Pericardial Perivascular Epithelioid Cell Neoplasm

Abstract

Supplemental material is available for this article.

An echocardiogram obtained in an asymptomatic 31-year-old man undergoing hypertension evaluation revealed normal function (left ventricular ejection fraction 60%), pericardial effusion, and a pericardial mass. Cine imaging (Figure, A and B; Movie [supplement]) at subsequent cardiac MRI showed a well-circumscribed, heterogeneous mass adjacent to the left atrioventricular groove that moved within the pericardial space independently of the parietal pericardial surface, but which appeared inseparable from the left atrium, suggesting that this mass arose from the visceral pericardium. The mass enhanced heterogeneously at contrast-enhanced MR angiography but only demonstrated some patchy areas of enhancement on late gadolinium-enhanced images (Figure, C and D, respectively). Chest CT showed coarse calcifications detected within the mass (Figure, E), which narrowed the differential diagnosis to pericardial masses containing calcification: germ cell tumor (teratoma), fibroma, hemangioma, and pericardial perivascular epithelioid cell neoplasm (PEComa) (1–5). A lack of avid enhancement on late gadolinium enhancement images made pericardial fibroma unlikely (4). Decreased enhancement over time made pericardial hemangioma less likely. Metastatic disease was excluded by thorough clinical investigation.

Figure:

Images in an asymptomatic 31-year-old man undergoing hypertension evaluation. A, B, Two-chamber and short-axis cardiac MR cine images show a well-circumscribed, heterogeneous mass (arrows) adjacent to the left atrioventricular groove and within the pericardial space. C, Contrast-enhanced MR angiogram shows that the mass (arrow) enhanced heterogeneously. D, Late gadolinium-enhanced image shows patchy areas of enhancement within the mass (arrow). E, Noncontrast chest CT image shows coarse calcifications within the mass (arrow). F, Intraoperative image shows the mass (arrow) within the pericardial space adjacent to the left atrium and anterior to the left atrial appendage (*).

Movie:

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Two-chamber cine movie shows a large, well-demarcated, heterogeneous mass within the pericardial space. A large pericardial effusion is also present. The mass moves independently relative to the parietal pericardial surface. However, the mass appears inseparable from the left atrium, suggesting that it arises from the visceral pericardial surface.

Surgical resection confirmed that the mass was located within the pericardial space adjacent to the left atrium and anterior to the left atrial appendage (Figure, F). Histologic analysis of the mass with hematoxylin-eosin stain showed spindle cells with hollow cytoplasm and stromal calcification. Subsequent immunohistochemical tissue evaluation (HMB45 stain) resulted in the diagnosis of PEComa (1–3). Pericardial masses are uncommon and usually secondary to metastases. Primary tumors of the pericardium include mesothelioma, germ cell tumor, various sarcomas, lymphoma, fibroma, hemangioma, and PEComa (3,4). Pericardial PEComa is associated with tuberous sclerosis, and its discovery warrants genetic evaluation as well as additional imaging to assess for additional manifestations of tuberous sclerosis (1). The PEComa family includes lymphangioleiomyomatosis, angiomyolipoma, clear cell “sugar” tumor of the lung, as well as additional morphologically and immunophenotypically similar tumors that can arise throughout the body (1,3).