Enterobius vermicularis (E. vermicularis), also called pinworm or threadworm, is a widespread parasitic infection that has infected approximately 40 million individuals in the United States. However, the infection is rarely seen in the adult population. An atypical presentation of Enterobius vermicularis (E. vermicularis) infection has been reported previously in children and infants. However, there are no previous reports of this infection among adults in the Middle East. We present a case of a 30-year-old Saudi male patient who presented with significant weight loss, diarrhea, and vomiting. A colonoscopy revealed E. vermicularis in the cecum. The patient received one dose of oral albendazole 400 mg and then a repeat dose in two weeks based on his colonoscopy findings. The patient was seen in an outpatient clinic and reported complete resolution of postprandial vomiting. Asking about risk factors if there is any contact with contamination is essential. In addition, colonoscopy and stool analysis may also be considered to confirm the diagnosis. However, future studies investigating the incidence and risk factors of this infection are warranted as similar studies reporting this infection in Saudi Arabia are limited. Proper diagnosis and treatment are also essential to prevent complications of the infection.

Background: Malakoplakia is a rare chronic granulomatous inflammatory disorder characterized by defective macrophage phagolysosomal activity and accumulation of Michaelis–Gutmann bodies on histopathology. It occurs predominantly in immunocompromised individuals and may mimic infectious, inflammatory, or neoplastic processes, creating significant diagnostic challenges. We describe four cases of malakoplakia occurring in distinct immunocompromised states and review the published literature to better characterize its clinical spectrum, management, and outcomes. Methods: We conducted a retrospective case series of four patients diagnosed with histologically confirmed malakoplakia at our institution. Cases occurred in the setting of liver transplantation, kidney transplantation, relapsed acute myeloid leukemia, and ulcerative colitis treated with immunosuppressive therapy. A literature review was performed using PubMed and Google Scholar to identify published cases of malakoplakia in immunocompromised hosts. Demographic, clinical, microbiological, therapeutic, and outcome data were extracted and analyzed descriptively. Results: Four patients with malakoplakia involving the gastrointestinal tract or renal allograft were identified. Clinical presentations ranged from incidental endoscopic findings and tumor-like colonic masses to recurrent bacteremia and graft dysfunction. Histopathologic examination demonstrated characteristic Michaelis–Gutmann bodies in all cases. Management included antimicrobial therapy, observation, and surgical intervention when necessary. Two patients achieved complete clinical and histologic resolution, one required transplant nephrectomy because of persistent allograft infection, and one died from progressive acute myeloid leukemia. Combined with 48 cases identified in the literature, 52 patients were analyzed. The gastrointestinal tract was the most frequently affected site (76.9%), followed by the genitourinary tract (19.2%). Malignancy (32.7%), solid-organ transplantation (26.9%), and autoimmune disease (21.2%) were the most common underlying conditions. Conclusions: Malakoplakia should be considered in the differential diagnosis of mass lesions, persistent infections, and inflammatory lesions in immunocompromised patients, particularly those with malignancy or receiving immunosuppressive therapy. Early histopathologic diagnosis is essential to distinguish malakoplakia from malignancy and guide appropriate management. Our findings highlight the heterogeneous clinical manifestations and outcomes of this uncommon condition and emphasize the importance of multidisciplinary evaluation in affected patients.