Lung abscess in a migrant

Sir,

Echinococcosis, or hydatidosis, is a parasitic disease caused by infestation by larvae of several species of a cestode parasite or gastrointestinal worm (tapeworm, genus Echinococcus) of importance to livestock production and public health [1].

Hydatid cysts can develop in virtually every organ, most commonly in the liver and lungs [2]. The most common complication is cyst rupture and infection.

The purpose of this case report is to highlight some important features of this type of Echinococcus granulosus infection.

In April 2022, a 20-year-old male presented to the emergency department with chest pain. The patient had been complaining for two months of a pressing central chest pain, always at rest, usually when lying down, with no gastroesophageal reflux, nausea, dyspnoea or palpitations. The pain radiated into both arms, causing weakness, and disappeared within 20 minutes. The patient came from a rural area of Morocco, was a pack-a-day smoker, and his father owned a farm. Blood analysis showed no leukocytosis, neutrophilia, or eosinophilia, and no elevated liver enzymes. An anteroposterior chest radiograph and an abdominal thoracic CT scan with contrast (Figure 1) revealed a 9.5 × 8.2 cm thin-walled cystic lesion in the axial plane and an 11.5 cm long craniocaudal thin-walled cystic lesion in the right hemithorax.

Figure 1.

Thoraco-abdominal CT with contrast

The liver, pancreas, spleen, adrenal glands, and both kidneys were unremarkable. Surgery to remove the cyst was recommended, but the patient refused. He subsequently returned for surgery in May 2024, at which time an immunoglobulin G serology test for hydatidosis was performed using a commercially available indirect haemagglutination assay (IHA) (Echinococcosis Fumouze; Laboratoires Fumouze, Levallois-Perret, France), with a negative result. An apparent hydatid cyst was removed and confirmed in the microbiology laboratory (Figure 2).

Figure 2.

Scolexus: spherical, about 0.3 mm in diameter. With four oval suckers and a rostellum armed with two rows of hooks, with a total of 30-60 hooks

Treatment with albendazole (400 mg) was started, completing 28 days after surgery with good clinical evolution, remaining asymptomatic months after surgery with normal thoracic radiography.

Medical history remains a fundamental tool for suspecting rare diseases in our environment. This parasite is endemic in Morocco, as well as in other countries in Central and South America, Central and Southern Europe, some sub-Saharan countries, Russia, and China.

Of patients with cystic echinococcosis, 85–90% show single organ involvement, and more than 70% harbor a solitary cyst. The liver is the most common site of cyst formation, followed by the lungs in 10–30% of cases and other organs in 10% of cases. In children and young adults, the lungs may be the most common site of cyst formation and are giant because of their greater lung elasticity. Pulmonary hydatid cysts are mainly located in the lower lobes (55-70% of cases) and can sometimes be multiple (30%) and bilateral (20%). Among patients with pulmonary cysts, 20-40% also have liver cysts [3]. Most patients with pulmonary hydatid disease do not show liver involvement, which suggests that either the liver filter has not worked properly or has been bypassed, but it does not exclude the possibility of a simultaneous intrahepatic transplantation. The lungs also facilitate cyst growth due to the negative pressure and compressibility of the lungs, which may explain the high prevalence of the disease in the lungs and the easy growth of cysts in children.

The negative serology for fully established hydatidosis is also striking in this case. Immunodiagnostic tests for serum antibodies or circulating antigens provide evidence to confirm pulmonary echinococcosis. The commercial indirect haemagglutination test used has a sensitivity of 88% and a specificity of 98.4% at the manufacturer’s recommended cut-off of 320. However, an enzyme-linked immunosorbent assay or indirect haemagglutination test is found positive in only around half of patients with pulmonary cysts and over 90% of patients with liver cysts [4].

Hydatid fluid is the main source of antigens used both for primary immunodiagnosis and for monitoring patients after surgical or pharmacological treatment. However, problems have been encountered in standardizing its use, as well as in terms of its sensitivity and specificity [5,6]. For example, a high percentage of patients with clinically or surgically confirmed hydatidosis are seronegative, while cross-reactivity issues are common with sera from individuals infected with other helminths, mainly E. multilocularis and Taenia solium [7]. The use of molecular biology techniques has also led to the availability of a considerable range of recombinant proteins and synthetic peptides, the use of which, individually or in combination, has greatly improved the diagnostic performance of available techniques [8]. However, despite all these advances, there is currently no standardised technique that combines high diagnostic sensitivity and specificity [9].

Although surgery is effective in treating pulmonary hydatidosis in patients with both complicated and uncomplicated cysts, it is essential that surgery be performed before the cysts rupture [10].

Funding

None to declare.

Conflicts of interest

The authors declare that they have no conflicts of interest.