A primary pleural hydatid cyst was discovered months after an undiagnosed pneumothorax: A diagnostic and therapeutic dilemma in a rare case report from Syria

Abstract

Introduction

Primary pleural hydatid cysts (PPHCs) are a rare clinical condition caused by the larval stage of the parasite Echinococcus granulosus. They occur in <1 % of all hydatid cysts in the body and can cause serious complications such as pneumothorax, pleural effusion, and mediastinal shift.

Presentation of case

We report a rare case of a 28-year-old female who was initially misdiagnosed and ignored her pneumothorax for several months, resulting in progressive dyspnea and chest pain. After performing radiological images, a primary pleural hydatid cyst was suspected. She was surgically treated and the cyst was removed by our doctors and the patient improved without any significant complications.

Discussion

PPHCs are a challenging diagnosis due to their nonspecific symptoms and low prevalence. They can mimic other pleural diseases such as tuberculosis, empyema, or malignancy. The diagnosis of PPHCs requires a high index of suspicion and a combination of imaging, serology, and histopathology. The treatment of choice is surgical removal of the cyst, along with perioperative anthelmintic therapy to prevent recurrence and anaphylaxis.

Conclusion

PPHCs are a rare but potentially life-threatening condition that requires early diagnosis and management. Clinicians should be aware of this entity and include it in the differential diagnosis of pleural diseases, especially in developing countries. Surgical treatment is effective and safe, and can improve the quality of life of patients with PPHCs.

Highlights

• •Extrapulmonary intrathoracic cysts are rare clinical entities.
• •It is important to include hydatid cysts in the differential diagnosis when a patient has simple pneumothorax.
• •Pleural cysts may cause trapped lung and pleural fibrosis.

Abbreviations

PPHCs	primary pleural hydatid cysts
CXR	chest X-ray
MVP	mitral valve prolapse
BP	blood pressure
SpO2	oxygen saturation
CT	computed tomography
VATS	video-assisted thoracoscopic surgery
ICU	intensive care unit
ELISA	enzyme-linked immunosorbent assay

1. Introduction

Hydatid disease is a condition caused by the parasite Echinococcus granulosus, which forms cystic lesions in various organs [1]. The parasite is transmitted to humans through the ingestion of food contaminated with dog feces that contain its eggs, as dogs are the definitive host of this parasite [2]. The cysts grow slowly and may not produce any symptoms for years after infection [1]. The most common organs affected by the cysts are the liver and lungs, but they can also occur in other sites such as the bones or the pericardium. However, the pleural cavity is a very rare location for primary hydatid cysts [3]. In this report, we present a rare case of a 28-year-old female who was diagnosed with a large primary hydatid cyst in the intrapleural cavity after being admitted with severe dyspnea. We also review her medical history and previous X-rays, which revealed that she had an undiagnosed pneumothorax for months. This case is described in accordance with the criteria of SCARE [4].

2. Presentation of case

A 28-year-old female, who was a non-smoker, came to the hospital with dyspnea and pain in the right side of her chest. She did not have fever, chills, or any other symptoms. She had been experiencing these symptoms for four months, and they had become more severe over time. She said that she had seen a doctor at a medical clinic before, who had ordered a chest X-ray (CXR) and some laboratory tests. The doctor had told her that everything was normal and had given her only analgesics. She also said that she had been diagnosed with mitral valve prolapse (MVP) two years ago.

3. On clinical examination

The patient presented with tachypnea, with a respiratory rate of 30 breaths per minute, a blood pressure (BP) was 110/80 mmHg, her temperature was 36.8 °C, and her oxygen saturation (SpO2) was 93 % on room air. The pulmonary examination on the right side showed reduced breath sounds, no vocal fremitus, and dullness to percussion. The clinical examination of the abdomen and heart was normal. In addition, the spleen and liver echo did not show any hydatid cysts and the laboratory tests were within the normal limits in Table 1.

Table 1.

Laboratory tests.

Test name	Value	Normal range	Unit
WBCS	8	4.5–11	×109/L
Neutrophils	61	40–75	%
PT	90	70–120	%
HB	12	12–16	g/dL
HT	36	36–48	%
PLT	343	150–450	×109/L
ALT	11	<35	U/L
AST	13	<35	U/L
Creatinine	0.6	0.6–1.2	mg/dL
Urea	16	10–20	mg/dL
Na	144	135–145	mEq/L
K	4.5	3.5–5	mEq/L

4. The chest radiograph

The previous CXR revealed an unnoticed right pneumothorax that caused the right lung to collapse completely, as seen in Fig. 1.

