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Year : 2018  |  Volume : 61  |  Issue : 3  |  Page : 410-413
Collecting duct carcinoma kidney masquerading as hydatid cyst: A rare case report and review of literature

Department of Pathology, M. L. N. Medical College, Allahabad, Uttar Pradesh, India

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Date of Web Publication13-Jul-2018


Cystic renal masses pose diagnostic challenge especially when they belong to Bosniak Type II and III. Septal and nodular enhancement on computed tomography (CT) is the strongest predictor of malignant process. A unilocular cyst with a calcified rim or a multilocular cystic lesion with heterogeneity on CT goes in favor of hydatid disease. We report a case in a 65-year-old female who presented with painless hematuria, was found to have a cystic mass in the right kidney. The mass turned out to be collecting duct carcinoma after histopathological examination though imaging studies were in favor of a hydatid cyst.

Keywords: Bosniak, collecting duct, renal cyst

How to cite this article:
Kumar V, Misra V, Chaurasiya D, Verma N. Collecting duct carcinoma kidney masquerading as hydatid cyst: A rare case report and review of literature. Indian J Pathol Microbiol 2018;61:410-3

How to cite this URL:
Kumar V, Misra V, Chaurasiya D, Verma N. Collecting duct carcinoma kidney masquerading as hydatid cyst: A rare case report and review of literature. Indian J Pathol Microbiol [serial online] 2018 [cited 2021 Sep 23];61:410-3. Available from: https://www.ijpmonline.org/text.asp?2018/61/3/410/236632

   Introduction Top

Collecting duct carcinoma (CDC) accounts for <1% of all the renal carcinomas. Reports suggest that this tumor arises from the collecting duct epithelium in contrast to majority of the renal cell carcinoma which arises from the proximal tubular epithelium.[1] Evidence of its origin from the collecting duct is supported by its location in the renal medulla, architectural similarity to the distal collecting duct tubules, atypical hyperplasia of the collecting duct epithelium adjacent to the neoplasm and immunohistochemical markers.[2],[3],[4] It was first reported by Foot and Papanicolaou in 1949.[5] CDC is characterized by distinct clinicopathological features, aggressiveness, and poor prognosis which distinguishes it from rest of the Renal Cell Carcinoma.[6] In view of lesser number of cases and aggressive clinical behavior, we present a case of CDC along with brief review of literature.

   Case Report Top

A 65-year-old female presented with painless hematuria for 2 months. Contrast-enhanced computed tomography (CT) revealed a cystic area in the right kidney measuring about 3 cm in size with uniform wall thickening. No solid elements were identified. Foci of calcifications were seen in the middle part of the cyst. Both poles were normal [Figure 1]a. Based on the imaging findings, a clinicoradiological diagnosis of renal cyst with uniform wall thickening favoring renal hydatid cyst was made. The old age of the patient, persistent hematuria along with the presence of minimally complicated cyst with thickened wall on radiology which was centered in the medulla of the kidney prompted the surgeon to perform a radical nephrectomy. Specimen was sent for histopathological examination. Gross examination revealed a mass measuring 3.5 cm in diameter arising from the anterolateral surface of the kidney. Cut surface showed a mass centered in the medulla, was partially cystic, partially firm in consistency. Peripheral area was firm and white, whereas center of the mass was soft, showing small papillary fronds with areas of necrosis [Figure 1]b and [Figure 1]c. Sections processed showed an irregular tumor mass with infiltrative margins disposed in angulated tubules and tubulopapillary pattern [Figure 2]a, [Figure 2]b, [Figure 2]c. In places, diffuse arrangement of tumor cells was noted. Tumor cells were round to oval with hyperchromatic nuclei and prominent nucleoli (Fuhrman grade 3/4) [Figure 3]a. Hobnail pattern of tumor cells was also noted [Figure 3]b. Infiltrative margins showed marked desmoplasia with areas of hyalinization and calcification [Figure 2]c. Cortex was infiltrated by the tumor cells with extension in between surrounding normal tubules and glomeruli [Figure 2]a and [Figure 2]b. Interstitium was infiltrated by mixed inflammatory infiltrate comprising of lymphocytes and neutrophils.[Figure 2]d Dysplastic changes in the tubular lining were noted at the junction of tumor and cortex [Figure 3]c. Normal appearing transitional epithelium at the pelviureteric junction ruled out the possibility of gland forming urothelial carcinoma. [Figure 3]d Lymph node sent separately showed no tumor deposits with infiltration by tumor in the surrounding fibrofatty tissue [Figure 4]a.
Figure 1: (a) Computed tomography scan showing a cystic mass in the right kidney. Mass arising from the amterolateral aspect of the kidney, centered in the medulla; largely necrotic with peripheral firm areas (b and c)

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Figure 2: (a and b) Irregular tumor mass with infiltrative margins. (H and E, ×40; b H and E, ×100); (c) tumor disposed in angulated tubules (H and E, ×100); (d) Focal collection of inflammatory infiltrate consisting of lymphocytes and neutrophils (H and E, ×400)

