Villitis of unknown etiology

Villitis of unknown etiology
Diagnosis in short
Villitis of unknown etiology. H&E stain.
LM	lymphocytes in the villous stroma, no neutrophils, no significant plasma cells
LM DDx	acute villitis
IHC	lymphocytes predominantly CD8 +ve
Site	placenta
Associated Dx	IUGR, recurrent pregnancy loss
Clinical history	+/-previous pregnancy loss
Prevalence	uncommon

Villitis of unknown etiology, abbreviated VUE, is rare recurrent pathology of the placenta.

General

Features:

• Usually term placenta.
• Prevalence: 5% to 15% of all placentas.
• Associated with:
  • Intrauterine growth restriction (IUGR).
  • Recurrent reproductive loss/adverse outcomes in subsequent pregnancies -- key point.
    • Recurrence in up 37% of cases.

Etiology:

• Unknown - as the name of the entity suggests.
  • Suspected to be immune-mediated.

Microscopic

Features:

• Lymphocytes in villous stroma - key feature.
  • Usually focal/patchy.
  • Lymphocytes: maternal derivation, T-lymphocytes -- mostly CD8-positive.
• +/-Intervillositis (lymphocytes between villi).
• +/-Histiocytes.

Notes:

• Lymphocytes are smaller and stain darker than the cells of the villi. (???)
• Neutrophils are usually absent. A significant number of 'em is suggestive of an infectious villitis.
• Infective villitis is usu. B-cell predominant.
• No plasma cells - this suggests an infectious etiology.
  • Rare plasma cells may be seen in the decidua -- these can be ignored.

Images

• 

  VUE - intermed. mag. (WC)

• 

  VUE - very high mag. (WC)

www:

• VUE (bmj.com).
  • VUE (flickr.com).
• VUE (flickr.com).

See also

• Acute villitis.
• TORCH infection.
• Placenta.