[Early histopathological aspects of benign prostatic hyperplasia: myxoid-inflammatory nodules]

Infiltration of benign prostatic hyperplasia (BPH), nodular prostatic hyperplasia (NPH) or prostatic adenoma by mononuclear cells, predominantly lymphocytes, is a common finding in surgical specimens. The biological significance of this infiltration, very similar to chronic inflammation, is unknown, but it is suspected as being related to the pathogenesis and progression of the BPH. The identity and number of the infiltrating cells is not well known. The objectives of the present study were: 1) to describe in more detail the histologic pattern of early lesions BPH, that is myxoid nodules. 2) to count and locate these myxoid nodules and to analyse the possible influence of age 3) and describe the patterns of mononuclear cell infiltration in BPH.

One hundred and seventy-three specimens of BPH tissue were reviewed. These samples were processed routinely for histological examination and immunohistochemical examination was performed in selected cases in order to further define the cellular composition of the described lesions. The immunohistochemical stains were performed automatically. Vimentin, specific smooth muscle actin an desmin were use to show the stromal cells and CD3, CD20 and CD68 monoclonal antibodies were used to quantify the populations of T-lymphocytes, B-lymphocytes and macrophages, respectively. The number of myxoid nodules identified in each patient was counted and the maximum and minimum diameter measured. These data have been compared in two groups of patients, those younger than 57 years and those over 80. Statistical analysis has been performed with SPSS 13.0. Student s t test was used for bivariate analysis and Pearson s r for correlation.

Interstitial infiltration involving T and B lymphocytes with less macrophages was a constant finding of the early nodules of BPH. The bivariate analysis with Student s t has shown a statistically significant difference between the mean number of myxoid nodules (p

Inflammatory cells and myxoid nodules are a constant finding in BPH surgical samples. The mean number of myxoid nodules is significantly lower in younger patients. Interstitial distribution is the most common pattern of mononuclear cell infiltration. B and T-cell lymphocytes are the most frequently found inflammatory cells in early myxoid nodules.