Imaging of the Bulbourethral (Cowper) Gland: Abnormalities and Differential Diagnosis

Normal Cowper glands and ducts are imperceptible at imaging. However, abnormalities of the Cowper glands and ducts are in-creasingly seen owing to increasing use of cross-sectional imaging. The authors present a comprehensive review of the normal anatomy of the Cowper glands and ducts and the clinical and imaging findings of conditions that affect them in an effort to help lead to appropriate diagnosis and management. A Cowper duct syringocele is a congenital or acquired dilatation of the Cowper duct in the bulb of the corpus spongiosum. Retrograde urethrography is the standard test to diagnose a communicating (open) Cowper duct syringocele, and MRI is used for further morphologic assessment. Cowperitis refers to inflammation of the gland and/or duct, and recurrent cowperitis is usually associated with an underlying syrin-gocele, a urethral fistulous connection to the Cowper gland, or a perianal fistula. MRI allows detection of the underlying structural abnormality and the superimposed inflammation. Cowper stones are typically radiopaque and are found in both the Cowper gland and duct. A Cowper gland hemorrhagic cyst may be incidentally detected at MRI of the prostate, and follow-up MRI may be re-quired to ensure evolution of hemorrhage and exclude an underlying neoplasm. Cowper gland carcinoma is rare and includes adeno-carcinoma and adenoid cystic carcinoma subtypes. Transperineal US may be used for initial evaluation and CT and/or MRI are necessary for further characterization and staging. Cowper gland hyperplasia is a rare entity with few previous reports that may be incidentally detected at imaging and may mimic malignancy.