Malignant masquerade: A case report of urachal malakoplakia disguised as urachal tumor

Abstract

Malakoplakia is a rare inflammatory disease that predominantly affects the genitourinary tract, with the urinary bladder being the most commonly involved site. Although its exact pathogenesis remains unknown, it is well-established that the condition is associated with chronic urinary tract infections and immunosuppression. Its presentation often poses a significant diagnostic challenge, as it can closely mimic malignancy. We report a case of a 55-year-old female who presented with lower urinary tract symptom with a palpable hypogastric mass, imaging suspected urachal tumor. A partial cystectomy was performed, which histology confirmed the diagnostic of Urachal Malakoplakia.

Highlights

• •Malakoplakia is a rare granulomatous disease that mimics malignancy.
• •It results from defective phagocytosis, leading to bacterial accumulation.
• •The genitourinary tract, especially the bladder, is the most affected site.
• •Diagnosis relies on histopathology, showing Michaelis-Gutmann bodies.
• •Treatment includes antibiotics, surgery, and immune-modulating therapies.

1. Introduction

Malakoplakia is an unusual granulomatous inflammatory disease of uncertain etiology, first identified in 1902 by Michaelis and Gutmann.¹ This rare disease is more frequently observed in immunocompromised and elderly patients. While it can affect various organs, it was initially described in and predominantly involves the genitourinary tract, with the bladder being the most commonly affected site. While malakoplakia is a benign condition, it often mimics a malignant neoplasm, particularly when a mass-like lesion is present. The gold standard for the diagnosis and treatment of malakoplakia has not yet been established. We report an exceptionally rare case of urachal malakoplakia without bladder involvement. As far as we know, this represents the first reported case of its kind in our country. A comprehensive literature review revealed very few similar cases reported elsewhere.²

2. Case presentation

A 55-year-old female, with a history of diabetes for 3 years, hypercholesterolemia on statin therapy for 2 years, presented to the urology department with dysuria, pollakiuria, urinary urgency and suprapubic pain with a palpable mass in the hypogastric region, evolving in a context of weight loss and fatigue over the past few months.

On physical examination, palpation of the lower abdomen revealed a firm, tender and painless hypogastric mass. Otherwise, there was no pain in lumbar fossae.

The ultrasound showed a heterogeneous hypoechoic mass poorly defined, in contact with the anterior bladder wall, specifically in the area of the urachus, measuring 52 × 35mm (Fig. 1).

Fig. 1.

Sonographic appearance of the urachal mass.

We completed investigations by Uro-CT which confirmed the presence of a heterogeneous mass on the anterior bladder wall with a thickened and irregular wall enhancing after contrast injection, containing heterogeneous liquid, measuring 64 × 58mm, with heterogeneity in the surrounding tissues, likely due to extension or involvement of adjacent fat, without iliac or lumbar aortic lymph nodes (Fig. 2).

Fig. 2.

Uro-CT appearance of the urachal mass. (A: Axial view, B: Sagittal view).

Due to the mass effect exerted by the mass and the difficulty in orienting the diagnosis, a pelvic MRI was requested to precisely detect the presence of an endoluminal growth and any potential infiltration of the bladder wall, which showed a supravesical cystic formation, along the midline, behind the muscular wall, restricting diffusion, with a thickened wall enhanced after injection, measuring 45x40 × 32mm, appearing suspicious, exerting a mass effect on the bladder dome without endoluminal growth (Fig. 3).

Fig. 3.

Sagittal T2-weighted image of the urachal mass.

Cystoscopy revealed no obvious intraluminal growth, with a protruding appearance of the bladder mucosa at the level of the dome (Fig. 4) with hyperemia. The biopsy revealed features of cystitis with no evidence of malignancy.

Fig. 4.

Cystoscopy view showing the mass effect exerted by the mass with hyperemia.

The blood routine analysis revealed a white blood cell count of 7.6 × 10⁹/L with a neutrophil percentage of 84,9 %. Urine routine analysis indicated a bacterial count (BAC) of 1300/μL. The urine culture identified the presence of Escherichia coli.

The patient was thoroughly informed about the provisional diagnosis, the planned surgical procedure, and the potential complications associated with the surgery. Informed consent was obtained accordingly.

The patient underwent laparoscopic partial cystectomy with excision of mass arising from the urachus (Fig. 5) and pelvic lymphadenectomy.

Fig. 5.

Intraoperative images of the mass (A: Trocar placement, B: Laparoscopic view of the mass, C: Laparoscopic view of partial cystectomy, D: Macroscopic view of the specimen).

The final histopathology report confirmed that the excised urachal remnant exhibited features of foamy histiocytes and Michaelis–Gutmann bodies. Notably, there was no involvement of the urinary bladder wall. Histopathological examination revealed no evidence of malignancy.

The postoperative course was without complications, and the patient was released on a prolonged course of ciprofloxacin. The follow-up was uneventful, based on urinalysis, ultrasonography, and serum creatinine levels, showing no evidence of recurrence.

