|LETTER TO THE EDITOR
|Year : 2014 | Volume
| Issue : 1 | Page : 70-71
Isolated renal hydatid cyst
Akshatha S Kamath1, Srinivas P Rao2, AS Ramaswamy1, Vaibhav J Nayak2
1 Department of Pathology, Peoples Education Society Institute of Medical Sciences and Research-Kuppam, Chittor, Andhra Pradesh, India
2 Department of Urology, Peoples Education Society Institute of Medical Sciences and Research-Kuppam, Chittor, Andhra Pradesh, India
|Date of Web Publication||10-Mar-2014|
Akshatha S Kamath
G6, Sai Jaya Durga Apartments, Lakshmipuram 1st Main, Mysore, Karnataka - 570 004
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kamath AS, Rao SP, Ramaswamy A S, Nayak VJ. Isolated renal hydatid cyst. J NTR Univ Health Sci 2014;3:70-1
Renal echinococcosis, also called the hydatid cyst of the kidney, is a rare acquired disease caused by the parasite Echinococcus. Kidney is the third commonest organ involved, after liver and lungs.  Usually, the kidneys are involved as a part of multiple organ hydatidosis. However, isolated involvement of the kidney is extremely rare, comprising about 2-3% of all the cases of hydatid disease.  We are reporting a case of isolated renal hydatid cyst.
A 65-year-old female presented with the complaint of pain and fullness in the right flank region, which he had been having for the past 1 year. There was no history of associated urinary complaints. On physical examination, a lump was palpated in the right lumbar region, which was tender with a smooth surface and ill-defined margins. The kidney function tests were normal. All hematological and biochemical investigations were within normal limits. Urine microscopy showed no abnormalities.
Computed tomography of abdomen showed a large cystic lesion arising from the upper pole of the right kidney, measuring 11.8 × 9.1 × 9.5 cm with multiple internal septations. Focal areas of peripheral calcifications were noted within the mass. The mass lesion demonstrated no definitive evidence of invasion. There were no similar lesions in the other abdominal viscera [Figure 1].
|Figure 1: Computed tomography scanning image showing the right kidney displaying a unilocular cyst with multiple internal septations|
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A presumptive diagnosis of renal hydatid disease was done based on the radiological findings, and nephrectomy was planned as a modality of treatment. The postoperative period was uneventful.
The right nephrectomy specimen received in histopathology measured 16 × 13 × 9 cm. On cut section, upper pole and middle part of the kidney was replaced by a unilocular cyst measuring 12 cm in the greatest dimensions, containing multiple daughter cysts [Figure 2]. Microscopic examination showed laminated membranes, brood capsules, and scolices bearing lanceolate hooklets of a hydatid cyst. The adjacent renal parenchyma was compressed and showed focal areas of calcification and features of chronic pyelonephritis [Figure 3].
|Figure 2: Cut-opened specimen of the right kidney showing a unilocular hydatid cyst with multiple daughter cysts|
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|Figure 3: Laminated membranes of hydatid cyst with adjacent renal tissue showing compression and features of chronic pyelonephritis (H and E, 100×). (Inset) Brood capsules showing scolices and lanceolate hooklets (H and E, 450×)|
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Human hydatid disease is only a tangential accident in the natural cycle of the hydatid worm, Echinococcus granulosus. The dog is the usual definitive host which may feed on the carcass or offal of the intermediate host, which is usually sheep or cattle harboring hydatid cysts, when they die or are slaughtered. Humans are accidental hosts who constitute a blind alley in the cycle of transmission. 
The pathogenesis of primary renal hydatid disease of the kidney is postulated by the passage of hydatid embryo through the portal system into the liver and retroperitoneal lymphatics. The hydatid cyst of the kidney, with all the three layers, i.e., pericyst, ectocyst, and endocyst, is considered to be closed.
Common urology presentation of renal hydatidosis is of chronic dull flank pain or low back discomfort from cystic pressure; it rarely presents with hydatiduria, ureteropelvic obstruction, and chronic renal failure. ,
Imaging findings in hydatid disease depend on the stage of cyst growth [i.e., whether the cyst is unilocular, contains daughter cysts, or is partially or completely calciﬁed (dead)]. A difference in attenuation and signal intensity between the ﬂuid in the central portion of the cyst and that in the peripheral cysts is a typical finding in echinococcosis due to a difference in content. Renal hydatid disease may mimic other diseases such as multicystic renal cell carcinoma. Detection of a cystic lesion with internal septations and sand and wall calciﬁcations in the proper clinical setting allows the correct diagnosis in a majority of cases.
Lesions with a solid appearance may be encountered. Lack of internal contrast enhancement allows one to classify them as hyperattenuating or hyperintense cystic lesions and to avoid misinterpreting them as tumors. Intact cysts may produce a low level of antigenic stimulation. Advanced radiologic techniques such as computed tomography (CT) and magnetic resonance (MR) imaging remain the mainstay of diagnosis. 
Surgical options for renal hydatid cyst include total excision, wedge resection or partial nephrectomy, partial pericystectomy followed by capitonnage, re-approximation of the pericyst, or marsupialization. Renal sparing surgery by way of partial excision is possible in 75% cases and is the most adopted treatment whenever possible. ,,
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|2.||Mudholkar VG, Suwamkar SV, Deshpande SA, Kadam PN. Isolated renal hydatid disease with gross hydatiduria. Indian J Pathol Microbiol 2011;54:640-1. |
|3.||CK Jayaram Paniker. Textbook of medical parasitology. 6 th ed. New Delhi: Jaypee; 2007. p. 150-5. |
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[Figure 1], [Figure 2], [Figure 3]