Urine cytology: Pitfall due to a "remnant" lesion
Michael Chaump MD 1, Tamar Giorgadze MD, PhD 1, Andrew M Schreiner MD 2
1 525 East 68th Street, Room F-766, New York Presbyterian Hospital, Weill Cornell Medical Center, Papanicolaou Cytology Laboratory, New York, NY 10065, USA
2 Department of Pathology, New York Hospital Queens, Flushing, NY 11355, USA
|Date of Submission||05-Jun-2015|
|Date of Acceptance||07-Jun-2015|
|Date of Web Publication||28-Jul-2015|
525 East 68th Street, Room F-766, New York Presbyterian Hospital, Weill Cornell Medical Center, Papanicolaou Cytology Laboratory, New York, NY 10065
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chaump M, Giorgadze T, Schreiner AM. Urine cytology: Pitfall due to a "remnant" lesion. CytoJournal 2015;12:16
A 36-year-old G0 P0 woman presented with complaints of increased urinary frequency and nocturia. She did not report incontinence, dysuria, gross hematuria, or other medical history. Radiologic evaluation showed 2.6 cm irregular, solid and cystic lesion in the superior wall of the bladder, located immediately right of the midline. Cytopathologic findings in voided urine were as shown in [Figure 1].
|Figure 1: Voided urine cytology in a liquid based (ThinPrep) preparation. (a) Large cohesive sheet of glandular epithelium with ragged outline (ThinPrep, Papanicolaou stain, ×100). (b) Strip of benign glandular cells exhibiting eccentric nuclei with retained nuclear polarity (ThinPrep, Papanicolaou stain, ×600). (c) Sheet of glandular epithelium with scant to moderate amount of cytoplasm and round to oval nuclei (ThinPrep, Papanicolaou stain, ×400). (d) Group of cells with granular cytoplasm, fine chromatin, and inconspicuous nucleoli (ThinPrep, Papanicolaou stain, ×600)|
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| » What is your interpretation?|| |
- Cystitis cystica et glandularis
- Endometriosis involving the bladder
- Urachal remnant
| » Additional quiz questions|| |
1. In the fetus, the urachus is a remnant of the connection between the:
- Median umbilical ligament and allantois
- Allantois and yolk sac
- Fetal bladder and the umbilical cord
- Umbilical cord and yolk sac
- None of the above.
2. The epithelium of the inner urachal layer is:
- A and B
- B and C.
3. Cytological features of urachal remnants in urine cytology include:
- Sheets of cells comprised of bland glandular cells
- Strips and clusters of bland glandular cells with polarized, eccentric nuclei
- Smooth nuclear contours with stippled chromatin and inconspicuous nucleoli
- Glandular cells with granular cytoplasm
- All of the above.
Answers to additional quiz questions
1. C; 2. D; 3. E
- During fetal development, the fetal bladder and the umbilical cord is connected by the allantois. During development, the bladder descends and the urachal lumen constricts to form the median umbilical ligament. The urachus may persist as a remnant if this process is incomplete
- Pathological examination is necessary for a diagnosis of the urachal remnant. As described histologically, the urachal remnant has an inner epithelial layer, middle fibroconnective tissue layer, and the outer smooth muscle layer. The lining can be urothelial or columnar epithelium
- Cytological features of urachal remnants include sheets, strips, and clusters of bland appearing glandular cells. These cells have scant to moderate amount of cytoplasm and round to oval nuclei. The nuclear features are also benign appearing with smooth contours, slightly stippled fine chromatin, and inconspicuous nucleoli. Because this is a benign entity, mitotic figures, and apoptotic bodies should not be present.
| » Brief review of the topic|| |
The patient underwent a transurethral resection of the posterior superior bladder wall lesion. The histological examination showed a cystic lesion that involved the bladder lamina propria and muscularis propria. The cyst was lined by stratified cuboidal epithelium without significant cytological atypia or mitoses. The underlying stroma was congested. Also seen were ductal structures lined by cuboidal epithelium sorrounded by muscular walls that were in continuity with the detrusor muscle, consistent with a urachal remnant [Figure 3].
|Figure 3: Histology from the transurethral resection of the posterior superior bladder wall lesion. (a) Cyst involving bladder lamina propria and muscularis propria (H and E, ×100). (b) Cyst lining composed of stratified cuboidal epithelium (H and E, ×400). (c) Ductal structure with a muscular wall in continuity with the detrusor muscle (H and E, ×200). (d) Duct lining composed of cuboidal epithelium (H and E, ×600)|
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Urachal remnants overall are not a common fining in urine cytology. Whereas the radiological and pathological differential diagnosis is broad attention to cytological details can provide a definitive diagnosis.
