Pathology

Abstract

Adenoid cystic/basal cell carcinoma (ACBCC) is a rare neoplasm in the prostate. Definitive treatment is warranted, as among 19 patients previously reported by us, 5 had extraprostatic extension and 4 were metastatic. The HER-2/neu (c-erbB-2) gene has been reportedly overexpressed in adenoid cystic carcinomas in other organs, but its status in prostatic ACBCC was uncertain. Immunohistochemical staining and in situ hybridisation were carried out in 13 patients with ACBCC (11 from transurethral resection, 2 prostatectomy). One patient had metastasis to the lung. Citrate buffer and steam heat were used for antigen retrieval. Ten acinar adenocarcinomas of varying grades were also immunostained as controls. Protein and mRNA expression were 2+ to 3+ (of 3+) in all patients with ACBCC, compared to a breast cancer control with strong reactivity, whereas protein expression was noted in only one acinar carcinoma and mRNA expression was absent in all acinar carcinomas. Benign acini expressed HER-2/neu only in the basal layer. The finding of strong, consistent HER-2/neu expression in ACBCC suggests that treatment with Herceptin (trastuzumab) may be effective in patients with this rare tumour. Editorial Comment This is a rare tumor composed of prostatic basal cells. Due to few cases reported, it was considered that the tumor had indolent biologic potential and some authors called the lesion "adenoid cystic-like tumor of the prostate gland" (1). In 2003, Iczkowski et al. (2) published the largest series calling attention to the potential aggressiveness of this tumor requiring ablative therapy. From a total of 19 patients, 5 showed extraprostatic extension on radical prostatectomy and 4 (21%) metastases: liver (2 patients), lung (2 patients), bowel (1 patient), and corpus cavernosum (1 patient). It is worth mention that the PSA was normal in most of the patients. Only 5 patients had elevated serum PSA of 4.5 to 9.2 ng/mL. This is an important finding with implication in the biochemical monitoring post-prostatectomy. Based on the fact that HER-2/neu (c-erb-2) gene has been reportedly overexpressed in adenoid cystic carcinomas in other organs, Iczkowski and Montironi studied the expression of this gene in prostate tissue of 13 patients previously reported. Based on the finding that adenoid cystic/basal cell carcinoma of the prostate strongly expresses HER-2/neu we hope that treatment with Herceptin (trastuzumab) may be effective in patients with this rare and aggressive tumor.