Leiomyomas, originating from smooth muscle cells, are common in the uterus but rare in the scrotum, presenting a clinical challenge. Scrotal leiomyomas, first described in the 19th century, are characterized by benign pathology from the subcutaneous dartos muscle. We present two cases of middle-aged males with scrotal leiomyomas, detailing clinical presentations, histopathological findings, and immunohistochemistry results. The first involved a 48-year-old with a painless scrotal lump, excised to reveal well-circumscribed smooth muscle bundles. Immunohistochemistry confirmed vimentin, desmin, and smooth muscle actin (SMA) positivity, consistent with scrotal leiomyoma. The second case featured a 25-year-old with a painless scrotal swelling, histologically matching the features of scrotal leiomyoma. Accurate diagnosis is crucial for guiding appropriate management strategies. Clinicians often employ a combination of clinical evaluation, imaging studies, and histopathological examination to confirm the presence of scrotal leiomyomas. Ultrasound remains a valuable tool for assessing the size, location, and vascularity of the tumor, aiding in the formulation of a differential diagnosis. Definitive diagnosis, however, relies on histological examination, which typically reveals spindle-shaped smooth muscle cells arranged in interlacing bundles.

Case 1

A 48-year-old male presented with a painless lump on the right side of the scrotum persisting for the past 9 months. Upon physical examination, a firm, non-tender, mobile, and round lump measuring 1.5 cm × 1.5 cm × 1 cm was identified at the root of the right scrotum, distinct from the testes. The overlying skin appeared normal, and no palpable inguinal lymph nodes were observed. Clinically, the lump was preliminarily diagnosed as a papilloma. Subsequently, it was excised and submitted for histopathological evaluation.
The gross examination revealed a single, partially skin-covered, grey-brown soft tissue piece measuring 1.5 cm × 1.5 cm × 0.8 cm. The cut surface exhibited a solid, and homogeneous tumor with whorling.
Microscopic examination unveiled a stratified squamous epithelial-lined tissue. In the subepithelium, a well-circumscribed tumor comprised interlacing bundles of smooth muscles with varying amounts of admixed collagen, displaying hyaline degeneration. Individual muscle cells exhibited uniform size and shape, with oval to spindle nuclei and bipolar cytoplasm. No cytological atypia or increased mitotic figures was observed. Immunohistochemistry indicated positive expression for vimentin, desmin and smooth muscle actin (SMA). Ki67 proliferation index was 2-3% (Figure 1).
The final diagnosis was confirmed as scrotal leiomyoma. The post-operative period was uneventful with no complications/ recurrence till date.

Case 2

A 25-year-old man presented with complaints of scrotal swelling persisting for the past year. Upon physical examination, a firm, non-tender, mobile, round lump measuring 2 cm × 1.5 cm × 1 cm was identified on the right side of the scrotum. The lump exhibited no palpable connection to the testes, epididymis, or spermatic cord. The overlying skin appeared normal without any ulceration, and both testes were normal, with no palpable inguinal lymph nodes. Clinically, the scrotal lump was diagnosed as an epidermal inclusion cyst. The swelling was excised and submitted for histopathological examination.
The gross examination of the scrotal swelling revealed a single, partially skin-covered, grey-brown soft tissue piece measuring 1.5 cm × 1.5 cm × 0.8 cm. The cut surface appeared solid, and homogeneous, and displayed a whorling pattern.
Microscopic examination of the scrotal swelling revealed stratified squamous epithelial-lined tissue. The subepithelium exhibited a well-circumscribed tumor composed of interlacing bundles of smooth muscles with varying amounts of admixed collagen. Individual muscle cells were uniform in size and shape, with oval to spindle nuclei and bipolar cytoplasm. No evidence of cytological atypia or mitotic figures was observed. Immunohistochemistry results indicated positivity for vimentin, desmin, and SMA (Figure 2). Ki67 proliferation index was 1-2%. The histopathological features were consistent with scrotal leiomyoma.
The post-operative period was uneventful with no complications/ recurrence till date.

