Older Male with Mucin Within The Bladder Wall

Specimen Type:

Bladder

History:

A 61-year-old man underwent partial cystectomy for adenocarcinoma of the bladder. Representative cross-sections were submitted.

Pathologic Features:

Sections revealed a cystic tumor with extrusion of cysts contents characterized by abundant extracellular mucin with mucin dissection into soft tissue (Fig.6.1-6.2). The glands displayed marked nuclear and architectural atypia; calcifications were present within the mucin pools (Fig.6.3). There appeared to be discrete nests of tumor within the lamina propria (Fig.6.4).

Differential Diagnosis:

  • Urachal adenocarcinoma
  • Nonurachal bladder adenocarcinoma
  • Cystitis glandularis (Fig. 6.5)

Urachal adenocarcinoma: The separation of urachal from nonurachal adenocarcinoma requires correlation of clinical and pathologic findings (Table 1). Adenocarcinoma of the urachus occurs mostly in adults, with a predominance of men over women (1.8:1). Intestinal metaplasia of the urachal epithelium is the favored mechanism accounting for the preponderance of adenocarcinomas of the urachus. Under the microscope, the most frequent histologic appearance is mucinous (colloid) carcinoma with nests and single cells appearing to float in pool of extracellular mucin. The cells have signet ring cell or columnar cell morphology. The next most frequent pattern is enteric adenocarcinoma and the most uncommon pattern is linitis plastica-like signet ring cell carcinoma. Some authors report a better prognosis for urachal than for nonurachal adenocarcinoma, while others have found no difference or a worse prognosis.

Nonurachal bladder adenocarinoma: This is the most frequent primary bladder adenocarcinoma with a 2.6:1 male to female sex ratio. Most cases arise from intestinal metaplasia of the urothelium. Cystitis glandularis is present in 14% to 67% of patients. There are 6 variants of adenocarcinoma of the urinary bladder (Table 2). The prognosis for this tumor is poor.

Cystitis glandularis (Fig.6.5) HE 100X: Cystitis glandularis is a lesion that evolves from and merges with von Brunn’s nests. Cystitis glandularis is so common that it may be considered a normal feature of the vesical mucosa. However, it occasionally forms irregular, rounded, or nodular elevations of the mucosa. Under the microscope, the lesion is composed of glands in the lamina propria, which are lined by cuboidal to columnar cells surrounded by one or more layers of urothelial cells (typical type). The less frequent intestinal type is characterized by tall and columnar lining cells with obvious mucin production. Cystitis glandularis usually poses no diagnostic problem, but occasional cases are difficult to distinguish from adenocarcinoma; more particularly for the intestinal type, especially when mucin extravasates into the stroma. An irregular haphazard arrangement of glands in the deeper lamina propria and cytologic atypia should raise the suspicion of adenocarcinoma.

Diagnosis:

Urachal adenocarcinoma in situ.

Key Features:

  • Correlation of clinical and pathologic findings (Table 1)
  • Cysts lined by mucinous epithelium
  • Pronounced nuclear and architectural atypia
  • Coexistence of abundant mucin extravasation
  • Absence of destructive invasion
  • Specimens must be extensively sampled and the pathologist must see no evidence of invasion

Table 1: Criteria to distinguish Urachal from non-Urachal Adenocarinoma

Epicenter in bladder wall (not mucosa)
Location in bladder dome
Primary involvement of muscle or deeper structures
Presence of a suprapelcic mass
Sharp demarcation between tumor and normal surface epithelium
An intact or ulcerated epithelium
Absense of cystitis cystica or glandularis or internal metaplasia in urothemlium
Presence of urachal remnants
Other primary sites excluded

Table 2: Different histologic types of Adenocarinoma of the Urinary Bladder

Histologic Type Pathologic Findings
Adenocarcinoma NOS Tumor does not resemble another recognized
Enteric Pseudostartified columnar cells forming glands, often with central necrosis, resembling colonic adenocarnimoa
Mucinous (collid) Single or nested tumor cells appearing to float in the extracellular mucin
Signet ring cell Signet ring cells diffusely infiltrating the bladder
Clear cell Papillary and tubular structures with cytologic features similar to mesonephric adenocarinoma of the female genital system
Mixed Findings of 2 or more of the described patterns

References:

  1. Stenhouse G, McRae D, Pollock AM. Urachal adenocarcinoma in situ with pseudomyxoma peritonei: a case report. J Clin Pathol. 2003 Feb;56(2):152-3.
  2. Cheng L, Montironi R, Bostwick DG. Villous adenoma of the urinary tract: a report of 23 cases, including 8 with coexistent adenocarcinoma. Am J Surg Pathol. 1999 Jul;23(7):764-71.
  3. Paul AB, Hunt CR, Harney JM, et al. Stage 0 mucinous adenocarcinoma in situ of the urachus. J Clin Pathol. 1998 Jun;51(6):483-4.
  4. Young RH, Bostwick DG. Florid cystitis glandularis of intestinal type with mucin extravasation: a mimic of adenocarcinoma. Am J Surg Pathol. 1996 Dec;20(12):1462-8.
  5. Grignon DJ , Ro JY , Ayala AG , et al. Primary adenocarcinoma of the urinary bladder. A clinicopathologic analysis of 72 cases. Cancer. 1991 Apr 15;67(8):2165-72.