Diffuse Ectopic Deciduosis Mimicking as Peritoneal Carcinomatosis: A Case Report of a Young Female with Multiple Serosal and Omental Nodules Found During a Caesarian Section

Abstract

Background & Objectives: Ectopic deciduosis refers to an abnormal occurrence of decidual tissue beyond the

endometrium, predominantly on the surface of the uterus, fallopian tubes, ovaries and omentum. Diffuse

omental and perito-neal involvement is a perplexing manifestation that may mimic peritoneal carcinomatosis. It

is not accompanied by any symptoms and complications in most of the cases and does not require treatment.

However, rarely it can present with acute abdomen or imitate peritoneal malignancy and, thus, associated with

diagnostic difficulties and unnecessary interventions. Aim of this case report is to describe a rare case of

peritoneal deciduosis in a young female, found incidentally, during a caesarean section, mimicking metastatic

nodules. A futile hysterec-tomy along with omentectomy was performed.

Methods: A case of diffuse ectopic deciduosis mimicking as peritoneal carcinomatosis in a 29 years young

female with full term pregnancy was found during a lower segment caesarian section, undertaken in a tertiary

care teaching hospital of Lahore, Pakistan. The histopathological diagnosis was based on common technique

of paraffin embedding and hematoxylin-eosin staining along with ancillary immune-histochemical

evaluation.

Results: Histopathological evaluation showed ectopic decidual tissue consisted of solid nests and loosely

cohesive aggregates; large polygonal cells with abundant granular eosinophilic cytoplasm; sharply defined

cell borders, bland nuclei with dispersed chromatin and single conspicuous nucleoli on the surface of uterus

and in omental fat. Weak staining for CD30 was observed in the decidual cell cytoplasm and negative staining

for CK and Calretinin in decidual cells was found. Calretinin and CK highlight benign mesothelial cells and

help to rule out differentials of mesothelioma and metastatic carcinoma.

Conclusion: Peritoneal deciduosis represents a rare entity and it is important to consider this condition in

patients, especially in pregnant women, to prevent unnecessary intervention In addition, distinguishing this

condition from malignant neoplasms will help in deciding correct treatment options.