Sonography may be normal and reveal totally nonspecific abnormalities: numerous calcifications often accumulate in the posterolateral regions of the peripheral prostate; increased vascularization is not detectable on current sonography equipment; the echostructure of the prostatic parenchyma is nonhomogenous, alternating between non-systematized hyperechoic strips and hypoechoic zones that sometimes contain pseudonodules and dilated ducts [4].

Faced with a hypoechoic strip in the peripheral zone, differential diagnosis from an underlying neoplasm is impossible and an ultrasound-guided biopsy is required depending on the context. MRI is not indicated for the positive diagnosis of chronic prostatitis, but when it is used to guide a prostate biopsy in a patient with raised PSA levels or to assess disease spread in a known cancer, it usually allows cancer to be distinguished from chronic prostatitis [5].

Granulomatous prostatitis (GP), a benign inflammatory condition of the prostate, is a rare urological disorder [6]. First described by Tanner and McDonald in 1943, it has an incidence of 3.3 % among inflammatory lesions [7]. However, some studies report that a significant percentage of men receiving intravesical Bacillus Calmette-Guérin (BCG) immunotherapy for the treatment of superficial urothelial carcinoma of the bladder develop granulomatous prostatitis [8, 9]. The most commonly reported signs are cystic dilation of the ducts, secondary to stenosis of the ejaculatory ducts, and these can meet with the urethra taking on an appearance of cavitation [10–11]. It is generally combined with macro calcifications [6, 7]. Sonography demonstrates single or multiple hypoechoic nodules, localized to the peripheral zone. Since it has a similar clinical presentation and transrectal ultrasound (TRUS) appearance to that of carcinoma of the prostate (CaP) [12, 13] and is associated with an increase in serum prostate-specific antigen (PSA), BCG-induced GP may be mistaken for CaP [14–18].