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Myoid gonadal stromal tumor, a case report with review of the literature D’Abbronzo G, Ronchi A, Belfiore MP, Mantia EL, Feroce F, Pignata S, Perdonà S, Franco R


The diagnosis of myoid gonadal stromal tumor (MSGT) can represent a difficult challenge, both for the extreme rarity of this neoplasm and for the clinical-radiological characteristics similar to other neoplasms of the testicle. The case management we present suggests how a complete differential diagnosis can be obtained by integrating ultrasonographic and pathological data.

Keywords: Histological description, myoid gonadal stromal tumor, ultrasound description

How to cite this article:
D’Abbronzo G, Ronchi A, Belfiore MP, Mantia EL, Feroce F, Pignata S, Perdonà S, Franco R. Myoid gonadal stromal tumor, a case report with review of the literature. Indian J Pathol Microbiol 2022;65:444-7

How to cite this URL:
D’Abbronzo G, Ronchi A, Belfiore MP, Mantia EL, Feroce F, Pignata S, Perdonà S, Franco R. Myoid gonadal stromal tumor, a case report with review of the literature. Indian J Pathol Microbiol [serial online] 2022 [cited 2022 May 4];65:444-7. Available from: https://www.ijpmonline.org/text.asp?2022/65/2/444/343206

   Introduction   Top

Myoid gonadal stromal tumor (MGST) is “an emerging entity composed of spindle-shaped cells showing features of smooth muscle and gonadal stroma”.[1] MGST is a very rare entity, included in the group of stromal tumors, and the differential diagnosis with other gonadal stromal neoplasms is mandatory, because of different clinical and prognostic features.

Herein, we report a case of such a testicular tumor, with documented preoperative ultrasound (US) description. To our knowledge, only eight cases of this rare distinctive neoplasm have been reported so far, but none of them included a detailed US description.[2],[3],[4],[5],[6]

   Case Presentation   Top

A 41-year-old man was admitted due to infertility. The patient presented an unremarkable medical history, and laboratory data showed no abnormalities. On physical examination, the testicular volume was normal, whereas on left scrotal palpation, a well-circumscribed, painless nodule was found. Ultrasound was performed with different scan plans: longitudinally for the visualization of the epididymal head and transversally for the evaluation of testicular parenchyma. The echo-structure of the patient’s left testis appeared uneven due to the presence of a 10-mm oval formation with a lower polar seat. The nodule appeared inhomogeneous, as it was mainly hypoechoic with contextual hyperechoic echoes. At Doppler examination, the vascularization pattern was located predominantly at the periphery of the nodule, with only rare central vascular spots [Figure 1].

Figure 1: Ultrasound features of the testicular mass found on physical examination

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Intraoperative biopsy of the nodule showed a stromal tumor that was unencapsulated but contained a well-circumscribed proliferation of spindle cells, arranged into fascicles within a collagenous stroma. Moreover, neoplastic cells showed eosinophilic cytoplasm and nuclear pleomorphism with spindle and round nuclei without significant atypia. The surrounding testicular parenchyma appeared atrophic, but uninvolved by the neoplasm [Figure 2]a, [Figure 2]b, [Figure 2]c. Mitotic figures and necrosis were absent. Immunohistochemistry showed positivity for SMA, S-100, and SF1 [Figure 2]d, [Figure 2]e, [Figure 2]f, and negativity for other markers such as desmin, caldesmon, and calponin melanA, mart1, HMB45, inhibin, SOX9, calretinin. Morphological features and the positivity to S-100 and SMA led us to make a diagnosis of myoid gonadal stromal tumor. At present, the patient has no disease progression after a 3 years follow-up.

Figure 2: Histological findings. (a) The neoplasm was relatively well circumscribed but not encapsulated. Residual testicular parenchyma was present (upper half) (H and E, original magnification 100 ×). (b) The neoplasm was organized in short fascicles with intervening collagen bundles (H and E, original magnification 100 ×). (c) The neoplastic cells were spindle-shaped with lightly eosinophilic cytoplasm (H and E, original magnification 400 ×). The neoplastic cells resulted positive for actin (d, original magnification 200 ×), S100 (e, original magnification 400 ×), and SF1 (f, original magnification 400 ×)

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   Discussion   Top

Myoid Gonadal stromal Tumor is a rare neoplasm of the gonads constituted by spindle cells showing features of the smooth muscle and gonadal stroma. The term “ Myoid Gonadal stromal Tumor “ was first used by Weidner in 1991 to define a neoplasm found which was “composed of spindle cells forming interweaving fascicles associated with focally prominent bands of broad collagen bundles.”[2],[3]

Immunohistochemical and ultrastructural features of these neoplasms allow hypothesizing their origin from peritubular myoid cells despite the negativity of desmin.[4],[5] In fact, loss of desmin is a feature of peritubular cells in most testicular disorders involving germ cell depletion.[7]

Diagnosis of MGST may be challenging, but it can be obtained by integrating its US features with the histological ones. [Table 1] reports the main ultrasonographics, histological, and immunohistochemical characteristics of the previously documented cases of MGSTs compared to our case.

