Placental site nodule

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Placental site nodule, abbreviated PSN, is a benign remnant of a placenta. It is seen on endometrial biopsies and hysterectomy specimens.

Placental site nodule
Diagnosis in short

Placental site nodule. H&E stain.

LM paucicellular hyaline material scattered cells (variable cell population: small to large cells with clear to eosinophilic cytoplasm), +/-multinucleation, no mitotic activity
LM DDx invasive cervical squamous cell carcinoma, exaggerated placental site, fibrin +/-inflammatory cells
Site endometrium

Clinical history previously pregnant
Symptoms none
Prevalence common
Prognosis benign
Treatment none

Implantation site redirects here.

General

  • Benign.
  • Intermediate trophoblast remnants from a previous gestation.[1]
  • Usually an incidental finding.

Clinical:

  • Usually asymptomatic.
  • Vaginal bleeding. (?)
  • Infertility. (?)

Microscopic

Features:[1]

  • Paucicellular with hyaline material scattered cells.
  • Variable cell population:
    • Small-large cells.
    • Clear to eosinophilic cytoplasm.
    • +/-Multinucleation.

Notes:

  • No mitotic activity.

DDx:

  • Invasive (cervical) squamous cell carcinoma.
    • Can be sorted-out with IHC (SCC will typically be: p16 +ve, MIB1 +ve).
  • Exaggerated placental site.
    • Different histomorphology than PSN; EPS:[1] syncytiotrophoblastic tissue, in cords/nests, no hyaline nodules.
  • Fibrin +/-inflammatory cells.

Images

Case 1

Case 2

www

IHC

Features:[1]

  • Inhibin alpha +ve.
  • CK18 +ve.
  • MIB1 low.

Other:

  • p16 -ve.

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- CONSISTENT WITH MENSTRUAL ENDOMETRIUM (FRAGMENTED ENDOMETRIUM WITH SIMPLE
  GLANDS WITH APOPTOTIC CELLS, ABUNDANT NEUTROPHILS, CONDENSED ENDOMETRIAL STROMA
  (FOCAL) AND BLOOD).
- PLACENTAL SITE NODULE AND DECIDUA.
- NEGATIVE FOR HYPERPLASIA AND NEGATIVE FOR MALIGNANCY.
ENDOMETRIUM, BIOPSY:
- PROLIFERATIVE PHASE ENDOMETRIUM.
- BENIGN PLACENTAL SITE NODULE, SMALL.
- NEGATIVE FOR HYPERPLASIA.

See also

References