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Figure 3: (a) Round to oval hyperchromatic cells (H and E, ×400); (b) hobnail pattern of the tumor cells (H and E, ×400); (c) dysplastic changes in the tubules adjacent to the tumor cells (H and E, ×400); (d) normal appearing transitional epithelium at the pelviureteric junction. (H and E, ×100)

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Figure 4: (a) Reactive hyperplasia of the lymph node with tumor deposits in the soft tissue; (b) tumor cells displaying positivity for CK7; (c) positive for High Molecular Weight Cytokeratin; (d) negative for CD10

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Based on these findings, a differential diagnosis of CDC, medullary carcinoma, Gland-forming urothelial carcinoma, mucinous tubular, and spindle cell carcinoma of the kidney was considered. Immunohistochemistry for CD10, CK7, High Molecular Weight Cytokeratin, and p63 was done. Tumor cells displayed diffuse positivity for CK7 and HMWCK and were negative for CD10 and p63 [Figure 4]b, [Figure 4]c, [Figure 4]d. Hence, the diagnosis of CDC was confirmed.

   Discussion Top

CDC is a rare variant of renal cell carcinoma with an aggressive clinical behavior. On extensive PubMed search, <100 cases have been reported in the literature so far.[7] It is histologically distinct from other variants owing to its origin from the collecting duct epithelium which is supported by its location in the renal medulla, architectural similarity to the distal collecting duct tubules, atypical hyperplasia/dysplasia of the collecting duct epithelium adjacent to the neoplasm and immunohistochemical reactivity with Ulex europaeus-1 lectin, peanut agglutinin, and high-molecular-weight cytokeratin (34bE12) similar to collecting duct cells.[2],[3],[4]

CDC can occur at any age but is more common in young males. The average age of onset is 58 years, and 71.6% of the cases show male predilection. Its clinical presentation is nonspecific and may include symptoms of gross hematuria, backaches, weight loss, and a local mass.

Cystic renal masses pose diagnostic dilemma especially when they belong to Bosniak Type II and III, whereas Type I and Type IV are diagnosable on CT very easily. About 10%–15% of renal cell carcinomas can appear as complex cystic lesions of imaging studies. Nonmalignant renal cysts can have a complex appearance on CT as a result of hemorrhage, infection, or inflammation.

The Bosniak criteria were introduced to allow the use of specific CT findings to help separate nonsurgical from surgical cystic masses and guide patient management.[7] These criteria use five separate categories (I, II, IIF, III, and IV). A Bosniak I cyst is a simple, uncomplicated cyst of the kidney. At CT, these cysts have a hairline-thin wall, do not contain calcifications or septations, and do not demonstrate contrast enhancement. These cysts are benign and require no further evaluation.[8] Bosniak II cysts are minimally complicated. They may demonstrate fine calcifications or a short segment of slightly thickened calcification in the cyst wall or septa. These include septated cyst, minimally calcified cyst, infected cyst, and high-density cysts. These are usually benign and require no follow-up. The goal is to avoid surgery in these lesions and to avoid surgical exploration which is usually needed in Type III cysts.

A Bosniak IIF cyst is a cyst that requires follow-up imaging to determine whether it is benign. These lesions may show several thin internal septations without measurable enhancement, a few nodular calcifications, and a smooth thickening of the cyst wall.

Bosniak III cysts are complicated cysts which may contain thick irregular walls and/or septa that demonstrate measurable enhancement. Septations are more numerous than in a Bosniak II cyst. These cysts have a reported 30%–100% chance of malignancy. Radiologically, these cysts cannot be confidently distinguished from a malignant neoplasm. Aside from cystic renal malignancy, the differential diagnosis for a Bosniak III cyst includes multilocular cystic nephroma, mixed epithelial and stromal tumor (MEST), metanephric adenoma, cystic oncocytoma, benign multiloculated cyst, complex septated cyst, hemorrhagic cyst, and renal abscess.[8] However, these cysts should be explored surgically.

Bosniak IV cysts contain enhancing nodular soft-tissue components and are considered malignant until proven otherwise. These cysts show irregularity of the margins and contain solid vascular elements. A small percentage of these lesions may have a benign pathology (e.g., MEST). Surgical resection is recommended. Although the imaging provides the clue to the diagnosis, definitive diagnosis is possible only on histopathological examination.

