Diagnosis of Cowper's Glands on Prostate Needle Biopsy

Abstract

The presence of normal anatomic structures may be a source of confusion to the pathologist examining prostatic needle biopsies. The morphologic features of Cowper's (bulbourethral) glands incidentally biopsied during transrectal sampling of the prostate have not been described. We reviewed seven cases of Cowper's glands found in prostatic core biopsy specimens. Sections containing Cowper's glands were stained with hematoxylin-eosin, mucicarmine, periodic acid-Schiff's-digest (PAS-D), and antibodies directed at high-molecular-weight cytokeratin (HMWCK), prostate-specific acid phosphatase (PSAP), prostate-specific antigen (PSA), Ulex europaeus agglutinin, and muscle-specific actin. Histologically, Cowper's glands resemble mucinous minor salivary glands entrapped within fascicles of muscle. Lobules of acini composed of cells distended with mucin (mucicarmine and PAS-D positive) were admixed with ducts and ductules composed of hybrid cells with both mucinous and ductular epithelial features. The HMWCK was strongly reactive with the ductular epithelium and demonstrated an attenuated cell lining at the periphery of lobules. The mucinous cytoplasm reacted with U. europaeus, whereas the ductal elements failed to stain. PSAP stains were negative, with PSA positive in most cases. Muscle-specific actin was positive in three cases. Cowper's glands occasionally may be sampled by transrectal needle biopsy. Recognition of this anatomic structure will allow discrimination from low-grade prostatic adenocarcinoma, foamy gland carcinoma, mucinous metaplasia of prostate glands, and atypical glands of undetermined significance.

High-grade prostatic intraepithelial neoplasia

“…Furthermore, basal cells of Cowper's glands may not express keratin 34b-E12, 86 although this has been disputed. 87 Rare (0.2%) cases of adenocarcinoma have been reported that express keratin 34b-E12, including foci of metastatic high-grade adenocarcinoma; these cases did not appear phenotypically to be basal cell/ adenoid cystic carcinoma. 88 Basal cell hyperplasia is a histologic mimic of cancer, and use of antikeratin 34b-E12 is recommended in any equivocal cases that include this lesion in the differential considerations.…”

Benign mimickers of prostatic adenocarcinoma

“…20,21 They are rarely sampled in prostatic specimens. Cowper's glands have a lobular configuration with a central duct surrounded by tightly packed round acini composed of cells with abundant mucinous cytoplasm ( Figure 3).…”

“…Sometimes, skeletal muscle, typical of the apical region, is present in the periglandular stroma. Cowper's glands are rarely confused with small 20,21 The ductal cells exhibit high molecular weight keratin (34bE12) staining and in some cases attenuated cells around the periphery of the acini are also positive. 20 The latter cells may also exhibit smooth muscle actin positivity.…”

“…Cowper's glands are rarely confused with small 20,21 The ductal cells exhibit high molecular weight keratin (34bE12) staining and in some cases attenuated cells around the periphery of the acini are also positive. 20 The latter cells may also exhibit smooth muscle actin positivity. 20,21 Another differential diagnosis of Cowper's glands is mucinous metaplasia of prostatic acini which is usually seen in association with atrophy.…”

“…20 The latter cells may also exhibit smooth muscle actin positivity. 20,21 Another differential diagnosis of Cowper's glands is mucinous metaplasia of prostatic acini which is usually seen in association with atrophy. 22 Atrophy Atrophy of prostatic glands is a common process typically but not exclusively found in older patients.…”