Fig. 1.

The patient's old chest X-Ray showing complete right pnemothorax with right lung collapse.

The CXR on admission showed a total opacification of the right hemithorax with mediastinal shift to the left, as shown in Fig. 2.

Fig. 2.

The admission Chest X-ray revealing complete opacification of hemithorax on the right side with mediastinal shift to the left.

The computed tomography (CT) scan demonstrated a big cystic mass in the right lung, along with lung collapse and fluid accumulation in the pleural space, as seen in Fig. 3. Based on the patient's rural residence, where hydatid cysts are common, and the correlation of the patient's age, clinical symptoms, and radiological images that revealed a round, well-defined fluid-filled shadow, we strongly suspected hydatid cysts. To avoid puncturing the hydatid cyst and releasing its contents into the pleural cavity, which could increase the risk of cyst recurrence and anaphylactic shock, we did not perform a thoracentesis or a tissue biopsy before surgery. Instead, we opted for VATS (video-assisted thoracoscopic surgery), a minimally invasive surgical technique to diagnose and treat chest diseases.

Fig. 3.

The chest CT showing a right lung cystic lesion.

5. The surgical procedure

The surgical team performed a video-assisted thoracoscopic surgery, which revealed a large hydatid cyst in the pleural cavity, along with pleural effusion and a collapsed right lung. The pleura was also irregularly thickened and fibrotic. The team drained the serous pleural effusion and then proceeded to a right posterolateral thoracotomy through the fifth intercostal space. They removed the pleural fibrosis completely in Fig. 4 and evacuated the large intact hydatid cyst in Fig. 5 and Video 1. After that, the lung was found to be trapped, as seen in Fig. 6, so performed a complete lung decortication to release the trapped lung, as shown in Fig. 7.

Fig. 4.

The dissected pleural fibrosis and thickening.

Fig. 5.

A large non-ruptured hydatid cyst was seen in the thoracotomy.

Fig. 6.

A trapped lung was seen during the thoracotomy.

Fig. 7.

The lung after complete lung decortication during the thoracotomy.

The team ensured adequate lung ventilation and re-expanded the right lung without causing any rupture or damage. They closed the wound in layers and completed the procedure without any major complications. The patient was extubated after the surgery and did not need admission to the intensive care unit (ICU).

6. Postoperatively

The patient was admitted to the medical floor for two days after the surgery and received antibiotics, analgesics, and Albendazole 400 mg twice a day. Her symptoms improved 24 h later and the chest X-ray showed that the lung had re-expanded, as shown in Fig. 8. The chest tube drained 300 ml/h in the first 24 h. On the second day, the drainage decreased to 100 ml/h and the patient's general condition was good. The tube was removed and the patient was discharged with a prescription of oral Albendazole 400 mg twice a day for six months. However, the patient did not return for follow-up and we lost contact with her despite numerous attempts to communicate. This was unfortunate because hydatid cysts need long-term follow-up to assess recurrence.

Fig. 8.

A chest X-ray 24 h after the thoracotomy revealing the re-expanded lung.

