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Clear Cell Myomelanocytic Tumor of the Falciform Ligament/Ligamentum
Teres A Novel Member of the Perivascular Epithelioid Clear Cell Family
of Tumors With a Predilection for Children and Young Adults
Andrew L. Folpe, M.D.; Zachary D. Goodman, M.D.; Kamal G. Ishak,
M.D.; Augusto F. G. Paulino, M.D.; Eugenio M. Taboada, M.D.; Shane A.
Meehan, M.D.; Sharon W. Weiss, M.D. Okuda K, Peter R, eds.
From the Department of Pathology and Laboratory Medicine, Emory
University, Atlanta, Georgia, U.S.A. (A.L.F., S.W.W.); Departments of
Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology,
Washington, D.C., U.S.A. (Z.D.G., K.G.I.); Department of Pathology,
University of Michigan Hospitals, Ann Arbor, Michigan, U.S.A. (A.F.G.P.);
Department of Pathology, Children's Mercy Hospital, Kansas City, Missouri,
U.S.A. (E.M.T.); and Department of Pathology, Stanford University Medical
Center, Palo Alto, California, U.S.A. (S.A.M.).
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Am J Surg Pathol 2000;24:1239-1246 Abstract quote
The perivascular epithelioid cell family of tumors (PEComas), defined
by their co-expression of melanocytic and muscle markers, includes angiomyolipoma,
lymphangioleiomyoma, and clear cell ``sugar'' tumors of the lung, pancreas,
and uterus.
We present seven cases of a unique and previously unrecognized tumor
of children and young adults, which represents a new addition to the
PEComa group of tumors.
Culled from three institutions over a 50-year period, all cases occurred
in or immediately adjacent to the ligamentum teres and falciform ligament.
Six patients were female and one male; their ages ranged from 3 to 21
years (median, 11 yrs). Tumor sizes ranged from 5 to 20 cm (median,
8 cm). All cases consisted of clear to faintly eosinophilic spindled
cells arranged in fascicular and nested patterns. The cells had small
but distinct nucleoli and low mitotic activity. Immunohistochemically,
all cases were positive with antibodies to gp100 protein (HMB-45) and
negative for S-100 protein. In three of the seven cases studied immunohistochemically,
the tumors expressed smooth muscle actin, melan-A, microphthalmia transcription
factor (MiTF), and myosin, but not desmin. No expression of the TSC2
gene product, tuberin, was seen in three cases. One case studied cytogenetically
disclosed a t(3;10). Follow-up data, available in six of seven cases
(median duration, 18 mos), showed five patients to be free of disease
and one to have a radiographically presumed lung metastasis.
We think these tumors comprise a new entity for which we propose the
term ``clear cell myomelanocytic tumor of the falciform ligament/ligamentum
teres.'' The differential diagnosis of these tumors includes clear cell
sarcoma of tendons and aponeuroses, leiomyosarcoma, and angiomyolipoma.
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HMB-45/Melan-A and Smooth Muscle Actin-Positive Clear-Cell Epithelioid
Tumor Arising in the Ligamentum Teres Hepatis Additional Example of
Clear Cell `Sugar' Tumors
Yukichi Tanaka, M.D.; Rieko Ijiri, M.D.; Keisuke Kato, M.D.; Yoshikazu
Kato, M.D.; Kazuaki Misugi, M.D.; Yukio Nakatani, M.D.; Masamichi Hara,
M.D. Okuda K, Peter RL, eds.
From the Division of Pathology, Kanagawa Childeren's Medical Center
(Y.T., R.I., K.K., Y.K., K.M., Y.N., M.H.), Division of Anatomic and
Surgical Pathology, Yokohama City University Hospital (Y.N.), and the
Department of Clinical Pathology of Yokohama City University Urafune
Hospital, Yokohama, Japan (M.H.).
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Am J Surg Pathol 2000;24:1295-1299 Abstract quote
HMB-45-positive clear-cell epithelioid tumor arising in the ligamentum
teres hepatis of a 13-year-old Japanese girl is described.
The well-defined tumor was completely removed and measured 9 × 7 ×
6 cm. Cut sections showed a tan–white, homogeneous appearances with
no hemorrhage or necrosis. The tumor was composed of nests or sheets
of polygonal or oval-shaped cells rich in clear or finely granular cytoplasm.
Capillary network was well developed, and sinusoid vessels were often
seen with occasional perivascular hyalinization. There was moderate
nuclear atypia but mitotic figures were absent. Periodic acid-Schiff
stain showed a large amount of glycogen digested by diastase. Immunohistochemical
stains for smooth muscle actin, Melan-A, and HMB-45 were positive in
most of the tumor cells. Stains for vimentin, muscle actin, and HAM56
were focally positive, whereas stains for desmin, cytokeratin, epithelial
membrane antigen, S-100, CD34, CD68, CD99, neurofilament proteins, and
estrogen/progesterone receptors were negative. Ultrastructurally, the
cytoplasm contained a considerable number of mitochondria, monoparticipate
or membrane-bound glycogen, and longitudinally oriented thin filaments
with focal condensations and subplasmalemmal densities. The histopathology
of the present case, originally interpreted as epithelioid leiomyoma,
was consistent with clear cell ``sugar'' tumors.
The present case may indicate ubiquitous distribution of clear cell
``sugar tumors'' of which histogenesis remains unknown but is presumed
to be of perivascular epithelioid cell origin.
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