RESUMO
BACKGROUND: Urachal carcinoma is an uncommon neoplasm associated with poor prognosis. CASE PRESENTATION: A 45-year-old man was admitted with complaints of abdominal pain and pollakisuria. A soft mass was palpable under his navel. TC-scan revealed a 11 x 6 cm tumor, which was composed of a cystic lesion arising from the urachus and a solid mass component at the urinary bladder dome. The tumor was removed surgically. Histological examination detected poor-differentiated adenocarcinoma, which had invaded the urinary bladder. The patient has been followed up without recurrence for 6 months. CONCLUSION: The urachus is the embryological remnant of urogenital sinus and allantois. Involution usually happens before birth and urachus is present as a median umbilical ligament. The pathogenesis of urachal tumours is not fully understood. Surgery is the treatment of choice and role of adjuvant treatment is not clearly understood.