A huge pseudomyxoma pleurii mimicking hydatid cyst: A case report.

Introduction: Pseudomyxoma pleurii is a rare disease that is defined by the pleural extension of pseudomyxoma peritonei, usually secondary to a mucinous neoplasm of the appendix or ovary. It is characterized by diffuse mucinous deposits on the pleural surface.

Case Presentation: A 31-year-old woman presented to the hospital with dyspnea, an increased respiratory rate, and decreased oxygen saturation. Following an appendectomy for a perforated mucinous appendiceal tumor eight years ago, the patient underwent multiple surgeries for the resection of mass deposits in the peritoneal cavity. At presentation, her chest computed tomography with contrast revealed cystic mass deposits on the right-side pleura with a massive multi-locular pleural effusion mimicking hydatid cyst. Upon histopathologic examination, multiple small cystic structures lined by tall columnar epithelium with basally placed bland nuclei floating in the mucin pools were noted.

Clinical Discussion: Pseudomyxoma peritonei often leads to abdominal distention, intestinal blockage, anorexia, cachexia, and eventually death. It rarely spreads outside the abdomen, and its extension to the pleura is extremely unusual, with only a small number of cases documented in the literature to date. Radiologically, pseudomyxoma pleurii may resemble hydatid cyst of the lung and pleura.

Conclusion: Pseudomyxoma pleurii is a rare entity with a poor prognosis that usually arises secondary to Pseudomyxoma peritonei. The risk of morbidity and mortality is reduced by early diagnosis and treatment. The present case places emphasis on the inclusion of pseudomyxoma pleurii in the differential diagnosis of pleural lesions in patients with the history of appendiceal or ovarian mucinous tumors.