Leydig cell nodular hyperplasia (LCNH) is a lesion that is less characterized than the familiar Leydig cell tumors. The paracrine effects of these lesions on adjacent gonadal stroma have not been widely documented. We present two cases of precocious puberty in pre-pubertal boys found to have a single LCNH with adjacent focal maturation of the seminiferous tubules. Blood tests showed elevated serum testosterone and dehydroepiandrosterone (DHEAS). Ultrasound revealed unilateral testicular enlargement with irregular echogenicity. Radical orchiectomy was performed. Histologically Leydig cell nodular proliferation without destruction of surrounding tubules was seen. Mature seminiferous tubules undergoing spermatogenesis were noted adjacent to the lesion, while away from the lesion seminiferous tubules were as expected in pre-pubescent boys. These cases emphasize the potential presence of both paracrine and endocrine effects in Leydig cell nodular hyperplasia. However, instances of the endocrine effects of hyperplastic Leydig cell lesions are more widely reported than the paracrine effects.
Keywords: leydig cells; nodular hyperplasia; paracrine effects.