Rigi10™ Malleable Penile Prosthesis
Also Known As
Renal angiomyolipoma (AML), Kidney angiomyolipoma, Renal AML, Kidney AML, Renal hamartoma (though technically distinct)
Definition
Angiomyolipoma is a benign kidney tumor characterized by a composition of blood vessels, smooth muscle, and fat tissue in varying amounts.1 It belongs to the family of perivascular epithelioid cell tumors (PEComas) and is distinguished by its perivascular epithelioid differentiation.2 These tumors are typically well-circumscribed and can vary in size from a few millimeters to over 20 centimeters in diameter.3 Although considered benign, angiomyolipomas can grow significantly and may cause complications through mass effect or spontaneous hemorrhage due to the presence of abnormal blood vessels with microaneurysms.4 Angiomyolipomas can manifest as fat-rich (most common), fat-poor, or fat-invisible masses, with approximately 5% belonging to the fat-poor or fat-invisible variety, which presents diagnostic challenges.5
Clinical Context
Angiomyolipomas are clinically significant in both sporadic and hereditary contexts. The majority (80%) occur sporadically, while 20% are associated with genetic conditions, primarily tuberous sclerosis complex (TSC) and pulmonary lymphangioleiomyomatosis (LAM).1
In clinical practice, angiomyolipomas are often discovered incidentally during imaging studies performed for unrelated reasons.2 However, symptomatic presentations may include flank pain, palpable mass, urinary tract infections, hematuria, renal failure, or hypertension.3 The most concerning clinical presentation is spontaneous retroperitoneal hemorrhage, which can be life-threatening and is more common in tumors larger than 4 cm in diameter.4
Patient selection for intervention is based on several factors including tumor size, symptoms, risk of complications, and associated conditions. For small (<4 cm), asymptomatic angiomyolipomas, active surveillance with periodic imaging is typically recommended.2 For larger tumors, symptomatic lesions, or those at high risk of bleeding, intervention may be warranted.5
Treatment options include:
- Active surveillance with periodic imaging for small, asymptomatic tumors
- Selective arterial embolization for bleeding control or to reduce tumor size
- Nephron-sparing surgery (partial nephrectomy) for selected cases
- Pharmacological therapy with mammalian target of rapamycin (mTOR) inhibitors such as sirolimus or everolimus, particularly for patients with tuberous sclerosis complex4
For patients with tuberous sclerosis complex, screening for renal angiomyolipomas is recommended, as these patients often develop multiple, bilateral tumors that may require earlier intervention.1 Similarly, patients with lymphangioleiomyomatosis should undergo renal imaging to screen for angiomyolipomas.5