00:00 / 00:00




Renal system




0 / 9 complete

USMLE® Step 1 questions

0 / 2 complete

High Yield Notes

9 pages



of complete


USMLE® Step 1 style questions USMLE

of complete

A 5-year-old child with intellectual disability is brought to the clinic by his parents due to progressive growth of facial lesions. His parents first noted it a few months ago and tried several over-the-counter creams with minimal improvement. Medical history is notable for seizures, hyperactivity, and mild cognitive dysfunction. Vitals are within normal limits. Physical examination reveals the facial lesions shown below:  

Reproduced from: Wikipedia    

Which of the following additional findings is most likely to be found on further examination of this patient?    


Content Reviewers

Angiomyolipomas are the most common benign tumors found in the kidneys, although they can be found in other tissues like the liver and on rare occasions in some reproductive structures.

If we break down the word we see that they are tumors that are comprised of blood vessels (angio), smooth muscle (myo), and adipose or fat tissue (lipo).

Angiomyolipomas are often described as hamartomas, which means that they are focal, abnormal growth of cells which are normally found at that site, but are disorganized.

It’s a bit like a house with a front door that can’t be reached, it’s the right part for the structure, but it’s not organized in the right way.

Angiomyolipomas also belong to the perivascular epithelioid cell tumor family, or PEComa family, meaning that they are made of epithelial-like cells that are found around blood vessels.

Now, it’s worth mentioning that normally there are no perivascular epithelioid cells that exist; the name just refers to the way that the tumor cells look under the microscope.

The actual cell type from which PEComas, including angiomyolipomas arise, is not known.

The majority of angiomyolipomas will pop up sporadically - which means they are not a part of a syndrome - as isolated lesions.

Interestingly, the tumors develop more often in the right kidney than in the left.

However, these tumors are also strongly associated with tuberous sclerosis which is a genetic disease that causes benign tumors to develop in various parts of the body.

Individuals with tuberous sclerosis often have multiple angiomyolipomas along the surface of both kidneys, and they can be larger in size than the sporadic ones.

Regardless of whether the angiomyolipoma occurs sporadically or as a consequence of tuberous sclerosis, there is usually an underlying mutation in one of the tuberous sclerosis genes - TSC1 or TSC2 - which code for the tuberous sclerosis complex proteins hamartin and tuberin, respectively.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "The Differential Imaging Features of Fat-Containing Tumors in the Peritoneal Cavity and Retroperitoneum: the Radiologic-Pathologic Correlation" Korean Journal of Radiology (2010)
  6. "Tuberous Sclerosis Complex Diagnostic Criteria Update: Recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference" Pediatric Neurology (2013)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.