Lung India

: 2019  |  Volume : 36  |  Issue : 3  |  Page : 273--274

Lung hydatid cyst, an immunological process, not a pearl formation

Beuy Joob1, Viroj Wiwanitkit2,  
1 Sanittion 1 Medical Academic Center, Bangkok, Thailand
2 Department of Biological Science, Joseph Ayobabalola University, Ikeji-Arakeji, Nigeria

Correspondence Address:
Dr. Beuy Joob
Sanittion 1 Medical Academic Center, Bangkok

How to cite this article:
Joob B, Wiwanitkit V. Lung hydatid cyst, an immunological process, not a pearl formation.Lung India 2019;36:273-274

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Joob B, Wiwanitkit V. Lung hydatid cyst, an immunological process, not a pearl formation. Lung India [serial online] 2019 [cited 2019 Dec 12 ];36:273-274
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We read with great interest the publication entitled, “'Pearl' in the lung: Hydatid membrane” by Baldi et al.[1] Baldi et al. reported the case of a patient with lung hydatid cyst presenting with “a glistening pearly white membranous structure occluding the lumen of the right upper lobe anterior segment.”[1] Baldi et al. mentioned for an interesting finding from bronchoscopy examination and proposed that “the mechanism of formation of hydatid cyst (hosts reaction to a parasite) is quite analogs to the formation of natural pearls, hence the title.”[1] We agree that this is an interesting uncommon case of hydatid disease, a helminthic infestation. Nevertheless, the statement regarding the nature and development of white membranous structure is not correct. Regarding the hydatid cyst formation, the inflammation is the primary biological change, and the role of leukocyte in inflammatory response is detectable.[2] Fibrosis is the common pathology of hydatid cyst in internal organ.[3] This pathological process is totally different from that of pearl formation. For pearl formation, the basic process is the mineralization controlled by shell matrix gene.[4] There is no immunological process or inflammatory response in pearl formation, but those phenomena are observable in hydatid cyst formation. Hence, there should be no analog to the formation of natural pearls in this patient. In the present case, the appearance of the white membranous structure might look like a pearl, but this picture should be due to the light effect which is a common phenomenon during performing flexible bronchoscopy examination. The light reflection might result in the whitish pearl-like appearance seen in the clinical picture in the report by Baldi et al.[1]

Clinically, hydatid disease is an important uncommon parasite infection. The disease is sporadically reported from several countries, especially those in the tropical zone. The patient might present with nonspecific respiratory complaint. The chronic history is common. Due to the nature of silent parasitic infection, some cases might not have any clinical symptom. The diagnosis of lung hydatid cyst is usually by chance. Indeed, the diagnosis of lung hydatid cyst is usually difficult. The lung imaging usually shows a less mass. In the present case report, chest X-ray abnormality is also observed.[1] The unexplained lung mass is a common first clinical presentation of lung hydatid cyst. The diagnosis of lung hydatid cyst is usually delayed. In general, the final diagnosis by fine-needle biopsy is usually not possible.[5] At present, the recommended gold standard for diagnosis of lung hydatid cyst is combined video bronchoscopy and bronchoalveolar lavage fluid examination.[5] Of interest, the clinical data in the present case report are extremely limited. In the present case report, the detail of final diagnosis is also not available. In additional, there is no histopathological figure. Nevertheless, the white membranous structure was not finally clarified for its nature. The treatment and outcome is also not mentioned.

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1Baldi M, Dhooria S, Agarwal R, Sehgal IS. “Pearl” in the lung: Hydatid membrane. Lung India 2019;36:176.
2Treves S, Ali-Khan Z. Characterization of the inflammatory cells in progressing tumor-like alveolar hydatid cyst 2. Cell surface receptors, endocytosed immune complexes and lysosomal enzyme content. Tropenmed Parasitol 1984;35:231-6.
3Wu XW, Peng XY, Zhang SJ, Niu JH, Sun H, Xi Y. Formation mechanisms of the fibrous capsule around hepatic and splenic hydatid cyst. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2004;22:1-4.
4Sato Y, Inoue N, Ishikawa T, Ishibashi R, Obata M, Aoki H, et al. Pearl microstructure and expression of shell matrix protein genes MSI31 and MSI60 in the pearl sac epithelium of Pinctada fucata by in situ hybridization. PLoS One 2013;8:e52372.
5Basu A, Dhamija A, Agarwal A, Jindal P. Ruptured pulmonary hydatid disease mimicking a lung mass: Diagnosed by flexible video bronchoscopy. BMJ Case Rep 2012;2012. pii: bcr2012006977.