case_images: PMC10867882_01
case_images: (A-B) CT abdomen/pelvis with contrast. Complex, heterogeneous, encapsulated solid mass (red arrow) within the pelvis measuring up to 16.4 cm. Markedly enlarged, heterogeneous, and infiltrative prostate gland (blue arrow), which obliterates the seminal vesicles and invades the urinary bladder in keeping with advanced prostate carcinoma.
case_images: cureus-0016-00000052356-i01.jpg
case_images: PMC10867882_01_cureus-0016-00000052356-i01.jpg
case_images: FIG1
case_images: Further radiological evaluation with CT abdomen/pelvis with contrast revealed peritoneal carcinomatosis and a complex pelvic mass measuring 15 x 10 cm causing deviation of the rectum and bladder (Figure 1).
case_images: (A) Hematoxylin and eosin (H&E) (200X magnification) of the abdominal soft tissue biopsy showing poorly formed glands. (B) The glands are positive for NKX3.1 consistent with metastatic prostate adenocarcinoma. (C) H&E (200X magnification) of the pelvic mass biopsy consists of bland-appearing spindle cells. (D) The spindle cells are positive for S100.
case_images: cureus-0016-00000052356-i02.jpg
case_images: PMC10867882_01_cureus-0016-00000052356-i02.jpg
case_images: FIG2
case_images: The biopsy of the abdominal soft tissue was positive for metastatic prostate adenocarcinoma (Figure 2A-2B). HMB45 (Figure 2C-2D).
case_images: (A) Hematoxylin and eosin (H&E) (20X magnification) of the resection specimen shows a variegated appearance with alternating areas of high cellularity (Antoni A) and low cellularity (Antoni B). (B) H&E (200X magnification) shows fascicles of uniform spindle cells with fibrillary eosinophilic cytoplasm, the cells lack significant pleomorphism. (C-D) S100 and SOX10 IHC highlight positive Schwann cells, respectively. (E-F) The tumor cells are negative for HMB45 and NKX3.1, respectively.
case_images: cureus-0016-00000052356-i03.jpg
case_images: PMC10867882_01_cureus-0016-00000052356-i03.jpg
case_images: FIG3
case_images: Histopathologic examination was consistent with schwannoma (Figure 3A-3B], as indicated by positive immunostains for S100 and SOX10 (Figure 3C-3D), while negative for cytokeratin AE1/AE3, melanocytic markers HMB45 and MelanA (Figure 3E). NKX3.1 and PSA were also negative; helping rule out prostate origin (Figure 3F).