41

The Korean Journal of Pathology2008; 42: 41-4

Xanthogranulomatous inflammation of the urachus is a very rare benign chronic inflammatorydisease of an unknown etiology. Herein we report a case of a 31-year-old woman who com-plained of lower abdominal pain and dysuria. Cystoscopy revealed a bullous change at thedome of the urinary bladder. MRI revealed a cystic mass above the bladder dome that extend-ed to the umbilicus. A partial cystectomy with urachal resection was performed. Pathologicalexamination revealed xanthogranulomatous urachitis combined with bullous cystitis.

Key Words : Xanthogranulomatous; Inflammation; Urachus; Cystitis

Ji Eun Kwak∙∙Han-Seong KimMee Joo∙∙Sun Hee ChangSang Hwa Shim∙∙Je G. Chi In Rae Cho1

41

Combined Xanthogranulomatous Urachitis and Bullous Cystitis

- A Case Report -

41 41

Corresponding AuthorHan-Seong Kim, M.D.Department of Pathology, Inje University, Ilsan PaikHospital, 2240 Daewha-dong, Ilsan-gu, Goyang411-706, KoreaTel: 031-910-7142Fax: 031-910-7139E-mail: hs-kim@ilsanpaik.ac.kr

Departments of Pathology and 1Urology,Inje University Ilsan Paik Hospital,Goyang, Korea

Received : July 12, 2007Accepted : September 14, 2007

The urachus is a vestigial remnant of the embryonic allantoicduct, which extends from the dome of the bladder to the umbili-cus. The tubular urachus normally involutes before birth andremains as a fibrous band with no known function. However,persistence of an embryonic urachal remnant can give rise tovarious clinical problems, not only in infants and children, butalso in adults. Urachal carcinoma and infected urachal cysts arethe most frequently reported urachal lesions. Xanthogranulo-matous urachitis is a very rare entity and only a few cases havebeen reported. We report here on a case of xanthogranuloma-tous urachitis with combined bullous cystitis and we discuss itshistopathologic and ultrastructural features.

CASE REPORT

A 31-year-old woman presented with abdominal pain, uri-nary frequency and dysuria for 3 months, and all these problemshad developed after a normal full term delivery. Physical exam-ination detected a palpable mass in the suprapubic area. No ab-

normal findings were detected on the routine serologic findings.The urinanalysis showed a trace of proteinuria and hematuria.Cystoscopic examination showed bullous protrusions of the blad-der mucosa (Fig. 1A). MRI of pelvic cavity revealed a singlecystic mass with peripheral enhancement. The mass originatedfrom the urachus and it involved the urinary bladder dome andit extended up to the umbilicus (Fig. 1B). The urachus, includ-ing the mass and a cuff of the bladder dome, was resected. Thepatient has been in good health with no recurrences for two yearsafter the operation. Grossly, the cystically dilated urachus mea-sured 7×3×2 cm. The cyst was filled with yellowish greasysubstance (Fig. 2A). Microscopically, the cyst contents consist-ed of xanthogranulomatous exudate. The walls of the urachusand the urinary bladder were infiltrated with inflammatory cells.The epithelial lining of the urachal remnant was lost. The maincells of the urachal mass were foamy histiocytes with a smallproportion of lymphocytes and eosinophils (Fig. 2B). No organ-isms were seen on the Gram, GMS, and PAS staining. The xan-thogranulomatous inflammation also involved the perivesicaladipose tissue and the entire urinary bladder wall; this extend-

42 Ji Eun Kwak∙Han-Seong Kim∙Mee Joo, et al.

Fig. 1. (A) Cystoscopic examination shows bullous masses on the surface of urinary bladder (arrows). (B) Computed tomography revealsa cystic mass originating from the dome of the urinary bladder and extending to the umbilical level (between arrows).

