Arch Pathol Lab Med—Vol 129, May 2005
Atypical Angiomyolipoma of Kidney
—Ma et al
Atypical Angiomyolipoma of Kidney in a Patient With
A Case Report With
Gene Mutation Analysis
Linglei Ma, MD, PhD; Diane Kowalski, MD; Khurram Javed, BS; Pei Hui, MD, PhD
Angiomyolipoma (AML) is the most common benign
mesenchymal tumor of the kidney. It belongs to the family
of perivascular epithelioid cell tumors and is typically com-
posed of blood vessels, adipose tissue, and smooth muscle–
like cells, which are characteristically positive for HMB-
45. Results of recent studies suggest that
play an important role in AML progression. Here, we de-
scribe a locally destructive renal AML in a patient with
tuberous sclerosis. The tumor consisted of mostly epithe-
lioid cells with marked nuclear pleomorphism and frequent
mitoses and was positive for HMB-45. The diagnosis of
atypical epithelioid AML was made. Codon alteration in
gene was not detected, despite focal p53 immu-
noreactivity and single nucleotide polymorphism at exon
6. Our ﬁnding indicates no deﬁnite link between
normalities and the atypical appearance of AML. To the
best of our knowledge, this is the second renal AML case
Arch Pathol Lab Med.
enal angiomyolipoma (AML) is the most common
mesenchymal tumor of the kidney. It is composed of
variable proportions of thick-walled blood vessels, adi-
pose tissue, and smooth muscle–like cells. More than 40%
of renal AMLs are associated with tuberous sclerosis.
laterality and multicentricity are features closely tied to
the tuberous sclerosis complex. AMLs frequently display
a loss of heterozygosity at the region containing tuberous
sclerosis complex genes in tuberous sclerosis–associated
and sporadic tumors.
AMLs can also involve extrarenal
organs, most commonly the liver.
In typical AMLs, the smooth muscle–like cells form
mainly fascicles of spindle cells. In 1991, the epithelioid
variant of AMLs was described, following the discovery
of HMB-45 (melanosome-associated protein) reactivity in
The smooth muscle–like cells in this variant are
characterized by a predominantly epithelioid morphology.
A subgroup of epithelioid AMLs display marked pleo-
Accepted for publication December 6, 2004.
From the Department of Pathology, Yale University School of Medi-
cine, New Haven, Conn.
The authors have no relevant ﬁnancial interest in the products or
companies described in this article.
Reprints: Pei Hui, MD, PhD, Department of Pathology, Yale Univer-
sity School of Medicine, 310 Cedar St, New Haven, CT 06510 (e-mail:
morphism and are called atypical AMLs.