Angiomyolipoma

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Angiomyolipoma, abbreviated AML, is a benign mesenchymal tumour that is associated with tuberous sclerosis and belongs to the PEComa group of tumours. It is typically found in the kidney.

Angiomyolipoma
Diagnosis in short

Angiomyolipoma. H&E stain.

LM smooth muscle, adipose tissue (not always present), abundant blood vessels.
Subtypes conventional, epithelioid angiomyolipoma
LM DDx clear cell renal cell carcinoma (esp. for epithelioid variant)
IHC HMB-45 +ve, Melan A +ve, SMA +ve
Site kidney - see kidney tumours

Syndromes tuberous sclerosis

Prevalence uncommon
Radiology classically has regions consistent with fat
Prognosis benign, epithelioid variant may be aggressive
Clin. DDx other kidney tumours

General

  • Benign mesenchymal tumour.
  • Presentations: flank pain, hematuria, incidentaloma.[1]
    • Tumours >4 cm considered a risk for bleeding.[2]
  • AMLs occur may be elsewhere in the body, e.g. liver,[3] but are most common in the kidney.
  • In the PEComa group of tumours.

Epidemiology

  • May be associated with tuberous sclerosis -- 70% have an AML.
    • When compared to sporadic cases:
      • More often bilateral.
      • Usually bigger.
  • There is a suggestion that an epithelioid variant is more worrisome.[4]
    • This is not confirmed by all studies.[5]

Microscopic

Features:

  • Smooth muscle.
  • Adipose tissue - not always present[6] - key feature.
  • Abundant blood vessels.

Images

Epithelioid angiomyolipoma

Features:

  • Carcinoma-like morphology.
  • +/-Spindle cells.
  • "High grade" nuclei.
    • Pleomorphic nuclei.

DDx:

Images:

Cytologic

Features[6]

  • Nuclei - round/ovoid.
  • Chromatin - bland.

IHC

  • Melanocytic markers +ve.[8]
    • HMB-45 +ve in all cases (15/15).[9]
    • Melan A +ve in ~87% of cases (13/15).
  • Epithelial markers -ve.[8]
  • SMA +ve.
  • CD117 +ve/-ve.
  • Ki-67:[10]
    • Epithelioid variant of AML +ve.
    • Conventional AML -ve.

See also

References

  1. Seyam, RM.; Bissada, NK.; Kattan, SA.; Mokhtar, AA.; Aslam, M.; Fahmy, WE.; Mourad, WA.; Binmahfouz, AA. et al. (Nov 2008). "Changing trends in presentation, diagnosis and management of renal angiomyolipoma: comparison of sporadic and tuberous sclerosis complex-associated forms.". Urology 72 (5): 1077-82. doi:10.1016/j.urology.2008.07.049. PMID 18805573.
  2. Abrams, J.; Yee, DC.; Clark, TW. (Jul 2011). "Transradial embolization of a bleeding renal angiomyolipoma.". Vasc Endovascular Surg 45 (5): 470-3. doi:10.1177/1538574411408352. PMID 21571778.
  3. Zhang, SH.; Cong, WM.; Xian, ZH.; Wu, WQ.; Dong, H.; Wu, MC. (Oct 2004). "[Morphologic variants and immunohistochemical features of hepatic angiomyolipoma.]". Zhonghua Bing Li Xue Za Zhi 33 (5): 437-40. PMID 15498214.
  4. Nelson, CP.; Sanda, MG. (Oct 2002). "Contemporary diagnosis and management of renal angiomyolipoma.". J Urol 168 (4 Pt 1): 1315-25. doi:10.1097/01.ju.0000028200.86216.b2. PMID 12352384.
  5. Aydin, H.; Magi-Galluzzi, C.; Lane, BR.; Sercia, L.; Lopez, JI.; Rini, BI.; Zhou, M. (Feb 2009). "Renal angiomyolipoma: clinicopathologic study of 194 cases with emphasis on the epithelioid histology and tuberous sclerosis association.". Am J Surg Pathol 33 (2): 289-97. doi:10.1097/PAS.0b013e31817ed7a6. PMID 18852677.
  6. 6.0 6.1 Crapanzano, JP. (Jan 2005). "Fine-needle aspiration of renal angiomyolipoma: cytological findings and diagnostic pitfalls in a series of five cases.". Diagn Cytopathol 32 (1): 53-7. doi:10.1002/dc.20179. PMID 15584043.
  7. Aljerian, K.; Evans, AJ. (Oct 2004). "Pathologic quiz case: a 44-year-old woman with an incidental asymptomatic renal mass. Atypical epithelioid angiomyolipoma.". Arch Pathol Lab Med 128 (10): 1176-8. doi:10.1043/1543-2165(2004)1281176:PQCAYW2.0.CO;2. PMID 15387699.
  8. 8.0 8.1 Zhou, Ming; Magi-Galluzzi, Cristina (2006). Genitourinary Pathology: A Volume in Foundations in Diagnostic Pathology Series (1st ed.). Churchill Livingstone. pp. 324. ISBN 978-0443066771.
  9. Esheba, Gel S.; Esheba, Nel S. (Sep 2013). "Angiomyolipoma of the kidney: clinicopathological and immunohistochemical study.". J Egypt Natl Canc Inst 25 (3): 125-34. doi:10.1016/j.jnci.2013.05.002. PMID 23932749.
  10. Ooi, SM.; Vivian, JB.; Cohen, RJ. (2009). "The use of the Ki-67 marker in the pathological diagnosis of the epithelioid variant of renal angiomyolipoma.". Int Urol Nephrol 41 (3): 559-65. doi:10.1007/s11255-008-9473-1. PMID 18839327.