Testis, Interstitial Cell - Hyperplasia
comment:Hyperplasia of interstitial cells (Leydig cells) can be focal, multifocal ( Figure 1 and Figure 2 ), or diffuse ( Figure 3 and Figure 4 ) and consists of an increased number of interstitial cells, which are noncompressive to the adjacent seminiferous tubules. Diffuse hyperplasia is generally a physiologic response to hormonal imbalance, whereas focal hyperplasia commonly forms part of the continuum leading to interstitial cell adenoma. Distinction between focal hyperplasia and interstitial cell adenoma is frequently based on size, with hyperplasia being defined as having a diameter equal to three or fewer seminiferous tubules. The condition may be associated with testicular atrophy. Proliferative lesions of the interstitial cell are common age-related lesions of the testis, being particularly frequent in the F344 rat but also present at lower incidences in the Wistar rat and Sprague-Dawley rat. Strain differences are also present in mice. Interstitial cell hyperplasia and adenoma can be readily induced in rats by any chemical that increases circulating levels of luteinizing hormone. This includes many different structural classes of chemicals and drugs. In mice, estrogenic compounds are the most common cause of interstitial cell proliferation.
recommendation:Interstitial cell hyperplasia should be diagnosed, graded, and discussed in the pathology narrative, if exacerbated by treatment. When present in both testes, the diagnosis should indicate the condition is bilateral, and severity should be based on the more severely affected testis.
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