# A Unique Case of Intra-Abdominal Diffuse Lymphangiomatosis Mimicking a Pseudomyxoma Peritonei

## TL;DR

A rare case of intra-abdominal lymphangiomatosis was misdiagnosed as pseudomyxoma peritonei and successfully treated with surgery.

## Contribution

This case highlights the rarity and diagnostic challenge of diffuse intra-abdominal lymphangiomatosis in adults.

## Key findings

- The patient's condition was histopathologically confirmed as diffuse lymphangiomatosis, not pseudomyxoma peritonei.
- Complete cytoreduction achieved a successful outcome, emphasizing the importance of accurate preoperative diagnosis.
- Diffuse peritoneal lymphangiomatosis is extremely rare in adults and can mimic malignancy.

## Abstract

Localized cystic lymphangiomas (CL) are rare benign tumors deriving from the lymphatic system. CL is diagnosed more frequently in children than in the adult population and, although commonly affecting the cervical and axillary regions, can develop in various parts of the body. Abdominal cystic lymphangioma (ACL) comprises less than 5% of all CL cases.

A 35-year-old female patient with a history of benign appendectomy in childhood was transferred to our tertiary center for the operative management of a suspected extensive pseudomyxoma peritonei (PMP). In accordance with the multidisciplinary team discussion, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy was planned. Intraoperatively, a typical “jelly belly” with high disease burden throughout the abdominal cavity and the small pelvis was found. A multi-visceral resection with complete cytoreduction (CCR 0) was performed. The postoperative histopathological findings revealed a diffuse, partially cystic lymphangiomatosis involving the peritoneum extensively without evidence of PMP or malignancy.

ACLs are uncommon in the adult population, and diffuse peritoneal involvement is even rarer. Surgical management with complete resection is the preferred treatment option. Other benign cysts, as well as infectious diseases and malignancy, should be considered during the preoperative workup.