A B

Fig. 2. (A) The urachal mass extends from the dome of urinary bladder (arrow indicates partially resected bladder wall) up to the obliter-ated median umbilical ligament (arrowhead). (B) Sheets of foamy histiocytes and mixed inflammatory cells are noted in the xanthogranu-lomatous areas. (H&E, ×200) (C) Xanthogranulomatous cystitis. Xanthogranuloma splits the detrusor muscle layers and creates sub-mucosal mass (arrows). Adjacent mucosa shows edematous bullous cystitis (arrowheads). (H&E, ×10) (D) Ultrastructural study revealsnumerous histiocytes with electron lucent multiple droplets.

C D

BA

Combined Xanthogranulomatous Urachitis and Bullous Cystitis 43

ed up to mucosal surface, causing xanthogranulomatous bullouscystitis with surface erosion (Fig. 2C). On the ultrastructuralexamination, multiple electron lucent multiple droplets with-out limiting membrane were noticed in the histiocytes (Fig. 2D).The size of the droplets was 0.5-2.0 m in their maximumdiameters.

DISCUSSION

Urachus-derived lesions can be categorized as congenital oracquired.1 A congenital patent urachus is derived either fromthe persistence of an open lumen or the failure of the bladder todescend into the pelvis. In patient with acquired disease, theurachus closes normally after birth, but it partially reopens underpathologic conditions. Acquired urachal disorders include um-bilical urachal sinus, vesicourachal diverticulum, urachal cystand alternating sinus.1 Urachal tract remnants that abnormallyremain patent are subject to infection. These infected remmantsare frequently confused with a wide spectrum of midline intra-abdominal or pelvic inflammatory disorders on clinical exami-nation, or they are confused with malignant tumors.2-4

The present case describes typical histopathologic and ultra-structural features of xanthogranulomatous urachitis. Xantho-granulomatous lesions are rare forms of chronic mixed inflam-matory processes that are characterized by the presence of lipid-laden histiocyte aggregation and mass formation. Such lesionshave been described in many other sites such as kidney, urinarybladder, gallbladder, appendix, mandible, retroperitoneum, thirdventricle, choroid plexus, orbit, vagina, lung, stomach, pericardi-um and ovary.5 Urinary tract involvement is well documentedand most commonly as xanthogranulomatous pyelonephritis.Several cases of xanthogranulomatous cystitis have also beenreported.5 Yet xanthogranulomatous involvement of the urachushas been rarely reported6-9 and most of these articles discussedthe clinical and radiological features without description of thehistopathological or ultrastructural findings. According to thosestudies, the clinical and radiological findings of xanthogranulo-matous urachitis were similar to urachal carcinoma and so mak-ing the correct differential diagnosis of solid urachal massesshould be needed.

The ultrastructural features of xanthogranulomatous lesionare not well known. The greater the content of the unsaturatedfatty acid and the higher the degree of unsaturation, the moreelectron dense lipid are seen because that lipid tend to betterbind to osmium.10 Thus, the appearance of the lipid droplets in

the present case suggests that these lipid droplets in xanthogranu-lomatous inflammation are formed of saturated fatty acids, whichexplains their resemblance to the neutral fat (triglyceride) dropletsaccumulated in the hepatocytes.

The pathogenesis of xanthogranulomatous inflammation isnot well known. Defective lipid transport, immunological dis-orders, low virulent infections, reactions to specific infectiousagents and lymphatic obstruction have been proposed as puta-tive mechanisms.11 McVey and McMahon suggested that xan-thogranulomatous inflammation is related to a longstanding orrecurrent inflammatory process.12

Additionally, the present case was combined with xanthogran-ulomatous bullous cystitis. Xanthogranulomatous cystitis isalso rare. It was first described for in 1932 by Wassiljew andsince then only about 20 cases have been reported.13 The loca-tion was mainly at the dome of the urinary bladder or near thedome. To the best of our knowledge, there have been no report-ed cases of combined xanthogranulomatous urachitis and bul-lous cystitis.

In conclusion, xanthogranulomatous urachitis should be in-cluded in the differential diagnosis of urachal masses. Becauseof the lack of specificity for radiological methods used in mak-ing the differential diagnosis of solid or cystic urachal masses,careful pathological study is very helpful to optimize the surgi-cal approach and to avoid unnecessary radical surgery.

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