotherapy, the patient’s neurological condition deteriorated due to progressive central nervous system disease. This case underscores the critical role of advanced imaging techniques in identifying atypical metastatic sites and highlights the challenges in managing rare intracranial melanoma metastases.