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 Table of Contents  
LETTER TO THE EDITOR
Year : 2021  |  Volume : 8  |  Issue : 4  |  Page : 170-173

Rare imaging-based diagnosis of pulmonary schistosomiasis: A case report


1 Department of Clinical Medicine, Dali University, Dali, China
2 Department of Respiratory Medicine, First Affiliated Hospital of Dali University, Dali, China
3 Department of Radiology, First Affiliated Hospital of Dali University, Dali, China
4 Department of Radiology, Yunnan Cancer Hospital, Kunming, China
5 Medical Imaging Center, The First Hospital of Kunming, Kunming, China

Date of Submission10-Aug-2021
Date of Acceptance07-Nov-2021
Date of Web Publication17-Aug-2022

Correspondence Address:
Bin Yang
Medical Imaging Center, The First Hospital of Kunming, Kunming 650224
China
Tengfei Ke
Department of Radiology, Yunnan Cancer Hospital, Kunming 650118
China
Wenshuai Duan
Department of Radiology, First Affiliated Hospital of Dali University, Dali 671000
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/RID.RID_14_21

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How to cite this article:
Chen X, Yang Q, He H, Zhang P, Duan W, Ke T, Yang B. Rare imaging-based diagnosis of pulmonary schistosomiasis: A case report. Radiol Infect Dis 2021;8:170-3

How to cite this URL:
Chen X, Yang Q, He H, Zhang P, Duan W, Ke T, Yang B. Rare imaging-based diagnosis of pulmonary schistosomiasis: A case report. Radiol Infect Dis [serial online] 2021 [cited 2022 Oct 6];8:170-3. Available from: http://www.ridiseases.org/text.asp?2021/8/4/170/353892



Dear Editor,

Schistosomiasis is an important infectious disease caused by some members of the genus Schistosoma, which are responsible for the infection of more than 200 million people in over 70 countries or regions worldwide, especially in Africa, South America, the Middle East and parts of Asia.[1] Schistosomiasis is mainly caused by three types of blood flukes in the Schistosoma genus: Schistosomahaematobium, found in Africa and the Middle East; Schistosomamansoni, found in Africa and South America; and Schistosomajaponicum, found in East Asia.[2] At present, the four countries with the highest prevalence of schistosomiasis in the world are China, Sudan, Brazil, and Egypt. The primary epidemic species in China is Schistosomajaponica, and the endemic area is mainly in the southern region of the Yangtze River Basin. The main clinical symptoms of pulmonary schistosomiasis are cough, wheezing, dyspnea, and chest pain.[3] Imaging examination is helpful for early diagnosis, treatment, analysis of the disease course, and evaluation of treatment effects. To improve our understanding of the disease, the imaging and clinical data for a patient diagnosed with pulmonary schistosomiasis at our hospital were analysed retrospectively.

