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==Overview==
==Overview==
==Pathophysiology==
==Pathophysiology==
 
Three components of an angiomyolipoma include:
==Gross==
*Vascular cells
*Well circumscribed - uniform yellow.
*Immature [[smooth muscle cells]]
 
*Fat cells
Since all three components of an angiomyolipoma (vascular cells, immature [[smooth muscle cells]] and fat cells) contain a "second hit" mutation, they are believed to have derived from a common [[progenitor cell]] that suffered the common second hit mutation. [[Angiomyolipoma]]s are members of the perivascular epithelioid cells tumour group (PEComas) and are composed of variable amounts of three components;[[blood vessels]] (-angio), plump [[spindle cells]] (-myo) and [[adipose tissue]] (-lipo). Almost all classic angiomyolipomas are benign but they do have the risk of rupture with bleeding or secondary damage/destruction of surrounding structures as they grow.
They are derived from a common [[progenitor cell]] that suffered the common second hit mutation. [[Angiomyolipoma]]s are members of the perivascular epithelioid cells tumour group (PEComas) and are composed of variable amounts of three components:
 
*[[blood vessels]] (-angio)
*plump [[spindle cells]] (-myo)
*[[adipose tissue]] (-lipoma)
===Pathology===
===Gross===
*Well circumscribed - uniform yellow
===Variants===
===Variants===
 
*Epithelioid angiomyolipoma
There is a special variant called an epithelioid angiomyolipoma, composed of more plump, epithelial looking cells, often with nuclear atypia, that have a described risk of malignant behaviour. This variant, unlike conventional AMLs, may mimic [[renal cell carcinoma]].10 Metastases have also been described 9.
There is a special variant called an epithelioid angiomyolipoma, composed of more plump, epithelial looking cells, often with nuclear atypia, that have a described risk of malignant behaviour.
 
===Microscopic Pathology===
===Microscopic Pathology===
===Microscopic===
Features:
Features:
*Smooth muscle.
*Smooth muscle.

Revision as of 14:02, 23 September 2015

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2], Faizan Sheraz, M.D. [3]

Overview

Pathophysiology

Three components of an angiomyolipoma include:

They are derived from a common progenitor cell that suffered the common second hit mutation. Angiomyolipomas are members of the perivascular epithelioid cells tumour group (PEComas) and are composed of variable amounts of three components:

Pathology

Gross

  • Well circumscribed - uniform yellow

Variants

  • Epithelioid angiomyolipoma

There is a special variant called an epithelioid angiomyolipoma, composed of more plump, epithelial looking cells, often with nuclear atypia, that have a described risk of malignant behaviour.

Microscopic Pathology

Features:

  • Smooth muscle.
  • Adipose tissue - not always present[1] - key feature.
  • Abundant blood vessels.

1. Histopathologic image of renal angiomyolipoma. Nephrectomy specimen. H & E stain. 2. Histopathologic image of renal angiomyolipoma. Nephrectomy specimen. The same case as demonstrated in "Image 1". H & E stain. 3. Histopathologic image of renal angiomyolipoma. Nephrectomy specimen. The same case as demonstrated in "Image 1". H & E stain. 4. Histopathologic image of renal angiomyolipoma. Nephrectomy specimen. The same case as demonstrated in "Image 1". HMB-45 immunostain.

Cytologic

Features[1]

  • Nuclei - round/ovoid.
  • Chromatin - bland.==IHC==
  • Melanocytic markers +ve.[2]
    • HMB-45 +ve in all cases (15/15).[3]
    • Melan A +ve in ~87% of cases (13/15).
  • Epithelial markers -ve[2], e.g. EMA and AE1/AE3.
  • SMA +ve.
  • CD117 +ve/-ve.
  • Ki-67:[4]
    • Epithelioid variant of AML +ve.
    • Conventional AML -ve.


References

  1. 1.0 1.1 Crapanzano, JP. (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. Unknown parameter |month= ignored (help)
  2. 2.0 2.1 Template:Ref GUP
  3. Esheba, Gel S.; Esheba, Nel S. (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. Unknown parameter |month= ignored (help)
  4. 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.

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