3. Discussion

Malakoplakia, also referred to as Von Hansemann's disease, derived from the Greek words "malakos" meaning "soft" and "plakos" meaning "plaque," was first described by Michaelis and Gutmann in 1902.¹ It is an uncommon inflammatory disease and the exact etiology is still unclear, hypothesized to result defective phagocytosis, attributed to reduced intracellular levels of cyclic guanosine monophosphate (cGMP), the decreased cGMP/cAMP (cyclic adenosine monophosphate) ratio affects the "redox" status of the cell, leading to inadequate bacterial killing. As a result, a granulomatous reaction occurs due to the accumulation of bacterial degradation products, where partially digested bacteria calcify and cluster within macrophages, creating the distinctive Michaelis-Gutmann bodies.³ In addition, the macrophages involved in malakoplakia exhibit elevated levels of immunoreactive α1-antitrypsin, distinguishing it from other inflammatory processes, except for tuberculosis and xanthogranulomatous pyelonephritis. Therefore, an immunohistochemical search for α1-antitrypsin can be valuable in the differential diagnosis.⁴

Malakoplakia predominantly occurs in middle-aged individuals, with a male-to-female incidence ratio of approximately ¼.⁵ The genitourinary tract is involved in approximately 75 % of cases, among these cases, approximately 40 % involve the bladder. Although malakoplakia has also been reported in other sites, including the gastrointestinal tract, retroperitoneum, skin, lungs, brain, adrenal gland, tonsils, conjunctiva, and pancreas. It is commonly observed in patients with immunosuppression, diabetes mellitus, renal transplantation, prolonged corticosteroid therapy, and a history of Escherichia coli infection.⁶

Clinically, bladder malakoplakia has nonspecific clinical symptoms, however, it may manifest with irritative lower urinary tract symptoms (LUTS), including dysuria, pollakiuria, urinary urgency, and hematuria.³ These symptoms can resemble those of cystitis or bladder cancer. In our case, the patient presented with LUTS, although the bladder was not involved, likely due to the proximity of the mass to the bladder. The patient reported also a palpable mass, however, symptoms of urachal involvement were not reported in the literature, given its uncommon occurrence.

The imaging manifestations of this disease are also nonspecific, with most organs developing tumor-like nodules.⁷ Tian J et al., in their analysis of 33 urachal masses, reported that the majority (67 %) were malignant, while 33 % were benign, with only two cases identified as malakoplakia. Computed tomography (CT) plays a crucial role in differentiating benign from malignant urachal masses, with malakoplakia typically presenting as hypodense lesions on CT imaging. Surgical excision remains the definitive treatment for benign urachal masses.⁸ Extended partial cystectomy offers a curative surgical approach for localized urachal cancer. In our case, imaging was more suggestive of malignancy and the mass was evaluated as urachus carcinoma leading to partial cystectomy. The primary treatment for urachal carcinoma is surgical resection, with partial cystectomy being the most common approach.⁹Due to the high risk of recurrence and metastasis, chemotherapy is considered for advanced cases, with regimens like gemcitabine-cisplatin (GP) offering the best survival outcomes⁹.

Currently, its diagnosis is primarily based on pathological findings. In our case, frozen or excisional biopsy was not performed due to the high risk of perforation and implantation in cystic lesions. The mass was diagnosed as malakoplakia following final pathological examination. It is histologically characterized by Von Hansemann-type histiocytes, which are large mononuclear phagocytes which contain basophilic lysosomal inclusion bodies, giving a concentric owl eye appearance, known as Michaelis-Gutmann bodies,¹⁰ they can be seen in the interstitium or cytoplasm of macrophages.¹¹ It is important to note that in the early stages of malakoplakia, Michaelis-Gutmann bodies may not be present. Therefore, their absence does not rule out the diagnosis.¹²

Due to the rarity of this disease, the treatment approach is often empirical in some cases. There are no multicenter randomized controlled trials or evidence-based case reports on medical treatment, and management primarily focuses on maintaining urine sterility.¹³ Antibiotic treatment for malakoplakia can often manage the disease effectively, it has been reported that quinolones, sulfamethoxazole, and rifampicin are effective antibiotics for the condition.¹⁴ However, as the condition progresses, surgical intervention becomes necessary. The duration of antibiotics use depends on the follow-up results of the disease, and when combined with surgery, it can shorten the treatment period. Recently, cholinergic drugs and vitamin C have been shown to enhance macrophage phagocytic activity and boost immune function by influencing oxidative stress levels and elevating the cGMP/cAMP ratio.¹³ The combination of these two drugs with antibiotics has shown a certain degree of efficacy in the treatment of malakoplakia.¹⁵

4. Conclusion

Malakoplakia is a rare chronic granulomatous disease characterized by nonspecific clinical manifestations and a high likelihood of misdiagnosis. It should be considered as a potential differential diagnosis for urachal masses. Urachal malakoplakia may present as a urachal mass associated with lower urinary tract symptoms without concurrent bacterial infection, hematuria, malignancy, or bladder involvement. Its diagnosis relies on histopathological examination. Long-term oral antibiotics, in combination with cholinergic drugs or vitamin C, can be utilized as treatment options for this condition.

CRediT authorship contribution statement

Imad Boualaoui: Writing – review & editing, Validation. Adam El Aboudi: Writing – review & editing, Writing – original draft. Mohammed Ali Mikou: Writing – original draft, Visualization, Data curation. Hamza El Abidi: Writing – review & editing. Salim Ouskri: Writing – review & editing, Writing – original draft, Visualization. Saad Mesbahi: Resources. Ahmed Ibrahimi: Validation, Supervision. El Sayegh Hachem: Validation, Supervision. Nouini Yassine: Validation, Supervision.

Informed consent

The patient's consent was required, voluntary and informed.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflicts of interest

The authors declare that they have no competing interests relevant to the content of this article.