Microcystic Stromal Tumor of Testicle: First Case Report and Literature Review

Abstract

Microcystic stromal tumor (MCST) is a rare subtype of sex cord-stromal neoplasm. Tumors from all 31 previously reported cases were located in the ovary. Herein, we present a unique case of a right-side testicular tumor in a 33-year-old Chinese male. The tumor is composed of predominantly lobulated cellular nodules separated by hyalinized fibrous stroma and they expressed CD10, β-catenin (nuclear), and cyclin D1. Molecular analysis identified a point mutation (c.110C>G) in exon 3 of CTNNB1. The histopathological features, immunohistochemistry profiles, and molecular analysis of this tumor were consistent with MCST of the ovary. Therefore, a diagnosis of MCST of the right testicle was determined. To the best of our knowledge, this is the first case of MCST occurring in the testicles. The study may provide new insights to the tumor biology of MCST and a better understanding of this rare entity.

Primary testicular microcystic stromal tumor: two case reports with a broad morphological spectrum and frequency of predilection site

“…To date, all of reported MCST were in adult gonads, including 72 cases in ovary and 4 cases (including two cases reported in the literature and two in this article) in testis [5]. MCST overwhelming occurs in middle-aged women, characteristically unilateral and sporadically bilateral masses [9], [10].…”

“…The hotspot area of single nucleotide point mutation of CTNNB1 in reported ovarian MCST usually fall in the codons 32, 33, 34, 35, and 37 [2], occasionally, one case exhibited an exon 3 deletion mutation (c.88_99del12) and was considered to have a similar role to those of point mutation identi ed in MCST [11]. Four testicular MCSTs (including previous and present cases) exhibited point mutation at c.110C > G [5], c.98C > T [6], c.100G > C and c.97T > G of CTNNB1, and all 4 variants are classi ed as pathogenic or likely pathogenic in both COSMIC and ClinVar, also these particular mutations have been found in ovarian MCST [8]. Some patients with the chromosomal (5q21.22) germline mutation of APC gene which resulted in the development of colorectal polyps, colonic adenocarcinoma, endometrial or fallopian tube neoplasm [9] [18].…”

Microcystic stromal tumour of testis

“…To the best of our knowledge, to date, only one case of testicular MCST has been published 5. Here, we have presented a second case with the distinct morphological features and characteristic immunohistochemical profile of MCST, including expression of vimentin, CD10 and beta-catenin.…”

“…The first and until now only case report on MCST in the testicle appeared in 2018, by Zhu et al 5. They presented a 33-year-old Chinese man with a mass in his right testicle.…”