Angiomyolipoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2] Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [3], Faizan Sheraz, M.D. [4]
Overview
On gross pathology, well circumscribed and uniform yellow mass is characteristic finding of angiomyolipoma. The components of an angiomyolipoma include vascular cells, immature smooth muscle cells and fat cells.
Pathophysiology
Three components of an angiomyolipoma include:
- Vascular cells
- Immature smooth muscle cells
- Fat cells
They are derived from a common progenitor cell that suffered the common second hit mutation. Angiomyolipomas are members of the perivascular epithelioid cells tumor group (PEComas) and are composed of variable amounts of three components:
- Blood vessels (-angio)
- Plump Spindle cells (-myo)
- Adipose tissue (-lipoma)
Genetics
Angiomyolipoma is caused by a defect in the TSC1 and TSC2 gene.
Associated Conditions
Diseases associated with angiomyolipoma include:
Gross Pathology
On gross pathology, well circumscribed and uniform yellow mass are characteristic findings of angiomyolipoma.
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
Microscopic features of angiomyolipoma:
- Smooth muscle
- Adipose tissue - not always present[2] - key feature
- Abundant blood vessels
Cytologic
Cytologic features of angiomyolipoma include:[2]
Immunohistochemistry
Immunohistochemistry markers of angiomyolipoma include:
- Melanocytic markers positive[3]
- HMB-45 positive in all cases (15/15)[4]
- Melan A positive in ~87% of cases (13/15)
- Epithelial markers negative[3]
- EMA
- AE1/AE3
- SMA positive
- CD117 positive/negative
- Ki-67:[5]
- Epithelioid variant of angiomyolipoma positive
- Conventional angiomyolipoma negative
References
- ↑ Image courtesy of Dr Andrew Ryan. Radiopaedia (original file [1]).[http://radiopaedia.org/licence Creative Commons BY-SA-NC
- ↑ 2.0 2.1 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
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ignored (help) - ↑ 3.0 3.1 Template:Ref GUP
- ↑ 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
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ignored (help) - ↑ 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.