Fusocellular gonadal stromal tumour of the testis with epithelial and myoid differentiation

Abstract

We describe an unusual fusocellular gonadal stromal tumour with a benign behaviour in the left testis from a 16-year-old man. The neoplasm consisted of a non-encapsulated proliferation of irregularly arranged, fusiform cell bundles in fibrous connective tissue. The tumour cells contained a slightly infolded nucleus, some dilated rough endoplasmic reticulum cisternae, abundant filament bundles which connected to subplasmalemmal electron-dense bodies, pinocytotic vesicles and a discontinuous basal lamina. The intercellular spaces were narrow and the tumour cells were joined by desmosomes. These cells were immunoreactive for muscle actin, alpha-actinin and vimentin. Focal immunostaining for collagen type IV was observed around the cells. No immunoreactivity for keratins, desmin S-100 protein or XIIIa factor was found. The findings suggest that the tumour arose from the peritubular myoid cells.

Myoid gonadal stromal tumor: a distinct testicular tumor with peritubular myoid cell differentiation

“…We diagnose this tumor as a myoid gonadal stromal tumor in keeping with the initial 1991 report [7]. In our review of the medical literature, we found 6 similar cases [4][5][6][7][8][9]. These tumors appeared to represent a distinct entity by displaying a distinct pattern of PTMC-like differentiation as characterized by electron microscopy and/or immunohistochemistry.…”

“…This pattern closely mimicked the phenotype of PTMCs; thus, we believed that this was a myoid gonadal stromal tumor. As summarized in Table 2, an additional 6 similar tumors have been reported-that is, the reported tumors all displayed unequivocal myogenous features by various studies and were circumscribed, intratesticular masses that followed a benign clinical course [4][5][6][7][8]. Specifically, these tumors contained myofilaments by electron microscopy and/or had clear-cut immunoreactivity for 1 or more smooth muscle markers, including desmin, SMA, MSA, or SMM.…”

“…The inner 3 to 5 layers demonstrate some features associated with smooth muscle cells or myofibroblasts-that is, they contain numerous thin filaments with focal densities consistent with actin filaments, intermediate filaments consistent with vimentin and desmin, and subplasmalemmal pinocytotic vesicles [1,2]. Unusual for archetypal smooth muscle cells, these fusiform cells exhibit a discontinuous basal lamina, relatively abundant rough endoplasmic reticulum, and variable numbers of cytoplasmic lipid droplets [3][4][5][6]. Immunohistochemically, these myoid cells stain for smooth muscle actin (SMA), smooth muscle myosin (SMM), desmin, and vimentin [1] and are specifically referred to as peritubular myoid cells (PTMCs) by histologists and other investigators [1][2][3][4][5][6].…”

Testicular (gonadal stromal) fibroma: Case report

“…Pinieux et al noted the presence of a small number of sex cord elements in two cases of TF using CD99/MIC2 (Sertoli and Leydig cells) and anti-inhibin (Sertoli, and Leydig granulosa cells) (7). Nistal et al pointed out that the TF in their case was negative for keratin, S-100 protein and factor XIIIa, and therefor suggests that this tumor stems from peritubular myoid cells (10). The differential diagnosis includes: leiomyoma, neurofibroma, solitary fibrous tumor, and fibrosarcoma.…”

Testicular Fibroma of Gonadal Stromal Origin with Minor Sex Cord Elements, Presenting with Hydrocele

“…Intratesticular fibrous tumors are even more uncommon 1 . In previously published reports they were described under different names such as diffuse stromal form of gonadal stromal tumor, 2 thecoma like sertoli cell tumor, 3 testicular fibroma, 4 theca cell tumor, 5 myoid gonadal stromal tumor with epithelioid differentiation, 6 to name but a few. According to the recent WHO classification they are considered as sex cord/gonadal stromal tumors and classified under the tumors of thecoma/fibroma group 7 .…”