The Histogenetic Base of Renal Capsular-derived Tumors

Abstract

Capsulomas comprise a category of very rare benign tumors derived from the renal capsule, the most encountered being myxomas and leiomyomas. To get more information on the histogenetic origin of these tumors, a comprehensive ultrastructural investigation on the human renal capsule has been done on kidney biopsy samples performed for nephropathologic diagnosis. The human renal capsule ultrastructure is similar to that of the mammalian renal capsule. There are two cellular layers: an inner layer made up of particular (immature) smooth muscle cells, and a second outer layer consisting of fibroblasts, collagen fibers, extracellular matrix, and telocyte-like cells. Two cases of leiomyomas of microscopic dimensions, situated beneath the capsule have been described. Data from the literature presenting the ultrastructure and perirenal location of myxomas support the affiliation of these capsulomas with the resident renal capsular cells. Based on ultrastructural studies, the authors demonstrate the presence of telocyte-like cells in the outer layer of the human renal capsule and propose distinct histogeneses for leiomyomas and for capsular myxomas as derived from the inner and outer capsular layers, respectively.

Telocytes of the male urogenital system: Interrelationships, possible functions, and pathological implications

“…Associated pathologies/dysfunctions Kidneys Renal cortex (Qi et al, 2012), Interstitium and renal capsule (Zheng et al, 2012) Macrophages blood vessels (Zheng et al, 2012) Erythropoiesis stromal tissue (Imeri et al, 2019), Organization/maintenance (Zheng et al, 2012) Myxomas (Mandache & Penescu, 2015), Ischemia (Li et al, 2014), Renal fibrosis (Zheng et al, 2018) Renal Pelvis Interstitium (Gevaert et al, 2012) Nerve endings blood vessels (Gevaert et al, 2012) ER signaling pathway (Gevaert et al, 2012) Unclear Ureters Lamina Propria, Sheath of Waldeyer (Rusu et al, 2018b) Epithelial cells nerve endings blood vessels (Rusu et al, 2018b;Zheng et al, 2012) Stem/progenitor niche (Dobra et al, 2018), Stromal tissue organization/maintenance (Zheng et al, 2012) Hydronephrosis (Wolnicki et al, 2019)…”

“…Starting with those of the urinary tract, telocytes are found in the kidneys at the interstitium of the cortical region, in association with blood vessels and in the vicinity of renal tubules (Qi et al, 2012); these cells also establish numerous contacts with macrophages in the sub‐capsular space of the kidney (Zheng et al, 2012). In addition to the cortical region, telocytes have also been found in the outermost layer of the renal capsule and may be cells giving rise to connective tissue tumors, myxomas, which also affect the kidneys (Mandache & Penescu, 2015; Rusu et al, 2018a). As for the function of renal telocytes, there is evidence that they could play a specific role in renal physiology, participating in the release of erythropoietin, a factor capable of inducing erythropoiesis.…”