An Unusual Bladder Tumor in a Male Adult

Specimen Type:

Bladder

History:

A 54-year-old male presented with hematuria and underwent transurethral resection of a bladder tumor located in trigone of the bladder. The specimen consists of numerous fragments of pink-tan prostatic tissue in aggregate weighing 7 gm and measuring 2.0 x 2.0 x 0.6 cm. Representative sections were submitted.

Pathologic Features:

Microscopic examination shows numerous orderly distributed glands lined by intestinal type epithelium, conforming to the appearance of the intestinal variant of cystitis glandularis (Fig.1). A minor component of typical cystitis glandularis is also present (Fig. 2). Mucin extravasation is conspicuous (Fig. 3). In some areas, the pools of mucin are rounded and surrounded by compressed mesenchymal cells of the adjacent lamina propria, imparting an appearance that suggests mucinous cysts (Fig. 4). No epithelial cells are present in the extravasated mucin (Fig 5), and the cytologic atypia of the cells lining the intestinal type glands is minimal (Fig 6). There is no definite evidence of infiltration of the muscularis propria by the glands, although they abut the smooth muscle in the specimen (Fig. 7). Immunohistochemically, these cells are positive for both cytokeratins 7 and 20.

Differential Diagnosis:

  • Florid cystitis glandularis of intestinal type with mucin extravasation
  • Villous adenoma of the Urachus
  • Villous adenocarcinoma of the Urachus
  • Adenocarcinoma of the bladder
  • Urothelial carcinoma with glandular differentiation
  • Colon cancer metastasis
  • Metastasis from other sites

Diagnosis:

Florid cystitis glandularis of intestinal type with mucin extravasation

The most common benign epithelial abnormalities of the urinary bladder are the three inter-related entities von Brunn's nests, cystitis glandularis, and cystitis cystica. Cystitis glandularis is usually found in the trigone and bladder neck, as in our cases. It uncommonly poses serious diagnostic problems for the pathologist because the architectural complexity and cytologic atypia in most adenocarcinomas exceeds that seen in cystitis glandularis. However, in our experience, one of the two subtypes of cystitis glandularis, the intestinal variant, is particularly likely to be problematic when florid and associated with extravasation of mucin into the stroma, a phenomenon that has received little comment in the literature.

Microscopically, florid cystitis glandularis of intestinal type with mucin extravasation consists of numerous glands lined by intestinal type epithelium, conforming to the appearance of the intestinal variant of cystitis glandularis. A minor component of typical cystitis glandularis is usually present. Mucin extravasation is often conspicuous. In some areas, the pools of mucin are rounded and surrounded by compressed mesenchymal cells of the adjacent lamina propria, imparting an appearance that suggests mucinous cysts. The differential diagnoses include villous adenoma or adenocarcinoma of the urachus, adenocarcinoma of the bladder with glandular differentiation, and metastatic colonic carcinoma. In favor of a benign interpretation are the absence of epithelial cells in the extravasated mucin, the lack of cytologic atypia of the cells lining the intestinal type glands, a generally orderly distribution of the glands, and their lack of infiltration of the muscularis propria, although they sometime abut the latter.

In our experience establishing the diagnosis of adenocarcinoma of the bladder is most troublesome with urachal lesions. They may be paucicellular and show cytologic atypia insufficient to unequivocally diagnose carcinoma when viewed in isolation from biopsy or curettage material but, clinically and when resected, are clearly adenocarcinomatous. In problematic cases it is important to know the location in the bladder of the unusual glandular tissue, that originating from the intestinal variant of cystitis glandularis usually being from the bladder neck or trigone.

Distinction from a transitional-cell carcinoma with gland differentiation may be difficult because some such cancers have transitional cells at the periphery of glands, analogous to what is seen in typical cystitis glandularis. The glands in the intestinal variant, however, are unassociated with transitional cells. Additionally, many adenocarcinomas of the bladder are of intestinal type; therefore, their individual glands resemble, to some extent, those of the intestinal variant of cystitis glandularis. The distinction between the two processes depends on architectural and cytologic differences between them, but these may be subtle.

An analogy can be made between the distinction of cystitis glandularis with mucin extravasation from adenocarcinoma of the bladder and the distinction between mucin extravasation in benign intestinal lesions and colonic adenocarcinoma. In most mucinous adenocarcinomas, in the bladder and elsewhere, some mucin pools within an adenocarcinoma can be devoid of neoplastic cells, but most have at least a few tumor cells in or around them. The total absence of atypical cells within or at the periphery of the extravasated mucin in our cases, therefore, strongly favors a benign diagnosis. In summary, to diagnose adenocarcinoma, one requires unequivocal malignant cytologic features in cells lining intestinal-type glands or atypical epithelial cells associated with mucin pools.

References:

  1. Young RH, Bostwick DG. Florid cystitis glandularis of intestinal type with mucin extravasation: a mimic of adenocarcinoma. Am J Surg Pathol. 1996;20(12):1462-8.