RAML is a subset of perivascular epithelioid cell tumors with epithelioid tumor differentiation 3
. RAML can be seen together with TS or pulmonary lymphangioleiomyomatosis (LAM) and can also occur sporadically without both. 80% of RAMLs are sporadic and there is no relationship with any genetic syndromes. However, it is thought that TS is found in about 10% of RAML diagnosis 4
Sporadic RAML is most commonly seen in middle-aged women. The most serious complications are retroperitoneal hemorrhage (Wunderlich syndrome), hematuria and renal function disorder. Wunderlich syndrome can occur classically during pregnancy and hemorrhagic shock can be observed in 20% of patients 4. Sporadic RAML does not usually have symptoms and detected incidentally during renal imaging as a single lesion.
Unlike the sporadic RAML, multiple lesions in both kidneys are seen in RAML associated with the TS 5. Slow-growing sporadic RAML usually does not lead to deterioration of renal function 6. In the differentiation of patients with TS characteristic skin lesions in patients with RAML and the presence of other symptoms of TS should be considered such as benign tumors in multiple organs. Only 10% of RAML patients are associated with TS, but all patients should be evaluated for subclinical or undiagnosed TS. Sporadic RAML, compared with RAML associated with TS usually occurs in older age, being single, rarely causes symptoms and hemorrhages and grows more slowly 6. Active intervention is required more often in TS associated RAML patients compared to sporadic RAML patients.
Surgical treatment is suggested for patients with high suspicion of malignancy with intramural necrosis and / or calcification 7. Available interventions include nephron-sparing surgery (NSS), selective renal artery embolization, total nephrectomy and radiofrequency ablation. Intervention may vary according to the patient. NSS is an important option rather than total nephrectomy in 7-10 cm sized tumors and patients with multiple RAMLs 8. Selective renal artery embolization or total nephrectomy may be a viable option for tumors unsuitable for NSS due to tumor location, size, hemorrhage or urinary fistula risk. Self-limiting postembolization syndrome developed in 35.9% of patients in a study with 524 patients with RAML managed with transarterial embolization. Mortality has not developed in this patient group depending on the embolization. Tumor size reduction of 38.3% (mean 3.4 cm) was determined at average 39-month follow-up after embolization. Unplanned embolization or surgery was necessitated in 20.9% of patients during follow up period. Re-operation etiology includes RAML revascularization (30%), constant or increasing tumor size (22.6%), refractory or recurrent symptoms (16.7%) and the emergence of acute retroperitoneal hemorrhage (14.3%) 9.
According to the European Association of Urology (EAU) guidelines, active surveillance would be the most appropriate approach for RAML [Grade of Evidence (GE): 3].
Selective arterial embolization is recommended as first-line therapy whether active monitoring will be discontinued (GE: 3). If surgical treatment is preferred, many patients can be managed by NSS, complete nephrectomy is indicated in some patients (GE: 3). Radiofrequency ablation can be used as another option. Moreover the tumor volume can be reduced with mTOR inhibitors (sirolimus and everolimus) and surgery may be delayed with this treatment 10.