Myoid Gonadal Stromal Tumor

A Clinicopathologic Study of Three Cases of a Distinctive Testicular Tumor

Chia-Sui Kao, MD; Thomas M. Ulbright, MD

Disclosures

Am J Clin Pathol. 2014;142(5):675-682. 

In This Article

Results

Clinical Features

The patients were aged 38, 43, and 59 years, and each had a single testicular mass. All tumors were unilateral with one left-sided and two right-sided. Serum tumor markers (α-fetoprotein and β–human chorionic gonadotropin) obtained prior to surgery in one patient were within normal limits. No patient was known to have hormonal abnormalities or clinical syndromes occasionally associated with some types of sex cord–stromal tumors.[16–23]

Pathologic Features

A summary of pathologic features is provided in Table 2. On gross examination, all were unifocal and well circumscribed with a yellow/tan appearance. The sizes were 1.2, 1.3, and 3.2 cm in the greatest dimension. On low-power examination, all were circumscribed and nonencapsulated, focally contained medium- to large-sized ectatic blood vessels and were adjacent to the rete testis Image 1A. The tumor cells were spindled and mostly arranged in short intersecting fascicles (n = 2) Image 1B with varying degrees of thin collagen bands in the background Image 1C; one case contained short, broad tumor fascicles. The nuclei ranged from elongated to fusiform with inconspicuous to small nucleoli and occasional grooves Image 1D. The cytoplasm was scant (n = 2) to moderate (n = 1) and ill-defined, ranging from pale to lightly eosinophilic; none had perinuclear vacuoles (Image 1D). No significant cytologic atypia was present. The number of mitotic figures varied from zero to five per 10 high-power fields. All lacked tumor necrosis and lymphovascular invasion. Two had entrapped seminiferous tubules at the periphery Image 1E. The seminiferous tubules adjacent to the tumor showed normal spermatogenesis. A sex cord component was absent in all cases, verified by pericellular reticulin staining in one case.

Image 1.

A, Low-power view shows a well-circumscribed, nonencapsulated myoid gonadal stromal tumor adjacent to the rete testis (left) and focally containing ectatic blood vessels and scattered thin collagen bands (H&E, ×40). B, The spindled tumor cells are arranged in short intersecting fascicles (H&E, ×150). C, There are patchy collagen deposits in the background (H&E, ×150). D, Nuclear grooves are occasionally present (center). Note the mitotic figure at the right and occasional small nucleoli (H&E, ×400). E, Entrapped seminiferous tubules are at the periphery of the tumor (H&E, ×150). F, An unclassified, spindle cell–predominant sex cord–stromal tumor with small, tight clusters of sex cord cells with dark nuclei and scant cytoplasm (top right) (H&E, ×200). Inset: reticulin stain shows the nested arrangement of sex cord cells lacking reticulin fibers (×300).

The tumor was positive for the following immunohistochemical stains: S100 protein (three of three) Image 2A, SMA (three of three) Image 2B, FOXL2 (three of three) Image 2C, SF-1 (three of three), vimentin (three of three), inhibin (focal, three of three), desmin (two of three), calponin (focal and weak, two of two), and WT1 (one of three). Staining for h-caldesmon Image 2D, calretinin, SOX9, and CD34 (two cases) was consistently negative. Synaptophysin, chromogranin, and cytokeratin AE1/3 were negative in one case. The peritubular myoid cells in the adjacent seminiferous tubules were positive for SMA, desmin, h-caldesmon (Image 2D), and calponin but negative for S100 protein (Image 2A), inhibin, calretinin, WT1, SOX9, FOXL2, and SF-1.

Image 2.

Myoid gonadal stromal tumor showing diffuse, strong positivity for S100 (A, ×150), smooth muscle actin (B, ×150), and FOXL2 (C, ×150). The tumor is negative for h-caldesmon (D, ×150), whereas the peritubular myoid cells are positive

Treatment and Clinical Follow-up

Clinical follow-up showed all three patients were alive with no evidence of recurrent or metastatic disease at 5, 31, and 58 months postorchiectomy. Two patients had followup computed tomography scans of the abdomen and pelvis, which showed no retroperitoneal disease; one of these patients (whose tumor was 1.2 cm) underwent "virgin" retroperitoneal lymph node dissection 1 month after orchiectomy, which confirmed the absence of metastatic disease. None received any other form of adjuvant therapy. A summary of testicular myoid gonadal stromal tumors, including those previously reported in the literature, is provided in Table 3.[1–5]

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