Contributed by Hannah Kastenbaum, MD and Agnes K. Liman, MD
The patient is a 68 year old Caucasian male with COPD and left heart dysfunction who presented with a longstanding history of urinary urgency, frequency, and nocturia. He was diagnosed with high grade bladder outlet obstruction, but had a negative cystoscopic examination. Laboratory evaluation was remarkable for a prostate-specific antigen (PSA) of greater than 40 ng/mL, an increase from 32 ng/mL a year previously.
A bone scan showed no lesions and computed tomography showed an enlarged heterogeneous prostate exerting mass effect on the base of the bladder. The patient then underwent needle biopsies of the prostate.
Core biopsies from base, mid-portion, and apex of both the right and left prostate, were examined and revealed an infiltrate of cells with a moderate amount of pale eosinophilic cytoplasm and enlarged nuclei with single prominent nucleoli. The cells formed occasional acinar structures without basal cells, prominent sheets of cells, as well as infiltrating single cells. Some of the neoplastic cells showed clearing and vacuolization of the cytoplasm and compression of the nucleus with a signet-ring appearance. A slide processed with the PIN1 immunohistochemical cocktail (dual alpha-methylacyl co-enzyme A racemase and K903) showed weak positive staining with AMACR and lacking of basal cells around the neoplastic infiltrate.
The patient later underwent open radical retropubic prostatectomy with bilateral lymph node dissection. He had never been treated for his prostate neoplasm.
Gross examination revealed a 62 gram prostate with attached seminal vesicles and vasa deferentia. The prostate gland was 5 x 4.5 x 4.5 cm and showed several bulging areas of parenchyma with an intact capsule. The central zone was occupied by a bulging mass of pale tan soft to rubbery tissue with vague nodularity.
Histologic examination revealed a similar infiltrate of cells with pale eosinophilic cytoplasm with large single vacuoles and slightly eccentric, enlarged nuclei with prominent single nucleoli. The neoplastic cells were arranged in sheets and singly within the stroma including extracapsular extension and extensive perineural invasion. The infiltrate involved bilateral anterior aspects of the prostate as well as the right posterior (apical and mid) portions. Bilateral seminal vesicles were uninvolved.
Immunohistochemical staining of the signet ring cells shows strong diffuse expression of PSA and weak patchy expression of CK20. The neoplastic cells did not stain with CK7 or CDX2. The large cytoplasmic vacuoles were mucicarmine negative.
One lymph node identified in the left pelvic dissection also showed a similar infiltrate of neoplastic cells.