Background: Urachal masses observed in adults should be considered malignant unless they are confuted. It is very difficult to differentiate between malignant or benign lesions, including especially calcified foci and solid areas. Case Report: Our case was a 63-year-old male patient who was diagnosed as Behçet s Disease 26 years ago. Upon clinical examination, he was also diagnosed with adenocarcinoma of prostate. He was examined by computerized tomography to define the stage of prostatic adenocarcinoma. The existence of a hypodense multiseptated cystic lesion with irregular margins and solid areas located between anterosuperior of bladder and umbilicus was reported. Hence, the lesion was evaluated as urachal carcinoma and locally advanced prostate cancer by the urooncology council. Resection of the mass, partial cystectomy and pelvic lymphadenectomy were performed as one of the surgical approach options in urachal carcinoma. After pathological examination, the mass was diagnosed as malakoplakia and metastasis of prostate adenocarcinoma was also detected in the right obdurator lymph nodule. In the literature, case reports of urachal malakoplakia are extremely rare. It is also interesting to note the absence of specific clinical symptoms for the urachal mass and the existence of concomitant adenocarcinoma in our case. Conclusion: Malakoplakia can only be diagnosed by pathological examination. Particularly, urachal malakoplakia should also be taken into consideration in the differential diagnosis of lesions which include solid areas and are located in the urachus. Keywords: Michaelis Gutmann bodies, urachal malacoplakia, urachal malacoplakia mimicking cancer