Table 1: Previous documented case of Myoid Gonadal Stromal Tumors with main features of our case

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Although US findings are not specified in the case of MGST, they may be helpful in differentiating it with other more frequent neoplasms. In our case, seminoma was excluded in view of the normal dimension of the epididymis and the absence of microlithiasis that is present in one-third of the cases.[8] Another neoplasm that should be excluded in the differential diagnosis of MSGT is embryonic carcinoma which appears as a hypoechoic mass with a more inhomogeneous echostructure than our case due to the presence of areas of cystic change, hemorrhages, and calcification. In addition, embryonic carcinoma presents a rapid growth, and when it is in an eccentric position, it causes infiltration and distortion of the albuginea profile. These elements are not present in our case. The US examination allowed us to exclude forms of mixed neoplasia, which are more heterogeneous.[8],[9] Finally, MGS presents US findings similar to sex cord–stromal tumors (Sertoli cells tumor and Leydig cells tumor). However, sertoli cell tumors often present as a single hypoechoic nodule, but it is not uncommon to find multiple hypoechoic foci with hyperechoic areas if calcified areas are present, whereas Leydig cells’ tumor looks like a single, nonpalpable, hypoechoic lesion with increased vascularization than our case.[9]

The histological differential diagnosis primarily includes leiomyoma, testicular fibrothecoma, adult granulosa cell tumor, and unclassified sex cord–stromal tumor.

Leyomioma, differently our case, shows fascicular growth of spindle smooth muscle cells with abundant eosinophilic cytoplasm and box-scar nuclei accompanied by perinuclear halos. Furthermore, the immunohistochemical profile of leiomyoma (negativity for S100 and positivity for desmin and caldesmon) is opposite to immunohistochemical profile of MGST (positivity for S100, negativity for desmin and caldesmon).[5]

Testicular fibrothecoma is typically characterized by thicker collagen bundles, forming hyaline plaques similar to those seen in the ovarian counterpart. Moreover, testicular fibrothecoma exhibits atypia and a minimal invasion in the surrounding testis. In addition, testicular fibrothecoma shows frequent diffuse positivity for inhibin and calretinin with variable S100 protein reactivity.[10]

Adult granulosa cell tumor can be morphologically similar to MGST; however, if stroma is present in adult granulosa cell tumor, it may be fibrocollagenous or edematous. We did not detect these peculiars in our case. The immunohistochemical profile can be helpful for differential diagnosis. Indeed, adult granulosa cell tumors are typically positive for vimentin, inhibin, calretinin, and CD99. In our case, the neoplasm showed negativity for inhibin and calretinin.[1]

Finally, the absence of intermingled sex cord cells (sertoli or l leydig cells), along with morphological and immunohistologic features allowed us to rule out unclassified sex cord–stromal tumor.[1]

Except for Nistal et al.,[4] the authors of previously documented cases conducted a follow-up of the patients and reported the absence of evidence of disease and the survival of patients over 12 months as in our case. This data would seem to confirm the benign behavior of these neoplasms indicated by “WHO Classification of Tumors of the Urinary System and Male Genital Organs”.[1]

Although the diagnosis of MGST may represent a difficult challenge for pathologists, we suggest that the integration of the data obtained from the US examination (presented here for the first time) with the characteristic morphological and immunohistochemical profile of the tumor provide a complete differential diagnosis, allowing to reasonably exclude neoplasms with worse prognosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.


   References   Top

Olivia M, Young RH, Alnright M. Sex cord stromal-tumours. In: Moch H, Cubilla AL, Humphrey PA, Reuter VE, Ulbright TM, editors. The 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs. 4th ed. Lyon: WHO Press; 2016. p. 235.  Back to cited text no. 1
Greco MA, Feiner HD, Theil KS, Mufarrij AA. Testicular stromal tumor with myofilaments: Ultrastructural comparison with normal gonadal stroma. Hum Pathol 1984;15:238-43.  Back to cited text no. 2
Weidner N. Myoid gonadal stromal tumor with epithelial differentiation (?? testicular myoepithelioma). Ultrastruct Pathol 1991;15:409-16.  Back to cited text no. 3
Nistal M, Puras A, Perna C, Guarch R, Paniagua R. Fusocellular gonadal stromal tumour of the testis with epithelial and myoid differentiation. Histopathology 1996;29:259-64.  Back to cited text no. 4
Du S, Powell J, Hii A, Weidner N. Myoid gonadal stromal tumor: A distinct testicular tumor with peritubular myoid cell differentiation. Hum Pathol 2012;43:144-9.  Back to cited text no. 5
Kao CS, Ulbright TM. Myoid Gonadal Stromal Tumor: A clinicopathologic study of three cases of a distinctive testicular tumor. Am J Clin Pathol 2014;142:675-82.  Back to cited text no. 6
Santamaría L, Martín R, Nistal M, Paniagua R. The peritubular myoid cells in the testes from men with varicocele: An ultrastructural, immunohistochemical and quantitative study. Histopathology 1992;21; 423-33.  Back to cited text no. 7
Geraghty MJ, Lee FT, Bernsten SA, Gilchrist K, Pozniak MA, Yandow DJ. Sonography of testicular tumors and tumor-like conditions: A radiologic- pathologic correlation. Crit Rev Diagn Imag 1998;39:1-63.  Back to cited text no. 8
Isidori AM, Pozza C, Gianfrilli D, Giannetta E, Lemma A, Pofi R, et al. Differential diagnosis of non palpable testicular lesions: Qualitative and quantitative contrast-enhanced US of benign and malignant testicular tumors. Radiology 2014;27:606-18.  Back to cited text no. 9
Zhang M, Kao CS, Ulbright TM, Epstein JI. Testicular fibrothecoma: A morphologic and immunohistochemical study of 16 cases. Am J Surg Pathol 2013;37:1208-14.  Back to cited text no. 10


Correspondence Address:
Renato Franco
Pathology Unit, Department of Mental and Physical Health and Preventive Medicine, University of Campania “Luigi Vanvitelli”, Naples, Via Luciano Armanni, 5 80138 Napoli
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.343206

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[Figure 1], [Figure 2]
[Table 1]



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