Leiomyomas are benign tumours that originate from smooth muscles cells and are often found as benign lesions arising in the uterus [¹,²]. But there are also been seen cases of leiomyomas of the renal pelvis, bladder, spermatic cord, epididymis, prostate, scrotum and the glans penis [¹,^3-6]. Rare cases of a primary ovarian leiomyoma [⁷] , leiomyoma of the testis [⁸] or leiomyoma of the kidney have been also reported [⁹]. Leiomyomas of the tunica albuginea are extremely rare, and to our knowledge only five cases have been reported so far [^10-15]. In case of a bilateral leiomyoma so far only two cases are reported [¹⁴]. Here we present a case of a leiomyoma of the tunica albuginea.

Leiomyomas are benign tumours orginate from smooth muscles cells. Three different types respective to their origin are known; (1) derivation of arrector pili muscle (piloleiomyoma), (2) derevation of smooth muscles of blood vessels (angioleiomyoma), and (3) genital leiomyoma (p.e. from the smooth muscles of the scrotum) [¹⁶]. Tumours of mesenchymal origin in the scrotum are rare, more often cutaneous epithelial tumours are seen [¹³]. Patients with a leiomyoma of the tunica albuginea are usually about the sixth decades [^10-15]. Leiomyomas of the tunica albuginea considered to be of benign behaviour. It shows no invasive growth or metastasis [¹⁴]. In sonographic investigations potential differential diagnosis are inflammatory hydrocele, and multiloculated hematocele [¹⁷] and a Sertoli cell tumour of the testis [¹⁸]. Tumours arising from the testicular tunics are rare and in the most cases fibromas [¹²]. The potentially aetiology of leiomyomas of the tunica albuginea is discussed controversial. They could arise from the smooth muscle from blood vessels [¹²] but also may be from totipotent teratoma [¹⁰]. Possible differential diagnosis is an inflammatory myofibroblastic tumor (IMT) of the spermatic cord [¹⁹]. IMTs are also seen in the lung [²⁰] and are neoplasms of proliferating myofibroblasts, with a variable inflammatory component [¹⁹]. Immunohistochemically leiomyomas of the tunica albuginea are positive for Desmin as we could show in the present case report, IMTs are negative [¹⁹]. Thus, Desmin is useful to distinguish these two tumours. An orchiectomy is not necessary and instantaneous section should be performed while operation. In this case, the tumour is growing slowly and compressed surrounding structures, causing a hypoplastic testis. Interestingly in ultrasound a second lesion on the other testis from the same appearance could be seen. The patient disagreed excising this lesion because of absent pain in this area. Probably this case is also a bilateral leiomyoma. As the patient did not agree for surgery on the left side, we probably will report in a few years in case of tumour progress and consecutive pain, which was the reason for the patient for surgery on the right side.

This is an extremely rare and interesting case of a leiomyoma of the tunica albuginea. As far as we know only 5 cases of this tumour of the tunica albuginea have been reported. Leiomyomas in this area increasing slowly and may cause scrotal pain. Leiomyomas can be a possible differential diagnosis in this area.

The authors declare that they have no competing interests.

FB and FJK drafted the manuscript and were responsible for the interpretation of the data. FB and CLB were responsible for microscopic and histopathologic elements. LT, FK and EH cared for the patients. EH was responsible for the critical revision of the manuscript. All authors read and approved the final manuscript.

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