Since 1983, when aggressive angiomyxoma was first described by Steeper and Rosai, there were about 100 cases reported worldwide (including 24 males). It often occurs in middle-aged patients ranging in age between 13 and 78 years (mean age 46). In men, AAM is usually derived from the pelviperineal interstitial tissue involving the scrotum (38%), spermatic cord (33%), perineal region (13%) and intrapelvic organs such as the bladder (8%) [1
AAM in the scrotal region may present as a scrotal mass, wrongly diagnosed as hernia or hydrocele, as has been previously reported in few cases [3
]. It is uaually difficult to identify the tumor by imaging studies such as ultrasonography and there are reports showing some advantage to scrotal MRI as it better demonstrates the angiomatous and myxomatous nature of the tumor. However, most cases are currently visualized by CT scans which are more accessible for the patients. US-guided needle biopsy has been shown to give inconclusive diagnosis [5
] and the differential diagnosis includes angiomyofibroblastoma, myxoma and myxoid liposarcoma. Therefore, the final diagnosis usually awaits the final histological examination of the excisional specimen. Macroscopically, its typical appearance is of a large, grossly gelatinous and locally infiltrative tumor. The microscopic appearance of the stroma is rich of collagen, fibriles, and a prominent vascular component including many thick-walled vessels. The anomalous muscular artery is very specific for diagnosis of AAM and is the major histological difference from angiomyofibroblastoma. Immunohistochemical studies may reveal that tumor cells are immunoreactive for desmin, muscle specific actin and vimentin. Estrogen and progesteron receptor protein may be positive. The tumor cells are immunonegative for S100 protein, factor VIII related antigen, carcinoembryonic antigen and cytokeratin. Therefore, in order to differentiate the AAM from myxoma and myxoid liposarcoma the tumor cells must be positive for Vimentin and negative for S-100 protein [3
], as shown in the current presented case. Cytogenic analysis reveals chromosomal translocation involving chromosomes 8 and 12, associated with rearrangement of the HMGIC gene.
Surgery is the principal treatment to date and because of high risk of local recurrence (36–72%) a long-term postoperative followup with either US or CT is recommended [6
]. The frequent recurrence may be attributed to incomplete tumor resection and the earliest recurrence has been reported as appearing 9 months after surgery while the latest, 14 years thereafter [8
]. However, no distant metastasis has been reported to date [8
]. Alternatively, Poirier et al. have shown good response of the tumor to gonadotropin-relesing hormone agonist treatment which remarkably reduced the size of the tumor [6
In summary, AAM is a very rare benign neoplasm which is more predominant in females. In males, scrotal AAM may be misdiagnosed as hernia or a hydrocele mainly because of the lack of awareness of this entity.