Scrotal leiomyomas, infrequently encountered, typically manifest as asymptomatic lesions and are more commonly observed in middle-aged Caucasian men. Patients usually present with painless, small, solitary cutaneous lesions. The painless nature aligns with the tumor's slow growth, exerting pressure on nerves rather than compressing them [6-11]. While the exact etiology remains unclear, hormonal factors and genetic predispositions have been proposed as potential contributors. The rarity of scrotal leiomyomas often leads to misdiagnosis or delayed diagnosis, emphasizing the importance of raising awareness among healthcare professionals. In our cases, both patients presented with slow-growing, painless, small, solitary scrotal masses.
Scrotal smooth muscle tumors are classified into leiomyoma, atypical leiomyoma, and leiomyosarcoma. Four pathological criteria are utilized to grade scrotal smooth muscle cell tumors, including size ≥ 5cm in greatest dimension, infiltrative margin, ≥5 mitotic figures per 10 high power fields, and moderate cytological atypia. Tumors meeting only one criterion are deemed benign, those fulfilling two criteria are considered atypical leiomyoma, and those demonstrating three or four criteria are classified as leiomyosarcoma.
Previously, Adil et al. (2021) reported a case of scrotal leiomyoma in an 82-year-old male with a left scrotal mass persisting for 3 years. Imaging studies revealed a left paratesticular mass, and surgery confirmed the histopathological features consistent with scrotal leiomyoma [12]. Egharevba et al. (2020) also presented a case of scrotal leiomyoma in a 39-year-old male with a progressive right-sided hemiscrotal swelling over one year, which was excised, and histopathology revealed scrotal leiomyoma [13]. Table 1 summarizes the previously reported cases of scrotal leiomyoma.
Accurate diagnosis is crucial for guiding appropriate management strategies. Clinicians often employ a combination of clinical evaluation, imaging studies, and histopathological examination to confirm the presence of scrotal leiomyomas. Ultrasound remains a valuable tool for assessing the size, location, and vascularity of the tumor, aiding in the formulation of a differential diagnosis. Definitive diagnosis, however, relies on histological examination, which typically reveals spindle-shaped smooth muscle cells arranged in interlacing bundles.
Clinical manifestations of scrotal leiomyoma may lack distinctive characteristics, with a clinical differential diagnosis including sebaceous cysts, fibromas, adnexal tumors, neurofibromas, schwannomas (if painful), and squamous cell carcinoma (if ulcerated) [8, 14]. If there is any adhesion to the testis, consideration should be given to the possibility of atypical leiomyoma or leiomyosarcoma. Surgical excision stands as the primary treatment for scrotal leiomyomas. Complete excision is generally curative, with a low rate of recurrence reported in the literature. Minimally invasive techniques, such as laparoscopy or sclerotherapy, have shown promising results in select cases. However, the optimal approach may vary based on the size and location of the tumor, as well as the patient's overall health. Long-term follow-up is essential to monitor for recurrence and assess the overall prognosis [3].
Given the limited number of reported cases and the paucity of large-scale studies, scrotal leiomyomas remain an enigmatic entity in the realm of genitourinary tumors. Further research is warranted to elucidate the underlying molecular mechanisms, explore potential biomarkers for early detection, and refine treatment algorithms. Collaborative efforts among researchers and clinicians will be instrumental in creating a comprehensive understanding of scrotal leiomyomas and improving patient outcomes.

Scrotal leiomyomas, though rare, demand attention and careful consideration in the medical community. A deeper exploration of their clinical features, diagnostic tools, and treatment options is crucial to enhance our understanding of this unique tumor. As we continue to unravel the mysteries surrounding scrotal leiomyomas, collaborative research efforts will pave the way for improved diagnostic accuracy, optimal therapeutic interventions, and ultimately, better outcomes for affected individuals.

Acknowledgements

Not applicable.

Ethical policy

Informed patient consent was taken. Any identifying details (such as name, date of birth) of the patient will not be published.

Availability of data and materials

That data is available from the corresponding author on request.

Author contributions

All authors contributed to the study conception and design.Material preparation, data collection and analysis were performed by Pooja Verma, Sana Ahuja, Adil Aziz Khan and Sufian Zaheer. The first draft of the manuscript was written by Pooja Verma and Sana Ahuja and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Competing interests

The authors have no conflicts of interest to declare.

Funding

None.

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