Abstract
Prostate adenocarcinoma most commonly metastasizes to bone and lymph nodes; isolated soft-tissue presacral metastasis without a known primary is exceedingly rare and poorly characterized. We report a 69-year-old man presenting with hematuria and an incidental 4-cm presacral mass. MRI demonstrated a solid, heterogeneously enhancing lesion within the right mesorectal compartment without intraluminal involvement, most consistent with a primary neurogenic tumor. Serum PSA was not obtained preoperatively, as symptoms were attributed to chronic suprapubic catheter irritation and imaging did not suggest a prostatic origin. Preoperative biopsy was not pursued given the lesion’s deep posterior location at the S4 level—proximity to sacral nerve roots precluded safe percutaneous access, and transrectal biopsy is contraindicated. The mass was resected via a posterior transsacral (Kraske) approach for presumed primary presacral neoplasm. Histopathology revealed metastatic prostatic adenocarcinoma with positive PSA and prostatic acid phosphatase immunostaining, identifying an occult primary tumor. This case illustrates an atypical diagnostic scenario in which resection was undertaken for a presumed primary lesion; the metastatic diagnosis was an unexpected pathologic finding that would have substantially altered management had it been established preoperatively. This case underscores the importance of including serum PSA in the standard workup of solid presacral masses in older male patients and demonstrates that the Kraske approach can provide adequate exposure for selected posteriorly situated extrarectal masses when diagnosis remains uncertain and resection is clinically indicated.
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