Abstract:

Objective

Retroperitoneal extrarenal or pelvic epithelioid angiomyolipomas are clinically rare, and some of them show malignant biological behavior.Due to the lack of specific symptoms and imaging findings, patients often experience a delayed diagnosis and treatment.This study aimed to improve the understanding of this disease by summarizing our diagnosis and treatment experience with 14 cases and reviewing the literature.

Methods

The clinical data of 14 patients with retroperitoneal extrarenal or pelvic epithelioid angiomyolipoma who underwent surgical treatment and achieved pathological confirmation in Peking University International Hospital from January 2014 to April 2024 were retrospectively analyzed.The clinical manifestations, imaging and pathological features, diagnosis, and treatment of the disease were summarized based on the domestic and foreign literature.

Results

There were 4 males and 10 females in this group.The patients ranged in age from 20 to 67 years at presentation, with a median age of 39 years.There were 12 cases of initial onset (4 cases discovered in physical examination, 5 cases of abdominal discomfort, 2 cases of low back pain, 1 case of constipation) and 2 cases of recurrence.The lesions were located in retroperitoneal region in 11 cases and pelvic cavity in 3 cases.Plain CT scans showed slightly lower or equal density, and the tumor could have internal bleeding and necrosis when it was large.The solid component showed uneven and obvious enhancement.All patients in this group underwent open surgery.Postoperative pathology indicated malignancy in 10 cases.Immunohistochemical staining was positive for HMB45 in 85.7% (12/14) of patients, for MelanA in 64.3% (9/14), and for SMA in 91.7%(11/12).Postoperative complications in 2 cases (abdominal hemorrhage in 1 case and wound infection in 1 case) improved after conservative treatment.The patients underwent regular follow-up after discharge.As of July 2024, the follow-up time ranged from 4～88 months, with a median time of 35 months.Two cases were lost to follow-up.One case (case 13) was confirmed to have pelvic tumor recurrence 5 months after surgery(being on oral sirolimus treatment now).One case (case 5) had no significant changes in residual tumor in abdominal aortic wall, and no tumor recurrence or metastasis was observed in the remaining patients.

Conclusion

Extraperitoneal extrarenal or pelvic epithelioid angiomyolipomas are most common in young and middle-aged women.The clinical manifestations of the disease are atypical.The low diagnostic accuracy of imaging examination easily leads to confusion with liposarcoma and vasogenic tumor.Diagnosis of the disease depends on postoperative pathology and immunohistochemistry.The specific simultaneous expression of melanin markers (HMB45 and Melan-A) and myogenic markers (SMA) is characteristic.Surgical resection is the preferred treatment option, but mTOR inhibitors are promising for the treatment of the disease.Some patients present with malignant neoplastic features.Tumor recurrence and distant metastasis can still occur in these patients even after surgical treatment, so regular follow-up observation is required after surgery.

Key words: Epithelioid angiomyolipomas, Diagnosis, Treatment