Bladder Mass in an Elderly Male

Specimen Type:

Bladder

History:

A 70-year-old man presents with macroscopic hematuria. Cystoscopy showed a small mass in the right wall of the bladder.

Pathologic Features:

Gross description: Received is an irregular fragment of hyperemic pink tan tissue measuring 0.4cm in greatest dimension. The specimen was submitted in one cassette.

Sections reveal complex exophytic papillae (Fig 1, 2) with formation of numerous microcysts (Fig 3). The microcysts contain blue mucin and eosinophilic material (Fig 4, 5). The epithelium shows variation in thickness, with more than 7 layers (Fig 5) in some areas. No invasion is identified. The cells show slightly enlarged nuclei and nucleoli are inconspicuous (Fig 6).

Differential Diagnosis:

  • Florid polypoid cystitis cystica or cystitis glandularis (Fig 7)
  • Nephrogenic metaplasia (Fig 8)
  • Adenocarcinoma (Fig 9)
  • Papillary urothelial carcinoma with microcyst formation

Florid polypoid cystitis cystica or cystitis glandularis: Both Cystitis cystica and cystitis glandularis are thought to arise from Von brunn’s nests, and are common findings in the bladder; but florid type is uncommon. In the lamina propria, there are numerous cysts lined by cuboidal or flattened urothelium and filled with eosinophilic material (cystitis cystica) or numerous glands lined by cuboidal to columnar cells (cystitis glandularis). These two lesions can coexist, and either of them may predominate.

Nephrogenic metaplasia: Nephrogenic metaplasia is most common in the bladder but may involve the urethra, ureter and renal pelvis. Most patients have a history of an operative procedure or one or more irritants, including calculi, trauma, and cystitis. It is usually 1cm or less in diameter and single, but exceptions occur. Although tubular pattern is the most common, polypoid, papillary and cystic patterns are also seen. The tubules appear as small, round, hollow acini reminiscent of renal tubules. The tubules, cysts, and papillae are lined by flattened, cuboidal or low columnar cells with scant cytoplasm, and hobnail cells are appreciated in up to 70% of the cases. Nuclear abnormalities are uncommon and, when present, appear reactive or degenerative.

Adenocarcinoma: Primary adenocarcinoma of the bladder accounts for less than 1% of bladder cancers. Diagnosis is based on the similar criteria as applied in other sites. Stroma infiltrating is a gold standard. When invasion is not present, especially in biopsy specimen, diagnosis may be suspected if marked cytologic atypia is visualized.

Papillary urothelial carcinoma with microcyst formation: Papillary growth of urothelium lined by more than 7 layers, showing mild to severe cytologic abnormalities. Microcyst formation in urothelial carcinoma is rare.

Diagnosis:

Noninvasive Grade 1 (of 3) papillary urothelial carcinoma (microcystic variant)

Key Features:

  • Complex branding papillae lined by urothelium with more than 7 layers at least focally
  • Mild cytologic atypia—slightly enlarged nuclei, nucleoli is not prominent
  • Numerous microcysts present within the thickened urothelium

Comment: The tumor consists of complex branching papillae lined by urothelium with the formation of microcysts, containing mucin and eosinophilic material. The presence of numerous cysts and minimal cytologic abnormalities raises the concern for a benign process--florid cystitis cystica and glandularis, or nephrogenic metaplasia. Identification of the cysts only within the epithelium rather than in the lamina propria argues against these possibilities. In addition, despite extensive cyst formation, typical urothelium lining the papillae is seen at least focally, providing another clue. Moreover, complex branching papillae is usually not expected in these benign processes. Adenocarcioma is another consideration, but the lining cells are columnar rather than urothelial, allowing the separation.

When the cysts predominate, awareness of this variant may be essential in establishing the diagnosis, particularly in a biopsy specimen. Microcystic variant of urothelial carcinoma is rare, with about 20 cases documented in the literature. This variant has been reported in the bladder and renal pelvis, and is associated with high-stage and high-grade bladder tumors and with other primary tumors, especially of the colon. According to one study, of 12 cases, six patients had a second primary tumor, three had a colon carcinoma, one had a villous adenoma of the caecum, one had a locally advanced carcinoma of the prostate and the remaining one had a squamous cell carcinoma of the uterine cervix. This study suggests the need to screen these patients for asymptomatic tumors of colon.

References:

  1. Radopoulos D, Kalyvas K, Kotakidou R, Panagiotopoulou K, Katsikas V, Papathanasiou M. Case report: microcystic transitional cell carcinoma of the urinary bladder. Int Urol Nephrol. 2005; 37 (2):291-3.
  2. Paz A, Rath-Wolfson L, Lask D, Koren R, Manes A, Mukamel E, Gal R. The clinical and histological features of transitional cell carcinoma of the bladder with microcysts: analysis of 12 cases. Br J Urol. 1997 May;79(5):722-5.
  3. Young RH, Zukerberg LR. Microcystic transitional cell carcinomas of the urinary bladder. A report of four cases. Am J Clin Pathol. 1991 Nov; 96(5):635-9.
  4. Leroy X, Leteurtre E, De La Taille A, Augusto D, Biserte J, Gosselin B. Microcystic transitional cell carcinoma: a report of 2 cases arising in the renal pelvis. Arch Pathol Lab Med. 2002 Jul;126(7):859-61.