The patient was a 62-year-old male farmer who lives in an epidemic area in Dali City, Yunnan Province, China. He was admitted to the hospital with a 1-week history of cough and a 1-day history of fever. There was no obvious cause for the onset of the cough, which was dry, paroxysmal, produced no phlegm and was more obvious at night. Physical examination revealed a body temperature of 37.8°C, rough breathing sounds in both lungs and minor wet rales in both lower lungs. Laboratory examination revealed a white blood cell count of 10.27 × 109, a neutrophil percentage of 75.5%, and no significantly abnormal tumor biomarkers. Gram-positive cocci (+) were detected in sputum smears, but no fungi or acid–fast bacilli were found. Chest computed tomography (CT) showed a round mass in the anterior segment of the upper lobe of the left lung. The mass was approximately 32.3 mm × 30.0 mm in size, the density was uneven, the CT value on plain scan was approximately 39 HU, the edges were not smooth, signs of spiculation could be seen, and local pleural thickening was apparent. An enhanced scan showed uneven enhancement, with a CT value of approximately 69 HU. A CT scan taken after 3 months of treatment showed significant absorption of the lesion compared with the pretreatment images [Figure 1] a-d]. Bronchoscopy and tissue biopsy were performed, and the pathological results showed deposition of calcified Schistosoma eggs in the alveolar cavity. Follow-up questioning revealed that the patient had a history of contact with infected water. On the basis of the imaging examination and pathological results, he was finally diagnosed as having pulmonary schistosomiasis [Figure e].
Figure 1: (a-c) Chest computed tomography shows a round mass (red arrows) in the anterior segment of the upper lobe of the left lung. The mass is approximately 32.3 mm × 30.0 mm in size, its internal density is uneven, the computed tomography value on plain scan is approximately 39 HU, the edges are not smooth, spiculation sign can be seen, and local pleural thickening is apparent. Enhanced scan shows nonuniform enhancement and a computed tomography value of approximately 69 HU. (d) After 3 months of treatment, chest computed tomography showed a flakey ground glass–density shadow (red arrow) in the anterior segment of the upper lobe of the left lung. The lesion had clearly been absorbed and reduced in size, and the density was significantly lower than previously. (e) Pathology analysis of the biopsy confirmed that the tissue was lung tissue, with calcified Schistosoma egg deposition (red arrows), thickened alveolar wall, telangiectasia, and hyperemia between the alveolar walls and a small amount of carbon deposition (H and E, 40 × 10)

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Schistosomiasis is a serious infectious disease. It is acquired by coming into contact with fresh water contaminated by Schistosoma cercariae. S.japonicum cercariae can enter the human body through the skin or the mucosa, after which they are carried to the portal vein through the circulatory and lymphatic systems and ultimately reach the pulmonary capillaries. Once they reach the lungs, the parasites develop into adults and lay eggs in the venous plexus. The eggs are transported upward and deposited throughout the venous system. Inflammation and immune response at the deposition site lead to the development of granuloma and fibrosis, leading to organ damage and corresponding clinical manifestations, including lung disease.[4],[5]

The clinical manifestations of pulmonary schistosomiasis are not typical and usually occur in acute and chronic phases. The clinical manifestations of acute pulmonary schistosomiasis usually appear 3–8 weeks after contact with infected water, and these can include shortness of breath, wheezing, dry cough, and chest pain.[6] Katayama syndrome can develop in patients with afirst-time infection, typically occurring weeks to months after primary infection. This syndrome is defined as systematic hypersensitivity to migrating adult Schistosoma parasites and eggs.[7] It is usually characterized by nocturnal fever, dry cough, wheezing, shortness of breath, myalgia, abdominal pain, and headache and is often accompanied by hepatosplenomegaly and an obvious increase in eosinophils.[8] The most common clinical manifestations of chronic pulmonary schistosomiasis are dyspnea and decreased exercise endurance. In severe cases, hypoxemia, chest pain and finger clubbing may occur, as well as cough and wheezing [2,9], possibly due to the development of pulmonary hypertension.[10] In addition, Schistosoma egg deposition in pulmonary vessels can lead to peripheral granuloma formation and fibrosis, as well as arteriolitis obliterans and pulmonary hypertension.[9] Laboratory examination often shows an obvious increase in eosinophils, accompanied by mild leukocytosis, and occasionally abnormal liver function and elevated IgE.[6]

