Clinical Challenges

What is your diagnosis? - April 2019

A 68-year-old woman, asymptomatic, with no medical history, underwent an abdominal computed tomography scan in a traumatic context. An enhanced series (Figure A) revealed a 4-cm cystic mass with tissue and calcified rim components located under the left liver (Figure A, arrow) inside the ligamentum teres. The lesion was supplied by a left hepatic artery branch. The frontal view showed the mass drainage into the left external iliac vein through a long pedicle (the umbilicus vein connected to the left inferior epigastric vein) (v).

A laparoscopic resection of this mass was performed because of the risk of spontaneous hemorrhage linked to the dense tumoral vasculature and the lack of formal histologic diagnosis. During the procedure, the surgeon observed a cystic mass attached to the ligamentum teres between the liver and the umbilicus. At pathologic examination (Figure B), a well-circumscribed largely cystic mass, with a fibrous and calcified shell and hemorrhagic modifications (arrow) was observed.

Histologically (Figure C), the fibrous wall contained many large vessels and a small cellular area (star). This area consisted of small nests of moderate-sized monotonous clear cells with normochromatic ovoid nuclei. There was no nuclear atypia and no mitosis. The tumor exhibited an elaborate network of small capillaries. Tumor cells expressed the melanocytic marker HMB45 and smooth muscular actin.


 

Cystic and calcified PEComa of the ligamentum teres

PEComas are tumors derived from epithelioid perivascular cells that typically coexpress smooth muscle and melanocytic markers. The family of PEComas includes angiomyolipoma, clear cell “sugar” tumor, and lymphangioleiomyomatosis. Some of these tumors may be associated with tuberous sclerosis complex. PEComas of the ligamentum teres (also called in this location “clear cell myomelanocytic tumors”) are rare, but the ligamentum teres location is the most classic in children. Thirteen cases have been reported in the literature, within or in the immediate vicinity of falciform ligament/ligamentum teres.1-3 There was a marked female predominance with a mean age of 20 years (range, 3-54 years), a mean size of 8 cm (range, 5-20 cm), and a significant risk of metastasis (3 of 13 cases). Many of the lesions were calcified and had hemorrhagic and cystic alterations.

In the absence of established malignancy criteria, PEComas must be considered to have an uncertain malignant potential, requiring surgical resection and long-term monitoring. A mass of the ligamentum teres should always lead to consideration of the diagnosis of PEComa, even in adults, and even with cystic presentation. Moreover, most frequently, other tumors of the ligamentum teres are malignant (local extension of hepatocellular carcinoma, metastatic adenocarcinoma of gastrointestinal or gynecological origin). The patient was free of disease at 6 months’ follow-up.

References

1. Folpe AL, Goodman ZD, Ishak KG, et al. 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. Am J Surg Pathol. 2000;24:1239-46.

2. Folpe AL, Mentzel T, Lehr HA, et al. Perivascular epithelioid cell neoplasms of soft tissue and gynecologic origin. Am J Surg Pathol. 2005;29:1558-75.

3. Alaggio R, Cecchetto G, Martignoni G, et al. Malignant perivascular epithelioid cell tumor in children: description of a case and review of literature. J Pediatr Surg. 2012;47:31-40.

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