Non-neoplastic tumour associated cysts

Non-neoplastic tumour associated cysts (TACs) are benign fluid-containing cysts adjacent to, but not within, a neoplasm.

TACs are most likely represent trapped encysted pools of CSF adjacent to large extra-axial neoplasms, when the tumor grows it traps the CSF between it and the adjacent brain. It is considered a tumour "epiphenomenon".

  • smooth well demarcated cyst
  • extra-axial TACs are more common than intra-axial, e.g. meningioma, craniopharyngioma, vestibular schwannoma
  • can be single or multiple
  • it abuts the tumor directly
  • vary from small to very large size
  • enhancement: absent or minimal
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Article information

rID: 42414
Section: Pathology
Synonyms or Alternate Spellings:
  • Tumor associated arachnoid cyst
  • Tumor associated enlarged perivascular space
  • Herald cyst
  • Peritumoral cyst
  • Non-neoplastic tumor-associated cysts (TACs)

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Cases and figures

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    Case 1: TAC adjacent to meningoma
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