Aggressive angiomyxoma of the epididymis: A case report

Abstract

Background: Aggressive angiomyolipoma is an extremely rare benign mesenchymal tumor that was originally described as a locally recurrent mucinous spindle cell tumour. Aggressive angiomyolipoma originates from myofibroblasts, vascular smooth muscle cells, or fibroblasts, and displays various phenotypes of myofibroblasts and abnormal muscle arteries. Aggressive angiomyolipoma was first identified in 1983 and fewer than 50 male patients have been reported to date. It is an extremely rare mesenchymal tumour and often confused with other diseases. Patients with epididymal aggressive angiomyolipoma lack typical symptoms, most of which occur incidentally, although some patients may experience mild pain, discomfort, and swelling. Pain may be exacerbated by pressure from the mass.

Case summary: A 66-year-old male was admitted to the hospital on January 14, 2022 with chief complaint of swelling in the left scrotum for one year. There was no apparent cause for the swelling. The patient did not consult with any doctor or receive any treatment for the swelling. The enlarged scrotum increased in size gradually until it reached approximately the size of a goose egg, and was accompanied by discomfort and swelling of the left cavity of the scrotum. The patient had no history of any testicular trauma, infection, or urinary tract infection. The patient urinated freely, 1-2 times at night, without urgency, dysuria (painful urination), or haematuria. There was no significant family history of malignancy. The patient underwent excision of the enlarged tumour and the left epididymis under general anaesthesia on January 18, 2022. Twelve months of follow-up revealed no recurrence. The patient was satisfied with the treatment.

Conclusion: Aggressive angiomyolipoma is extremely rare clinically and often confused with other diseases. The pathogenesis of aggressive angiomyolipoma is unclear and the clinical presentation is mostly a painless enlarged mass. The diagnosis of aggressive angiomyolipoma requires a combination of medical history, preoperative imaging such as computed tomography and magnetic resonance imaging, cytological examination and preoperative and postoperative pathological biopsy. The preferred treatment is surgery, with the possibility of a new alternative treatment option after hormonal therapy. Aggressive angiomyolipoma should be considered in the differential diagnosis of parametrial tumors of the male genital area that present as clinically significant masses. The high recurrence rate of aggressive angiomyolipoma may be related to incomplete tumor resection, and patients with aggressive angiomyolipoma are advised to undergo annual postoperative follow-up and imaging for recurrence.

Keywords: Aggressive angiomyxoma; Case report; Epididymal malignancy; Male reproductive system neoplasms; Mesenchymal tumor; Orchiectomy; Scrotal mass.

Figure 1

Computed tomography and colour Doppler ultrasonography (testes, epididymis and spermatic cord). A: The computed tomography showed a cystic lesion in the left scrotum measuring about 6.6 cm × 5.5 cm with clear borders (orange arrow), and the left testicle was normal in size (white arrow); B: Ultrasound showed that the left testicle size was 4.3 cm × 2.8 cm × 2.6 cm (white arrow). On the left side of the scrotum there was a well-defined hypoechoic mass (orange arrow) with regular morphology and heterogeneous internal echogenicity.

Figure 2

Micropathological image of an epididymal mucocele in this case. A: Dilated, thick-walled, hyalinised blood vessels of variable size are seen microscopically (orange arrow); B: Clostridial and astrocytic tumour cells (orange arrow) were scattered in the mucus stroma with no evident heterogeneity. Original magnification of × 200.

Figure 3

Gross pathological picture of this case of epididymal mucinous neoplasm. A: The visible mass is an enveloped, white, grey, well-confined solid tumour (7.0 cm × 6.0 cm); B: A gel-like cut of the mass can be seen (orange arrow).