Angiomyolipoma

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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), Xp11.2 translocation carcinoma (esp. for epithelioid variant), well-differentiated retroperitoneal sarcoma (esp. leiomyosarcoma & liposarcoma), renal cell carcinoma with sarcomatoid differentiation
IHC HMB-45 +ve, Melan A +ve, SMA +ve, PAX8 -ve, CK (pooled) -ve
Site kidney (see kidney tumours), other sites
Syndromes tuberous sclerosis
Prevalence uncommon
Radiology classically has regions consistent with fat
Prognosis benign, epithelioid variant may be aggressive
Clin. DDx other kidney tumours
Treatment surgery - esp. if large or imaging characteristics ambiguous

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.

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.

DDx:

Images

  • AML (WC).

  • AML (WC/KGH).

  • AML (WC/KGH).

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.[9]
    • HMB-45 +ve in all cases (15/15).[10]
    • Melan A +ve in ~87% of cases (13/15).
  • Epithelial markers -ve[9], e.g. EMA and AE1/AE3.
  • SMA +ve.
  • CD117 +ve/-ve.
  • Ki-67:[11]
    • Epithelioid variant of AML +ve.
    • Conventional AML -ve.

A panel:

  • CK (pooled), Desmin, Melan A, HMB-45.

Epithelioid AML versus Xp11.2 translocation carcinoma

ISUP recommends:[12]

  • PAX8 -ve.
    • Positive in Xp11.2 translocation carcinoma.
  • CAIX -ve.
  • AE1/AE3 -ve.
  • EMA -ve.

Sign out

RIGHT KIDNEY, PARTIAL NEPHRECTOMY:
- ANGIOMYOLIPOMA.

Micro

The section show a circumscribed tumour composed of muscle-like tissue and adipose tissue with prominent muscular blood vessels. Rare nuclear enlargement is seen. No signficant nuclear atypia is appreciated. Mitotic activity is not apparent.

Biopsy

MASS OF LEFT KIDNEY, CORE BIOPSY:
- COMPATIBLE WITH ANGIOMYOLIPOMA.

COMMENT:
The tumour stains as follows:
POSITIVE: Melan A, HMB-45, desmin.
NEGATIVE: CK (pooled).

Micro

The sections show a tumour composed of spindle cells in a fasicular arrangement with scant adipose tissue and prominent muscular blood vessels. Rare nuclear enlargement is seen. No signficant nuclear atypia is appreciated. Mitotic activity is not apparent. No renal parenchyma is identified.

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. ↑ Williamson, SR.; Cheng, L.; Eble, JN.; True, LD.; Gupta, NS.; Wang, M.; Zhang, S.; Grignon, DJ. (Sep 2014). "Renal cell carcinoma with angioleiomyoma-like stroma: clinicopathological, immunohistochemical, and molecular features supporting classification as a distinct entity.". Mod Pathol. doi:10.1038/modpathol.2014.105. PMID 25189644.
  8. ↑ 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.
  9. ↑ 9.0 9.1 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.
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ Amin MB, Epstein JI, Ulbright TM, et al. (August 2014). "Best practices recommendations in the application of immunohistochemistry in urologic pathology: report from the international society of urological pathology consensus conference". Am. J. Surg. Pathol. 38 (8): 1017–22. doi:10.1097/PAS.0000000000000254. PMID 25025364.
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