Abdomen / Pelvis for Thursday, April 10th, 2025

History

14 yo Female presents with abdominal pain and gross hematuria

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Question

What is the diagnosis, including the genetic syndrome?

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Correct answer

Angiomyolipoma in the setting of tuberous sclerosis associated with autosomal dominant polycystic kidney disease (TSC2/PPKD1 contiguous deletion syndrome)

Discussion

This was a case of angiomyolipoma in the setting of tuberous sclerosis (TSC) associated with autosomal dominant polycystic kidney disease (ADPKD) due to TSC2 / PKD1 contiguous gene deletion. 

TSC is caused by pathogenic variants in either TSC1 or TSC2, encoding hamartin and tuberin, respectively. T2C2 is immediately adjacent to PKD1 gene (encoding polycystin-1 and causing ADPKD) on chromosome 16p13.3 and large deletions can result in TSC2/PKD1 contiguous gene deletion syndrome. This occurs in about 2-3% of TSC patients.

Angiomyolipomas is a type of perivascular epithelioid cell tumor (PEComa) and can be found in 55%–75% of patients
with TSC. AMLs can be lipid rich, lipid poor, or lipid invisible. Pathognomonic macroscopic fat in lipid rich AMLs can be idenitified on CT by the presence of fat (<-10 H.U.), or on MRI with signal loss on fat-saturation or with india-ink artifact on chemical shift imaging. AMLs can also have microsopic fat with signal drop on out of phase images. 

Renal AMLs can hemorrhage and rupture. Thus, mTOR inhibitors are started for AML > 3 cm and/or history of AML requiring embolization/nephrectomy. Embolization or nephron-sparing surgery are recommended for AMLs > 4 cm or with aneurysms > 5mm.  

In this case, this patient's renal AML was ~5 cm in size and was associated with gross hematuria. IR successfully embolized the right AML and associated pseudoaneurysm. She will continue yearly surveillance MRIs. 

Differential diagnosis

• Hemorrhagic or proteinaceous cyst
• Renal cell carcinoma
• Von-Hippel Lindau syndrome

Additional images

References

• Nair, N., Chakraborty, R., Mahajan, Z., Sharma, A., Sethi, S. K., & Raina, R. (2020). Renal manifestations of tuberous sclerosis complex. Journal of Kidney Cancer and VHL, 7(3), 5.
• Wang, M. X., Segaran, N., Bhalla, S., Pickhardt, P. J., Lubner, M. G., Katabathina, V. S., & Ganeshan, D. (2021). Tuberous sclerosis: current update. Radiographics, 41(7), 1992-2010.
• Manoukian, S. B., & Kowal, D. J. (2015). Comprehensive imaging manifestations of tuberous sclerosis. American Journal of Roentgenology, 204(5), 933-943.
• Osumi, Keita, et al. "Molecular diagnosis of an infant with TSC2/PKD1 contiguous gene syndrome." Human genome variation 7.1 (2020): 21.