Unusual Primary Pleural Localizations of Hydatid Cysts: A Systematic Review

Introduction: Primary pleural hydatidosis is a rare manifestation of cystic echinococcosis, a zoonotic parasitic disease caused by Echinococcus granulosus. While the liver and lungs are the most common sites of infection, pleural involvement is uncommon and often overlooked. This review aims to provide a comprehensive overview of primary pleural hydatid cysts by analyzing their epidemiological patterns, clinical presentations, diagnostic approaches, treatment strategies, and patient outcomes. Materials: A systematic literature search was conducted using PubMed, Scopus, Web of Science, and Google Scholar, without time restrictions, employing MeSH terms related to pleural and extrapulmonary hydatidosis. Forty-four articles published between 1964 and 2024 were included, yielding data on 36 patients. Results: A total of 36 cases of primary pleural hydatid cysts were identified from 34 published reports. Patients’ ages ranged from 10 to 79 years (median, 24 years), with a male predominance (58.3%). The most frequently reported symptoms were chest pain (58%), dyspnea (50%), cough (47%), and fever (31%), while thoracic masses and asymptomatic presentations were less common (11% each). Right-sided pleural involvement was observed in 64% of cases. Hydatid serology was positive in 13 patients, negative in 5, and unreported in 18. Pleural fluid analysis was performed in 4 cases, all of which were positive for Echinococcus granulosus or hydatid-specific IgG. Imaging primarily included chest X-ray (83%), computed tomography (92%), and ultrasound (14%). Treatment strategies included surgery alone (47%), surgery with postoperative albendazole (39%), combined pre- and postoperative albendazole with surgery (11%), and albendazole monotherapy (3%). The most favorable outcomes were observed with combined pre- and post-operative albendazole and surgery (100%), followed by surgery with post-operative albendazole (71%). Discussion: Primary pleural hydatid cysts are exceptionally rare, with only a few cases reported worldwide. Their pathogenesis remains unclear, although hematogenous dissemination may explain isolated pleural involvement without hepatic or pulmonary disease. Clinical manifestations are often nonspecific, and diagnosis relies primarily on imaging, particularly computed tomography, which aids both detection and surgical planning. Serological tests may support diagnosis but have limited specificity. Surgery remains the treatment of choice, while adjuvant albendazole therapy helps reduce the risk of recurrence. Conclusion: Given the rarity and non-specific presentation of primary pleural hydatid disease, a high index of clinical suspicion is necessary. Early diagnosis and combined surgical and medical treatment generally result in good prognoses. Further studies are warranted to refine diagnostic and therapeutic protocols.