Striated muscle in the biopsy specimen of the prostate

We had a chance to see striated muscle fibers in the biopsy specimen of the prostate. We examined the prostate specimens of autopsied cases and biopsy specimens. The distribution of striated muscle fibers was studied with an immunohistochemical method for myoglobin to obtain their anatomical distribution in detail. We showed that the striated external sphincter muscle fibers were present in the peripheral zone of the prostatic gland (9.1%). Therefore, if striated muscle fibers are found in biopsy specimens of prostatic cancer, pathologists and urologists should not diagnose simply that the cancer invades beyond the prostatic capsule.