Because the clinical manifestations of pulmonary schistosomiasis are relatively nonspecific, clinical misdiagnosis is common. The main clinical symptoms observed in the patient reported here were dry cough, fever, and a mild increase in the white blood cell population. The patient had no obvious Schistosoma-specific symptoms or signs, which is consistent with other reports in the literature.[6] The imaging findings associated with acute pulmonary schistosomiasis are mostly nonspecific and primarily include miliary nodules, similar to those seen in pulmonary tuberculosis, located in the lower lobe of the lung[11] that may also involve the pleura and pericardium.[12] Chronic schistosomiasis can exhibit characteristic nodular changes, mostly distributed in the middle and lower lobe of the lung, with or without ground-glass halo sign.[13] Chronic schistosomiasis can also appear similar to pulmonary hypertension on imaging.[14] The imaging feature of this patient was a round mass with uneven edges that could been misdiagnosed as peripheral lung cancer. Because this case have not signs of lung cancer, such _as lobulation, pleural indentation, vascular convergence and enlarged lymph nodes, as well as the normal tumour markers, it is easy to differentiate from lung cancer. It is important to be able to distinguish pulmonary schistosomiasis from peripheral lung cancer. At present, the gold standard for the diagnosis of pulmonary schistosomiasis is the detection of eggs in sputum, bronchoalveolar lavage fluid, or lung biopsy specimens.[5] In addition, eosinophilia and serum immunological examination are helpful for diagnosis. With recent advances in molecular biology technology, polymerase chain reaction techniques with high specificity and sensitivity have been applied to detect Schistosoma DNA, which makes it possible to diagnose schistosomiasis at various stages of clinical disease, diagnose Katayama syndrome, identify the active period of disease, and evaluate response to treatment.[15] In this case, the diagnosis was made after S.japonicum eggs which were found by lung biopsy.

The clinical and imaging manifestations of pulmonary schistosomiasis are nonspecific; thus the differential diagnosis includes peripheral lung cancer, tuberculoma, and inflammatory pseudotumour. Peripheral lung cancer is common in middle-aged and elderly individuals and manifests with symptoms such as cough, expectoration and hemoptysis. It is often accompanied by elevated tumor biomarkers. Furthermore, tumor grows rapidly, the shape is often irregular, the edges are rough, burr and lobulation signs can be seen, and there may be vacuole sign, pleural indentation sign, vascular convergence sign, and so on. Hilar and mediastinal lymph node enlargement and intrapulmonary and extrapulmonary metastatic tumors can be seen. Most patients with tuberculomas have a history of tuberculosis infection, and the tuberculomas tend to be located in the posterior segment of the upper lobe and the dorsal segment of the lower lobe. The nodules are generally <4 cm in diameter, exhibit a clear outline, smooth edges, high density, and calcification and are surrounded by satellite foci. Pleural shrinkage or thickening may occur, and enhanced scan often shows circular enhancement. Most patients with inflammatory pseudotumours have a history of pulmonary infection and large lesions that exhibit spiculation sign, peach tip sign, bronchial inflation sign, and so on. In addition, inflammatory pseudotumors exhibit uneven focus density, low CT density and rough edges, connection with the broad base of the pleura, more obvious enhancement, and slow growth. Some studies have reported that18 F-fluorodeoxyglucose positron emission tomography/CT (18 F-FDG PET/CT) is helpful in the diagnosis of schistosomiasis. The18 F-FDG PET/CT imaging not only makes early detection of tumours possible but also allows the detection of infections.[16] However, this technique lacks specificity. Imaging examination is helpful for early diagnosis, treatment evaluation, disease course monitoring, and evaluation of cure of pulmonary schistosomiasis, and a diagnosis of schistosomiasis should be considered in combination with clinical manifestations, imaging examination, laboratory examination, and epidemiological data. The diagnosis should ultimately be confirmed by pathological examination.

In summary, the clinical and imaging features of pulmonary schistosomiasis lack specificity, and the disease is relatively rare, which can easily lead to misdiagnosis. Imaging examination is helpful for early diagnosis and evaluation of treatment effectiveness, disease course, and curative effect for pulmonary schistosomiasis, but the final diagnosis still depends on pathological examination.

Acknowledgment

We thank Emily Crow, Ph.D., from Liwen Bianji (Edanz) (www.liwenbianji.cn), for editing the English text of a draft of this manuscript.

Financial support and sponsorship

This work was supported by the program for Cultivating Reserve Talents in Medical Disciplines from the Health Committee of Yunnan Province(H-2018008 for B.Y). And the National Natural Science Foundation of China (NSFC) (82160348 for Y.B).

Conflicts of interest

There are no conflicts of interest.



 
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