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Other Rare Mesenchymal Tumors and Sarcomas

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Tumors with Neural Differentiation

  • May occur in patients with neurofibromatosis I (von Recklinghausen disease) and probably arise from the adjacent pelvic autonomic plexus.
  • Mostly are young patients (1 month to 35 years old) and had neurofibromas in other organs including the skin.
  • Present as mass lesion or with obstructive symptoms.
  • Most prostate neurofibromas also involved the bladder.
  • Morphology of prostatic neural tumors (neurofibroma or schwannoma) are similar to those in somatic tissues (image A) and can be confirmed by S100+.

Vascular Tumors

  • Hemangiomas may arise along the posterior urethra; very rare within the prostate.
  • May cause hematuria, hematospermia and/or post ejaculation hematuria.
  • Posterior urethral hemangiomas are seen in patients 29-80 years old (mean 57) and cystoscopically, appear as small sessile varicosities between the verumontanum and external sphincter.
  • Histologically, majority are cavernous hemangioma.
  • Prostatic angiosarcoma (AS) is also rare and consists of proliferating vascular channels lined by atypical spindle to epithelioid cells (image B).
  • Diagnosis of AS is confirmed by endothelial markers such as factor VIII-related antigen, CD34+ or CD31+.
  • Other rare sarcomas reported in the prostate include synovial sarcoma (with t(X;18)(p11.2;q11.2) or SYT-SSX fusion), primitive neuroectodermal tumor (PNET) (with t(11;22)(q23;q12) PNET or EWS/FLI1 transcript) and malignant fibrous histiocytoma (MFH).