An unusual case of multiple bilateral kidney tumors
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NEPHROLOGY PICTURE
An unusual case of multiple bilateral kidney tumors Aghilès Hamroun1,2 · Rémi Lenain1 · François Provôt1 · Mehdi Maanaoui1,3 · Arnaud Lionet1 Received: 7 October 2020 / Accepted: 13 October 2020 © Italian Society of Nephrology 2020
Keywords Oncocytoma · Renal cell carcinoma · Shagreen patch · Tuberous sclerosis complex A 39-year-old patient with no medical history other than childhood absence epilepsy treated with sodium valproate wasreferred to our nephrology department for chronic kidney disease (serum creatinine at 4.2 mg/dl). The etiological evaluation revealed major bilateral kidney infiltration by multiple tumors: uro -MRI revealed the presence of 20 chromophobe tumors, the largest of which measuring 14 cm within the right kidney (Fig. 1a, b). A binephrectomy was rapidly scheduled, after preparation for hemodialysis. Histological examination confirmed the diagnosis of multiple bilateral hybrid oncocytic/chromophobe tumors, with the presence of a papillary renal cell carcinoma in the left kidney. Due to bilateral renal involvement as well a the number and nature of the tumor lesions, ‘Birt-Hogg-Dube’ syndrome was the first hypothesis. However, this diagnosis was exclude by the absence of FLCN gene mutation. Detailed physical examination revealed shagreen patch lesion in the lumbar region (Fig. 1c) as well as two periungual fibromas (Fig. 1d). Brain MRI was performed given the history of epilepsy, and indicated the presence of cortical lesions suggestive of tubers and subependymal nodules. Altogether these findings led us to the diagnosis of tuberous sclerosis complex (TSC), als confirmed by the detection of a TSC1 gene mutation (c.1041G > A). There was no particular medical history in the family, the patient being an only child. TSC is a multisystem autosomal dominant genetic disorder
due to unregulated activation of the mammalian target of rapamycin (mTOR) pathway, resulting in the growth of hamartomas in multiple organs. The highly heterogeneous clinical manifestations often make the diagnosis particularly challenging. Typical skin involvement, present in more than 90% of cases, represents one of the major diagnostic criteria [1]. In our case, the delay in diagnosis is notably due to the skin involvement, as well as the absence of renal angiomyolipomas and brain imaging at the diagnosis of epilepsy. Although angiomyolipoma is the most common TSC-associated renal tumor (more than 80% of cases), the presence of hybrid oncocytic/chromophobe tumors and papillary renal cell carcinomas is increasingly recognized as a part of the syndrome [2]. Further evaluation did not show any evidence of cardiac or pulmonary involvement. After 3 years of cancer free follow-up, enrollment in the kidney transplant waiting list is currently under evaluation. Of note, the cutaneous lesions regressed under topical treatment with sirolimus (mTOR inhibitor). Our case suggests that TSC should systematically be suspected in case of multiple kidney tumors.
* Aghilès Hamroun [email protected] 1
Nephr
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