Cytomorphological features of urachal remnants that can be seen in liquid-based preparation of urine specimens include the following:
- Sheets or clusters comprised of varying numbers of bland appearing cells with scant to moderate amounts of cytoplasm
- Strips of columnar cells with eccentric, polarized nuclei
- Benign appearing nuclei with smooth nuclear contours, finely stippled chromatin, and inconspicuous nucleoli.
Overall, cytological features of urachal remnants in urine cytology may mimic many benign and malignant conditions involving the bladder. High index of suspicion, bland cytology of the glandular epithelial fragments, and clinical-radiological correlation will be helpful in distinguishing this entity from malignant processes and arriving at the correct diagnosis.
Surgical intervention is recommended when a persistent urachus is identified to avoid symptomatic recurrence and complications. Whereas an open procedure has been classically described, laparoscopic approaches to resection offers lower morbidity and mortality.
Focused differential diagnosis of urachal remnants
- Can mimic a mucinous cystic tumor or bladder tumor radiologically 
- Cytomorphological identification relies on the presence of cuboidal or columnar mucin-secreting cells which can also be of intestinal-type 
- Significant atypia and mitoses are only rarely found which also differentiates them from adenocarcinoma 
- Epithelium identified is usually distinguishable from the transitional epithelium seen with urachal remnants. However, both entities may cytologically appear similar if the urachal remnant is lined by columnar epithelium.
Endometriosis involving the urinary tract
- Not a common entity, occurring in approximately 1% of all patients with endometriosis
- Most frequent site of occurrence in the dome of the bladder 
- Cytomorphological analysis of urine will often show hemosiderin laden macrophages or the presence of endometrial cells
- Endometrial cells are identified as honeycombing sheets or as spherules with clusters of stromal cells surrounded by epithelial cells 
- Usually, no nuclear atypia is observed and nucleoli are inconspicuous.
Müllerianosis of the urinary bladder
- Rare lesion that has not been frequently reported in the literature
- Grossly it appears as a polypoid or cystic mass with dark blue or black cysts on cystoscopy
- Cytomorphological features resemble endosalpingiosis, endometriosis or endocervicosis. ,
- Often the diagnosis is preceded by a history of instrumentation or chronic inflammatory insult 
- In liquid-based preparations of urine specimens, variably sized cell clusters and papillary structures are evident
- Cytomorphological analysis shows atypical cuboidal cells with a moderate amount of cytoplasm. The nuclei may be round to slightly irregular with granular chromatin and small nucleoli
- Cytoplasmic vacuoles can be present which may give the cells a signet-ring appearance. ,
Adenocarcinoma of the bladder (including primary bladder adenocarcinoma, urachal adenocarcinoma, and metastatic carcinoma)
Adenocarcinoma of the bladder
- Adenocarcinomas of the bladder or urothelial carcinomas with glandular differentiation are rare in young patients, as are metastatic adenocarcinomas. Histologically, the majority of bladder adenocarcinoma is comprised of glandular structures showing features of colonic adenocarcinoma (enteric type), intracellular mucin (signet cell type), or extracellular mucin (mucinous type)
- Cytomorphological analysis of urine cytology will show glandular cells with cytological atypia and frequent mitoses
- In half of the cases of urothelial carcinoma with glandular differentiation, a second population of malignant cells with morphology consistent with high-grade urothelial carcinoma will be present
- Adenocarcinomas (as well as rarer types of carcinomas) have been described as arising in urachal remnants.  In these cases, cytological features of adenocarcinomas arising in urachal remnants are similar to the other primary and secondary adenocarcinomas that can be encountered in the bladder. 
| » Competing interests statement by all authors|| |
The authors declare that they have no competing interests.
| » Authorship statement by all authors|| |
All authors of this article declare that we qualify for authorship as defined by ICMJE http://www.icmje.org/#author.
Each author has participated sufficiently in the work and takes public responsibility for appropriate portions of the content of this article.
| » Ethics statement by all authors|| |
As this is a quiz case without identifiers, our institution does not require approval from Institutional Review Board (IRB) (or its equivalent).
| » List of abbreviations|| |
MRI - Magnetic Resonance Imaging
IRB - Institutional Review Board.
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[Figure 1], [Figure 2], [Figure 3]