Neurothekeoma

Neurothekeoma is a benign peripheral nerve sheath tumour.

It is also known as myxoma of the nerve sheath and nerve sheath myxoma.

There is growing evidence that neurothekomas and dermal nerve sheath myxomas are distinct entities.

General

• Rare.
• Female > male.

Microscopic

Features:

• Superficial dermal lesion:
  • Usu. lobulated or micronodular architecture - key feature.
    • +/-Focal sheeting.
  • Spindle/epithelioid morphology with pale eosinophilic cytoplasm - key feature.
  • +/-Inflammation around lesion.
  • +/-Surrounded by collagen.

Notes:

• No atypia.
• Mitoses rare/none.
• Often poorly circumscribed.

Subtypes:

• Cellular.
• Myxoid.
• Intermediate.

DDx:

• Dermatofibroma.
• Angiomatoid fibrous histiocytoma -- have cystic blood filled spaces, inflammation.

Images:

• Neurothekeoma (WP).
• Neurothekeoma - several images (upmc.edu).
• Nerve sheath myxoma (dermpedia)]

IHC

Features:

• NKI/C3 (AKA NKI-C3) +ve.
• NSE +/-ve.

Others:

• Vimentin +ve.
• CD10 +ve.
• Microphthalmia transcription factor +ve.
• PGP9.5 +ve.

Exclusionary:

• S100 -ve.
  • Exclude other peripheral nerve sheath tumours. (???)
  • Myxoid variant +ve. ^{[citation needed]}

See also

• Peripheral nerve sheath tumours.