Infarct of the prostate gland - Experience on needle biopsy specimens

Prostatic infarcts are uncommon and in the past have only been reported on transurethral resections of the prostate. We reviewed 13 consults and 2 non consult cases of needle biopsies showing prostatic infarcts from two instit utions. The incidence of infarcts on biopsy were 2 in 2958 (0.07%) and 1 in 108,586 (0.0009%) in our nonconsult cases. Men averaged 71 years of age (r ange, 57-84 yrs). No relationship was seen with histories of hypertension, diabetes, atherosclerotic coronary vascular disease, recent surgery, and st eroid use. Four of 12 men with available information had acute urinary rete ntion, with markedly enlarged prostates in three (90 cc, 92 cc, 94 cc); two of these men had hematuria. An additional two men also had large glands (8 4 cc, 150 cc). one also with hematuria. Of eight men without acute urinary retention, three had sudden prostate specific antigen (PSA) rises (increase s of 199 ng/mL, 219 ng/mL, 287 ng/mL). Infarcts were usually an isolated fo cus on one core and varied from 1 mm to 11 mm (mean, 6.3 mm). Six cases sho wed earlier-aged infarcts with coagulative necrosis and recent hemorrhage a nd six showed intermediate-aged infarcts with reactive stroma and epitheliu m without necrosis. In the remaining three cases, there were remote infarct s characterized by replacement of the stroma by dense fibrosis with metapla stic glands. Adjacent tissue revealed reactive nests of immature squamous m etaplasia in 14 of 15 cases with visible nucleoli (12 cases), squamous atyp ia (7 cases), and mitoses ranging from 1-10 (7 cases). Pathologists sent in 10 of 13 consult cases (77%) for problems with interpretation of the infar cts; remaining consults had other pathology of concern. One case was misdia gnosed as urothelial cancer. Features helpful in recognizing infarcts' beni gn nature were cyst formation containing cellular debris with or without ne utrophils (73%), corpora amylacea (20%), and rings of collagen around squam ous islands (40%). Infarcts are typically, although nut exclusively, found in large prostates and may result in sudden rises in serum PSA. Infarcts' d istinctive histology must be recognized and distinguished from necrosis res ulting from infection and prior cryotherapy, as we have seen such misdiagno ses. Pathologists' awareness of prostatic infarcts on needle biopsy and the ir potential for atypical histology can prevent the misdiagnosis of cancer.