Pathologic Quiz Case: A Woman With Chronic Pelvic Pain

A 36-year-old gravida 2, para 2 woman with a history of 2 cesarean sections presented with chronic pelvic pain. On physical examination, a tender nodule was palpated anterior to the uterus. She underwent a transabdominal pelvic ultrasound, which revealed an immobile, 1.4-cm, mural-based nodule in the posterior wall of the bladder at the level of the trigone (Figure 1). The uterus, ovaries, and adnexa were unremarkable. Endoscopically guided bladder biopsies were performed, and the specimens consisted of multiple irregularly shaped fragments of gray-white-brown rubbery tissue that measured 2.5 × 1.8 × 0.3 cm in aggregate.Microscopic examination revealed extensive involvement of the bladder by mucous glands that penetrated into the muscularis propria of the bladder wall (Figure 2). These glands were haphazardly arranged, and many had expanded into mucus-filled cysts (Figure 3). The lining of the cysts ranged from a single layer of columnar cells with abundant pale cytoplasm to ciliated cuboidal and flattened cells (Figure 4). There was no nuclear atypia or mitotic activity. There were focal areas that contained ruptured cysts, with extravasation of mucin into the muscularis propria. The stroma that surrounded these glands was edematous and contained an acute and chronic inflammatory infiltrate.What is your diagnosis?Endocervicosis of the urinary bladder is a rare, benign lesion that is believed to be of mullerian origin and is usually an incidental histologic finding. The term endocervicosis is used to refer to the mucinous or endocervical variant of endometriosis.1 In 1992, Clement and Young1 were the first to describe endocervicosis of the urinary bladder. They described 6 cases in women aged 31 to 44 years with symptoms that included urinary complaints (5 cases) and pelvic pain (1 case). Each patient had a 2- to 5-cm mass located in the posterior wall or posterior portion of the dome of the urinary bladder. Histologic examination revealed extensive involvement of the bladder muscularis propria and lamina propria by benign-appearing endocervical-type glands, which were often cystically dilated and filled with mucin. Glandular rupture and mucinous extravasation were noted, with associated reactive changes. The cells that lined these glands ranged from columnar with abundant cytoplasm to flat or cuboidal. Many cells were ciliated. Nuclear atypia and mitotic activity were not prominent.1 Several additional patient series and case reports have been published with similar historical, radiologic, and microscopic findings.2–4Endocervicosis of the urinary bladder is believed to be an endocervical analogue to endometriosis. Associated endometriosis and endosalpingiosis have been noted in several cases. Although the histogenesis is not known, a mullerian origin is suggested by the following: occurrence only in women of reproductive age, location in the posterior bladder wall, frequent association with endometriosis and endosalpingiosis, and a questionable association with previous cesarean section.12 Many authors, therefore, prefer the term mullerianosis with a designation of the subtype (endocervical, endometrial).24The differential diagnosis of endocervicosis includes several benign and malignant conditions. Benign entities to consider include cystitis glandularis, cystitis cystica, nephrogenic adenoma, and urachal remnants. Unlike endocervicosis, in which glands penetrate into the muscularis propria and the lining cells may contain cilia, cystitis cystica and cystitis glandularis involve the lamina propria only and do not contain ciliated epithelium.1–5 Nephrogenic adenoma can be distinguished from endocervicosis by the presence of small tubules with hobnail cells and the absence of mucinous epithelium.235 Urachal remnants, in contrast to the predilection of endocervicosis for the posterior bladder, occur in the anterior wall or apical portion of the dome. Their histologic features include a single canal with nonciliated mucinous epithelium, surrounded by layers of fibrous tissue, smooth muscle, and adventitia.15 Of course, when confronted with a bladder mass lesion composed of adenomatous epithelium, one has to consider adenocarcinoma. However, this condition can usually be excluded under the following circumstances: absence of an associated adenocarcinoma of the endocervix, lack of nuclear atypia and mitotic activity, and a benign clinical course.2–4In summary, endocervicosis of the urinary bladder is a benign mass lesion that occurs in reproductive-age women, is situated in the posterior bladder, and is composed of benign endocervical-type glands that penetrate into the muscularis propria. It is important that this lesion be recognized and not misdiagnosed as a malignant neoplasm.