7. Discussion

Hydatid cysts are fluid-filled sacs caused by the tapeworm Echinococcus granulosus. Humans can get infected by eating food contaminated with the eggs of this parasite. The larvae of the parasite enter the abdomen through the digestive tract and then spread to different organs via the lymphatic system or the portal vein. The most common sites for hydatid cysts are the liver and the lungs, but they can also develop in other organs such as breast,kidneys, heart, thyroid, muscles, spleen, brain, and the bone marrow [5,6]. Hydatid cysts in the liver are more frequent than those in the lungs, and the right lung is more affected than the left. However, the lung tissue is more elastic than the liver tissue, so the cysts grow faster in the lungs than in other organs [7]. They also grow faster in young people than in adults, and their sizes can vary from a few millimeters to several centimeters, reaching up to 5 cm within a year of their formation [8]. Hydatid cysts are classified as intrathoracic extrapulmonary when they are located in the following structures: chest wall, mediastinum, pleura, diaphragm, heart, or pericardium [9]. These are rare sites, accounting for 7.4 % of all cases, as in our report, where we detected a large hydatid cyst in the pleural cavity without any other chest lesion, confirming our diagnosis of primary pleural hydatid cyst [10]. In general, hydatid disease in the pleural cavity is secondary to lung involvement in most cases. Primary pleural hydatid disease is uncommon, with a rate of <1 %, and the number of documented cases in the medical literature is very limited compared to the rest of the cases [11]. The main reason for the growth of cysts in the pleural area is the lack of blood vessels between the layers of the pleura, which allows some electrolytes such as calcium, chloride, potassium, and other important nutrients for the growth and development of cysts to diffuse through the hydatid cyst membrane [12]. Hydatid cysts are asymptomatic in 15 % of cases and are discovered incidentally when performing a simple radiograph, or they present with various symptoms such as: chest pain, dyspnea, chronic cough, or decreased lung volume [13]. Coursay et al. reported in a study of a sample of 14 patients that chest pain and dyspnea were the most common manifestations [10]. Machboua et al. reported on a sample of 8 patients of both genders about the presence of three constant symptoms in all patients, which were: cough, dyspnea, and chest pain [14]. In our case, the patient only had dyspnea and chest pain without any other symptoms such as fever or night sweats. Anaphylactic shock or tension pneumothorax may occur in patients when the cyst ruptures, and other complications of cysts include simple pneumothorax and empyema [13]. In a previous study, Erkoç et al. reported on a rare cause of parasitic pleural effusion, which was the presence of a hydatid cyst in an unusual site such as the pleura and its rupture [11]. In our case, both simple pneumothorax, mediastinal shift, and right pleural effusion had already occurred, but the cyst was intact. Furthermore, a simple pneumothorax, which had been neglected for several months, was the most important finding and It indicated the possibility of a hydatid cyst as an underlying cause. The term trapped lung refers to the inability of the lung to expand in the chest cavity, resulting in its collapse or complete atelectasis due to the presence of an obstacle in the pleura or an obstruction within the bronchus [15]. The most common cause of trapped lung in the past was a therapeutic pneumothorax for treating tuberculosis. Some of the current common causes are autoimmune pleurisy, complex parapneumonic effusion, chest trauma, thoracic radiation, and uremia [16]. Another condition associated with non-expandable lungs is pleural fibrosis, which occurs as a natural response to the presence of inflammation, malignancy, or other diseases such as tuberculosis [17]. Although the pathogenic mechanism of pleural fibrosis in our patient is not fully understood, it caused a trapped and atelectatic lung as a natural consequence of the presence of the peel that caused its collapse, prompting the surgeon to perform surgical decortication of the lung. A case similar to ours was reported by Bara et al. where the patient developed pleural thickening due to the hydatid cyst, which resulted in a trapped lung [3]. CT, X-ray, and ultrasound are all diagnostic methods that are useful for planning surgery for cysts. Immunodiagnostic tests can also be used, where the sensitivity of the enzyme-linked immunosorbent assay (ELISA) test reaches up to 95 % or more [18]. Although mortality may reach 4 % during surgery, surgery is the best option for removing hydatid cysts when there is no contraindication to surgical intervention [19]. After that, the patient's treatment is followed by administering Albendazole 400 mg orally for at least 6 months [20].

8. Conclusion

In conclusion, our case demonstrates the major complications that can arise from primary hydatid cysts in the pleural space, especially pneumothorax. The triad of pleural hydatid cyst, pleural fibrosis, and trapped lung is an uncommon condition that has been rarely reported in the medical literature. We highlight the need for further research on the pathogenesis of pleural fibrosis caused by hydatid cysts.

The following is the supplementary data related to this article.

Video 1

Removing pleural fibroids and then starting to remove the unruptured hydatid cyst.

Informed consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

(Ethical Committee N° NAC 302) was provided by the Ethical Committee NAC of University of Kalamoon, Syria on 19 October 2023.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

HH, TA, MJ, JA, KA, have participated in writing the manuscript, and reviewing the literature. Hamdah Hanifa critically and linguistically revised the manuscript. SAA conceived and supervised the conduct of the study.

All authors read and approved the final manuscript.

Guarantor

Hamdah Hanifa, Al-Dandashi National Group, Yaafour, Damascus, Syria.

Research registration number

Not applicable.

Declaration of competing interest

The authors declare that they have no competing interests.

Data availability

All data generated or analysed during this study are included in this published article.