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Typical Kidney Tumor With Atypical Presentation

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

A White woman in her late 50s with a medical history of osteoporosis, hyperlipidemia, and migraines presented with hematuria. Results of computed tomography (CT) imaging showed an 8×6×5-cm right kidney lesion (Figure 1, A). The patient underwent surgical resection with a right nephrectomy and an apparent diagnosis of angiomyolipoma (AML). One year later, the patient underwent excision of a right iliac wing lesion, and pathologic findings demonstrated xanthoma of bone with sclerosis. Three years after this second surgery, she presented with new abdominal pain. Results of CT imaging revealed a 4.3-cm retrocaval mass at the level of the renal right vein. She underwent surgical resection, and results of pathologic evaluation were consistent with the original tumor. Follow-up CT imaging revealed a 1.2-cm left upper lobe lung nodule and a 0.8-cm right upper lobe lung nodule, as well as a pulmonary embolism and a left 6th rib fracture. These lesions were fluorodeoxyglucose-positron emission tomography avid. The patient denied constitutional symptoms such as fatigue, fever, chills, and night sweats. She underwent bilateral video-assisted thoracoscopic surgery wedge resections of the lung lesions, which were also consistent with the primary tumor. Five years later, the patient (now in her late 60s) presented with multiple left pleural-based lung lesions (Figure 1, B). Results of all laboratory testing were within reference ranges. These pleural-based lesions were resected with left video-assisted thoracoscopic surgery partial pleurectomy, and results of pathologic evaluation were positive for HMB45 and Melan-A.

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A. Epithelioid angiomyolipoma

This patient has metastatic epithelioid angiomyolipoma (EAML), an unusual variant of AML, which is among the most commonly encountered types of kidney masses. The resected masses were consistent with an epithelioid mesenchymal neoplasm with clear cell morphology having low to intermediate grade features (low mitotic rate with focal tumor necrosis; Figure 2). The diagnosis of EAML was confirmed with HMB45 and Melan-A staining.

Perivascular epithelioid cell neoplasms (PEComas) is a family of related mesenchymal tumors, including AML, lymphangiomyomatosis, clear cell tumors of the lung, and rare morphologically and immunophenotypically similar tumors.1 These tumors are defined by perivascular epithelioid cells or spindle cells with clear eosinophilic cytoplasm and are typically arranged around blood vessels with immunoreactivity to smooth muscle and melanocytic (HMB5 and Melan-A) markers.2 Typically, PEComa tumors occur at visceral, retroperitoneal, and abdominopelvic sites (the uterus being the most common site)3 and are rarely malignant (only 6% to 7% demonstrate distant metastasis).1

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Article Information

Corresponding Author: Chuong D. Hoang, MD, Thoracic Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg 10-CRC, Room 4-3952, Bethesda, MD 20892 (chuong.hoang@nih.gov).

Published Online: June 17, 2021. doi:10.1001/jamaoncol.2021.1707

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient for granting permission to publish this information.

Hornick  JL , Fletcher  CDM .  PEComa: what do we know so far ?  Histopathology. 2006;48(1):75-82. doi:10.1111/j.1365-2559.2005.02316.x PubMedGoogle ScholarCrossref
Thway  K , Fisher  C .  PEComa: morphology and genetics of a complex tumor family.   Ann Diagn Pathol. 2015;19(5):359-368. doi:10.1016/j.anndiagpath.2015.06.003 PubMedGoogle ScholarCrossref
Bennett  JA , Braga  AC , Pinto  A ,  et al.  Uterine PEComas: a morphologic, immunohistochemical, and molecular analysis of 32 tumors.   Am J Surg Pathol. 2018;42(10):1370-1383. doi:10.1097/PAS.0000000000001119 PubMedGoogle ScholarCrossref
Vos  N , Oyen  R .  Renal angiomyolipoma: the good, the bad, and the ugly.   J Belg Soc Radiol. 2018;102(1):41. doi:10.5334/jbsr.1536 PubMedGoogle ScholarCrossref
Akumalla  S , Madison  R , Lin  DI ,  et al.  Characterization of clinical cases of malignant PEComa via comprehensive genomic profiling of DNA and RNA.   Oncology. 2020;98(12):905-912. doi:10.1159/000510241 PubMedGoogle ScholarCrossref
Park  SG , Park  BK .  New radiologic classification of renal angiomyolipoma: frequently asked questions.   Clin Imaging. 2019;55:156-160. doi:10.1016/j.clinimag.2019.01.025 PubMedGoogle ScholarCrossref
Flum  AS , Hamoui  N , Said  MA ,  et al.  Update on the diagnosis and management of renal angiomyolipoma.   J Urol. 2016;195(4 Pt 1):834-846. doi:10.1016/j.juro.2015.07.126 PubMedGoogle Scholar
Wagner  AJ , Ravi  V , Ganjoo  KN ,  et al.  ABI-009 (nab-sirolimus) in advanced malignant perivascular epithelioid cell tumors (PEComa): Preliminary efficacy, safety, and mutational status from AMPECT, an open label phase II registration trial.   J Clin Oncol. 2019;37(15 suppl):11005-11005. doi:10.1200/JCO.2019.37.15_suppl.11005Google Scholar
Lei  JH , Liu  LR , Wei  Q ,  et al.  A four-year follow-up study of renal epithelioid angiomyolipoma: a multi-center experience and literature review.   Sci Rep. 2015;5:10030. doi:10.1038/srep10030 PubMedGoogle ScholarCrossref
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Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

  • 1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
  • 1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
  • 1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
  • 1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
  • 1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.

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