Factors associated with the number and size of renal angiomyolipomas in sporadic angiomyolipoma (sAML): a study of adult patients with sAML managed in a Dutch tertiary referral center.

Purpose: To describe the patient characteristics, treatments, disease monitoring, and kidney function of patients with sporadic angiomyolipoma (sAML), stratified by the number and size of renal angiomyolipomas (AMLs).

Methods: Single-center retrospective analysis of patients with sAML treated from 1990 to 2015 in a dedicated clinic for inheritable tumor syndromes in a tertiary referral center from the Netherlands. Patients' first AML assessment at the clinic was defined as the index date. Patient characteristics were measured at the index date. Treatments, disease monitoring, and kidney function were measured post-index date.

Results: The study sample included 53 patients followed for a total of 184.6 patient-years. At the index date, the largest AML was ≥ 3.5 cm for 26 patients and < 3.5 cm for 27 patients (including six patients with five or more AMLs of < 3.5 cm). As compared to patients with AMLs < 3.5 cm, patients with largest AML ≥ 3.5 cm had higher frequency of pre-index bleeding episodes (31 vs. 4%), pre-index hypertension (35 vs. 15%), post-index nephrectomy (19 vs. 4%), post-index embolization (8 vs. 0%), and post-index renal scans (1.14 vs. 0.74 scans/year). Kidney impairment was especially pronounced in young adults with AML ≥ 3.5 cm. On average, patients with sAML developed chronic kidney disease stage two earlier than the general Dutch population (age 42 vs. 55 years), but later than the patients with tuberous sclerosis complex (35 years).

Conclusions: Patients with sAML, especially those with larger AMLs, have high disease burden.