This rare and recently described tumor arises from the falciform ligament or ligamentum teres of children and young adults. Less than 10 cases have been described. These tumors present with abdominal pain, abdominal mass, or both. The vast majority of the cases occurred in the ligamentum teres/falciform ligament and one arose within the omentum.
These tumors form part of a category of tumors known as perivascular epithelioid cell (PEC) tumors, or PEComa. Other names for these tumors include sugar tumors because of the characteristic clear cytoplasmic appearance of these tumors. The following tumors that have classically been included:
Sugar cell tumors of the lung
Clear cell tumors of the pancreas
Clear cell tumors of the uterus
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EPIDEMIOLOGY CHARACTERIZATION SYNONYMS
Clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres
Clear cell sugar tumor of ligamentum teres hepatis
INCIDENCE Very rare AGE RANGE-MEDIAN Median 11 years
Range 3-21 years
SEX (M:F) 6 Female 1 male
PATHOGENESIS CHARACTERIZATION Perivascular epithelioid cell family of tumors (PEComas) Chromosomal translocation One case showed a t(3;10)
GROSS APPEARANCE/CLINICAL VARIANTS CHARACTERIZATION General
Size from 5-20 cm
Median 8 cm
Firm tan-gray masses with focal areas of hemorrhage and cystic change
Clear cell myomelanocytic tumor of the urinary bladder.
Pan CC, Yu IT, Yang AH, Chiang H
Am J Surg Pathol 2003 May;27(5):689-92 Abstract quote
Clear cell myomelanocytic tumors are a recently described neoplastic growth considered to be a member of the family of perivascular epithelioid cell tumor. These tumors have a predilection for falciform ligament/ligamentum teres.
We report an additional case arising from the muscularis propria of the urinary bladder in a 33-year-old woman. The tumor consisted of clear to eosinophilic, epithelioid, and spindled cells arranged in fascicles or packets. A delicate vascular stroma was found among the nests. Immunohistochemically, the tumor cells were typically positive for HMB-45 and smooth muscle actin but negative for S-100 protein, Melan-A, desmin, and pan-cytokeratin. The patient has been free of the disease since the excision of the tumor 6 years ago.
This case, in association with the expanding list of perivascular epithelioid cell tumor reported in different sites, suggests that this type of neoplasm may be ubiquitous.
HISTOLOGICAL TYPES CHARACTERIZATION General
Infiltrative pattern at periphery
Clear to faintly eosinophilic spindled cells arranged in fascicular and nested patterns
Elaborate vasculature with large and small vessels
Small cells with distinct nucleoli
Low mitotic activity <1 MF/20 hpf
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.).
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.
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.).
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.
SPECIAL STAINS/IMMUNOPEROXIDASE/OTHER CHARACTERIZATION HMB45 All positive S-100 All negative Melan-A 3/7 positive Smooth muscle actin 3/7 positive
PROGNOSIS AND TREATMENT CHARACTERIZATION 5 Year Survival 5/6 alive and free of disease after median followup of 18 months Metastasis 1/6 with presumed lung metastases Treatment Surgical removal
Am J Surg Pathol 2000;24:1239-1246.
Am J Surg Pathol 2000;24:1295-1299.
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