Search

The incidence of ectopic Leydig cells (LCs) has been reported to be 40% to 90%. Several theories have been proposed to account for ectopic LCs, including in situ differentiation, migration from testicular interstitium, and trapping of peritubular LCs in the tunica propria of the seminiferous tubule during its thickening. To document the nature of ectopic LCs and to compare them with interstitial LCs, Sertoli cells, epididymal cells, mesothelial cells, and epithelial cells in rete testis, immunostainings with calretinin, CD10, inhibin, CK7, and CK20 were performed in 40 cases of orchiectomy specimens using tissue microarray sections. In addition, the frequency of ectopic LCs was evaluated. Of the 40 orchiectomy specimens, 14 cases demonstrated ectopic LCs with an incidence of 35%. Inhibin was positive in more than half of ectopic LCs (9/14, 64.3%) and in almost all interstitial LCs. Calretinin was positive in most of ectopic LCs (12/14, 85.7%) as well as in most of normally located interstitial LCs and mesothelial cells and some of rete testis epithelial cells. The ectopic and interstitial LCs as well as Sertoli cells were negative for CK7, CK20, and CD10. CK7 was positive in all epididymal cells and in most mesothelial cells and epithelial cells in rete testis. CD10 was positive in some of epididymal cells and epithelial cells in rete testis. CK20 was negative in all cells in the testis and epididymis. Ectopic LCs showed similar staining patterns to interstitial LCs with positive immunoreactivity for calretinin and inhibin. In this study, the frequency of ectopic LCs was 35%. The lower incidence in this study was most likely because of the limited sampling. Immunohistochemically, ectopic LCs showed identical immunohistochemical patterns with those of interstitial LCs. Calretinin appeared to be more sensitive but less specific than inhibin for LCs. Because calretinin is frequently positive in cells other than ectopic or interstitial LCs, a precaution is required to differentiate LCs from mesothelial cells and rete testis epithelial cells. Based on our study, we could not add anything else of what is known in regard to the histogenesis of ectopic LCs. The current theories including in situ differentiation, migration from testicular interstitium, and trapping of peritubular LCs in the tunica propria of the seminiferous tubules during its thickening seem to be valid histogenetic theories.

The incidence of ectopic Leydig cells (LCs) has been reported to be 40% to 90%. Several theories have been proposed to account for ectopic LCs, including in situ differentiation, migration from testicular interstitium, and trapping of peritubular LCs in the tunica propria of the seminiferous tubule during its thickening. To document the nature of ectopic LCs and to compare them with interstitial LCs, Sertoli cells, epididymal cells, mesothelial cells, and epithelial cells in rete testis, immunostainings with calretinin, CD10, inhibin, CK7, and CK20 were performed in 40 cases of orchiectomy specimens using tissue microarray sections. In addition, the frequency of ectopic LCs was evaluated. Of the 40 orchiectomy specimens, 14 cases demonstrated ectopic LCs with an incidence of 35%. Inhibin was positive in more than half of ectopic LCs (9/14, 64.3%) and in almost all interstitial LCs. Calretinin was positive in most of ectopic LCs (12/14, 85.7%) as well as in most of normally located interstitial LCs and mesothelial cells and some of rete testis epithelial cells. The ectopic and interstitial LCs as well as Sertoli cells were negative for CK7, CK20, and CD10. CK7 was positive in all epididymal cells and in most mesothelial cells and epithelial cells in rete testis. CD10 was positive in some of epididymal cells and epithelial cells in rete testis. CK20 was negative in all cells in the testis and epididymis. Ectopic LCs showed similar staining patterns to interstitial LCs with positive immunoreactivity for calretinin and inhibin. In this study, the frequency of ectopic LCs was 35%. The lower incidence in this study was most likely because of the limited sampling. Immunohistochemically, ectopic LCs showed identical immunohistochemical patterns with those of interstitial LCs. Calretinin appeared to be more sensitive but less specific than inhibin for LCs. Because calretinin is frequently positive in cells other than ectopic or interstitial LCs, a precaution is required to differentiate LCs from mesothelial cells and rete testis epithelial cells. Based on our study, we could not add anything else of what is known in regard to the histogenesis of ectopic LCs. The current theories including in situ differentiation, migration from testicular interstitium, and trapping of peritubular LCs in the tunica propria of the seminiferous tubules during its thickening seem to be valid histogenetic theories.

We report the case of a patient with three synchronous but histologically different primary renal tumors that were all in the same kidney. Two tumors were different subtypes of renal cell carcinoma (RCC), and the third was a variant form of angiomyolipoma. The patient was a 62-year-old man who was receiving antihypertensive drugs and came to our hospital for a regular check-up. Ultrasonography performed during the visit revealed a left renal mass, but the patient had no related symptoms. Subsequent computed tomography revealed two round, high-density masses, one in the mid-portion and the other in the lower pole of the left kidney, and multiple cysts in the right kidney and the liver. The mass in the mid-portion measured 3.3 × 3.0 × 2.8 cm, and the mass in the lower pole measured 1.7 × 1.1 × 0.9 cm. A left radical nephrectomy was performed. On gross examination, an additional ovoid nodule (0.6 cm in the greatest dimension) was found in the lower pole. Microscopically, the largest tumor consisted of a broad alveolar arrangement of large round cells with abundant eosinophilic or clear cytoplasm, distinct cell borders, and perinuclear halos, features consistent with chromophobe RCC. The smallest tumor was a conventional (clear-cell) RCC. The third tumor was composed solely of atypical epithelioid cells with prominent nucleoli and yellowish-brown to black pigments. The tumor cells were positive for melanin (Fontana-Masson stain), the melanoma marker HMB45, vimentin, smooth-muscle actin, and the macrophage marker CD68 and were negative for cytokeratin. This tumor was considered a pigmented epithelioid type of angiomyolipoma. The histologic, histochemical, and immunohistochemical features in this case confirmed the presence of three synchronous primary tumors, a chromophobe and a clear-cell type RCC and a pigmented epithelioid angiomyolipoma, all of which were in the same kidney. This case is the first of its type reported in the literature.