Atypical new-onset ascites due to a rare variant of cecal carcinoma in a patient with a ventriculoperitoneal shunt: A case report

Introduction

Malignancy-associated ascites (MAA) is the second cause of new-onset ascites after cirrhosis with portal hypertension (PHT), and is usually related to peritoneal carcinomatosis. Ascitic fluid is an exudate, with low serum-ascites albumin gradient (SAAG), ≥ 500 lymphocytes/mm³ and positive cytology. However, MAA may show atypical patterns. Signet ring cell carcinoma (SRCC) is a poor prognosis adenocarcinoma subtype with special clinical and endoscopic presentation.

Case summary

A 68-year-old female, without relevant medical history, with a ventriculoperitoneal shunt (VPS), presented a 1-week increase of abdominal perimeter, loose stools, hyporexia, and fever. In repeated paracentesis, ascites showed transudate properties, high SAAG, low cellularity, negative cultures, and cytologies. She didn’t have neurological impairments nor VPS dysfunctions. Significant PHT and other ascites etiologies were excluded. Ascites persisted despite evacuation paracentesis and diuretics. Further diagnostic workup finally revealed peritoneal carcinomatosis probably originated in a cecal SRCC.

Conclusions

We report an atypical presentation of MAA (transudative ascites, SAAG suggesting PHT, low cellularity, and initially negative cytology) due to a rare adenocarcinoma subtype, representing a challenge regarding its unusual characteristics and difficulties to reach a final diagnosis.