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A 28-year-old Hispanic woman presented to a nephrology clinic after a complicated pregnancy that resulted in a delivery a few weeks before term due to a diagnosis of preeclampsia.Her ob/gyn wanted her evaluated for a possible underlying chronic glomerulopathy or other kidney disease. This was her third pregnancy and the previous two had been uncomplicated. She reported no significant medical history and was taking no medications except prenatal vitamins and ferrous sulfate. She had no knowledge of family history of kidney disease. She was evaluated four weeks after delivery.On exam, her blood pressure was 112/94 mm Hg. She had multiple, small, orange papules around her nose. She was mildly obese. Kidneys were palpable bilaterally but non-tender. Her creatinine level was 1.1 mg/dL. At the time of delivery she had 3.4 grams of protein on a 24-hour specimen. Urine showed no blood and minimal pyuria. Ultrasound of the kidneys was performed (see image).
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Answer: Tuberous sclerosis
Tuberous sclerosis (TS) is a rare genetic disease characterized by formation of benign neoplastic growths, angiomyolipomas, in various organs including brain, eye, kidney and skin. It very rarely causes end-stage kidney disease.
TS is diagnosed based on presence of major and minor criteria. Major criteria include facial angiofibromas, periungual fibromas, hypomelanotic skin nodules, shagreen patch, retinal hamartomas, cortical tuber, subependymal nodules/giant cell astrocytomas, cardiac rhabdomyoma, lymphangiomyomatosis, and renal angiomyolipiomas. Minor criteria include dental enamel pits, hamartomatous rectal polyps, bone cysts, cerebral white matter migration lines, gingival fibromas, multiple renal cysts, other non-renal hamartomas, retinal achromic patch, and “confetti” skin lesions.
A definitive diagnosis can be assigned with either two major criteria, or one major plus two minor criteria. A probable diagnosis can be assigned with one major plus one minor criteria. The patient in this case had a brain computed tomography scan without contrast ordered by another physician (see image).
The image demonstrates a calcified sub-centimeter subependymal nodule along the margins of the left lateral ventricle. There were also multiple low-density lesions throughout the cortical/subcortical areas that were consistent with TS (image not shown).
Approximately 60%-80% of TS patients will have a renal lesion. The majority of these lesions are angiomyolipomas that are echogenic and have a density of about -10 to -100 Hounsfield units, consistent with fatty components. A minority of TS patients will present with multiple renal cysts on imaging, which may mimic polycystic kidney disease.TS is autosomal dominantly inherited, though there can be sporadic cases. Genetic defects map to TSC-1 gene on chromosome 9 and TSC-2 gene on chromosome 16 that produce hamartin and tuberin proteins, respectively.
Genetic testing for mutations is available. The ultrasound on our particular patient showed right and left kidneys that both measured over 16 cm. There were multiple cysts bilaterally many with internal septations, and twinkling artifact consistent with calcification. She was referred for a CT scan of abdomen and pelvis and for genetic analysis.
This clinical case was prepared by Kevin T. Harley, MD, Assistant Clinical Professor of Medicine at the University of California in Irvine.
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