In our case, a 65-year-old female presented with painless hematuria. On radiological workup, a diagnosis of cystic lesion with uniform wall thickening favoring hydatid cyst was made. On histopathology, the mass turned out tobe a malignant lesion. This emphasizes the role of histopathology in cases where the distinction between a Bosniak II and III cyst based on imaging is difficult. Siegel et al. documented interobserver variability in categorizing Bosniak II and III lesions .[9] This distinction holds importance because category II lesions owing to their benign nature are managed conservatively. Category III, on the other hand, is managed surgically as they are assumed to carry a greater risk of malignancy. There are recommendations to upgrade borderline category II/III cysts especially hyperdense cysts into category III.[10]

The patient presented with a 2-month-old history of painless hematuria. On further workup, no retroperitoneal lymphadenopathy or distant metastasis was noted. This is in contrast to the usually aggressive behavior of this variant with 40% of the patients presenting with metastasis at presentation.[4] Metastasis to distant organs including bone and leptomeninges have been reported thus emphasizing the role of early detection and work up of any cystic solid mass lesion of the kidney involving the medullary area in an old patient.[4]

Based on the histomorphological features, differential diagnosis considered were Medullary Renal Carcinoma, Mucinous Tubular and Spindle Cell Carcinoma of kidney and Gland forming Urothelial Carcinoma and CDC. Mean age at presentation of a medullary carcinoma is 22 years and is usually associated with Sickle cell disease or trait. Rest of the lesions present at an older age. Grossly, CDC and Medullary carcinoma are located in the central region of the kidney. Gland forming urothelial carcinoma may distend the pelvis or may appear as an ill-defined scirrhous mass involving the renal parenchyma, thereby mimicking a primary renal epithelial neoplasm. Microscopically, medullary carcinoma shows solid and reticular pattern. Mucinous tubular and spindle cell carcinoma are composed of tightly packed small elongated tubules in a pale mucinous stroma. CDC shows extensive permeation of the renal parenchyma with angulated tubules and tubulopapillary architecture in a desmoplastic stroma. CDC is characterized by immunohistochemical reactivity for Ulex europaeus-1 and high molecular weight keratin (34betaE12) and is negative for CD10. Medullary carcinoma is nearly always positive for Keratin AE1/AE3, EMA, Low Molecular Weight Cytokeratin and negative for High Molecular Weight Cytokeratin. Mucinous tubular and spindle cell carcinoma show a complex immunophenotype displaying positivity for LMWCK, CK7, CK19 and 34betaE12, Ulex europaeus, and are negative for CD10. Gland forming Urothelial carcinoma shows reactivity for p63, CK7, and CK20.

   Conclusion Top

Cystic renal masses pose a diagnostic challenge especially when they belong to Bosniak type II and III. Although imaging provides a clue to the nature of the lesion, histopathology supported by immunohistochemistry forms the mainstay of diagnosis. Any complex cystic mass of the kidney in an old patient should be carefully evaluated by imaging followed by an imaging-guided biopsy/surgery in cases of indeterminate cysts.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Rumpelt HJ, Störkel S, Moll R, Schärfe T, Thoenes W. Bellini duct carcinoma: Further evidence for this rare variant of renal cell carcinoma. Histopathology 1991;18:115-22.  Back to cited text no. 1
Srigley JR, Eble JN. Collecting duct carcinoma of kidney. Semin Diagn Pathol 1998;15:54-67.  Back to cited text no. 2
Dimopoulos MA, Logothetis CJ, Markowitz A, Sella A, Amato R, Ro J, et al. Collecting duct carcinoma of the kidney. Br J Urol 1993;71:388-91.  Back to cited text no. 3
Foot NC, Papanicolaou GN. Early renal carcinoma in situ detected by means of smears of fixed urinary sediment. J Am Med Assoc 1949;139:356-8.  Back to cited text no. 4
Srigley JR, Moch H. Carcinoma of the collecting ducts of Bellini. In: Eble JN, Sauter G, Epstein JI, Sesterhenn IA, editors. World Health Organization classification of tumours: Pathology and genetics of tumours of the urinary system and male genital organs. Lyon: IARC Press; 2004. p. 33-4.  Back to cited text no. 5
Li M, Vuolo MA, Weidenheim KM, Minsky LS. Collecting-duct carcinoma of the kidney with prominent signet ring cell features. Mod Pathol 2001;14:623-8.  Back to cited text no. 6
Bosniak MA. The current radiological approach to renal cysts. Radiology 1986;158:1-0.  Back to cited text no. 7
Silverman SG, Israel GM, Herts BR, Richie JP. Management of the incidental renal mass. Radiology 2008;249:16-31.  Back to cited text no. 8
9. Siegel CL, McFarland EG, Brink JA, Fisher AJ, Humphrey P, Heiken JP. CT of cystic renal masses: analysis of diagnostic performance and interobserver variation. American Journal of Roentgenology 1997;169: 813–18.  Back to cited text no. 9
Harisinghani MG, Maher MM, Gervais DA, McGovern F, Hahn P, Jhaveri K, et al. Incidence of malignancy in complex cystic renal masses (Bosniak category III): Should imaging-guided biopsy precede surgery? AJR Am J Roentgenol 2003;180:755-8.  Back to cited text no. 10

Correspondence Address:
Varsha Kumar
Department of Pathology, M. L. N. Medical College, Allahabad - 211 002, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_849_16

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Ranjan Agrawal
Indian Journal of Pathology and Microbiology. 2018; 61(3): 309
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