CASE 18714 Published on 01.10.2024
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Metastatic TFE3-mutated mesenteric perivascular epithelioid cell tumour (PEComa)

Section

Abdominal imaging

Case Type

Clinical Case

Authors

Marlon Vasquez-Burbano 1, Ana Coma Muñoz 2, Marta Garrido Pontnou 3, Paula Pérez-Albert 2, Élida Vázquez Fernández 2

1 Hospital Universitario San Pedro, Logroño, La Rioja, Spain

2 Pediatric Radiology Department, Hospital Universitario Vall d’Hebron, Barcelona, Catalonia, Spain

3 Pathological Anatomy Department, Hospital Universitario Vall d’Hebron, Barcelona, Catalonia, Spain

4 Oncology Department, Hospital Universitario Vall d’Hebron, Barcelona, Catalonia, Spain

Connected authors
Patient

16 years, female

Categories
Area of Interest Abdomen, Mesentery, Paediatric ; Imaging Technique Catheter arteriography, CT, MR, PET-CT, Ultrasound
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Clinical History

A 16-year-old girl presents with nonspecific and insidious abdominal symptoms such as discomfort, abdominal pain, and distention. The patient came to the emergency room due to pain in the right hemiabdomen. An ultrasound (US) and Computed Tomography (CT) were performed, depicting a central abdominal mass. She was subsequently referred to our hospital for further evaluation. All tumour markers were negative. Lactate dehydrogenase was elevated (621 UI/L, NV 120–246) without any lysis syndrome biochemical alterations.

Imaging Findings

The US showed a large, hypoechogenic, well-defined, heterogeneous mass in the centre of the upper abdomen. No evident Doppler signal was observed within the tumour, but prominent vascular structures were seen around it. It also depicted splenomegaly (Figures 1a, 1b and 1c).

The initial contrast-enhanced CT revealed a large intraabdominal polylobulated mass with central hypodense areas of necrosis/cystic degeneration, peripheral solid-enhancing areas, and the presence of aberrant vascularity (Figures 2a, 2b, 2c and 2d). Multiple metastatic implants were found in the peritoneum, mesentery (Figures 2e and 2f), and liver (Figure 2a).

MRI demonstrated a heterogeneous mass, predominantly hypointense in T1W (not shown), and hyperintense in T2W, with marked diffusion restriction, low ADC values, and evident heterogeneous contrast enhancement (Figures 3a, 3b, 3c and 3d).

Due to the patient’s anaemia and abdominal pain, an urgent digital subtraction angiography (DSA) was performed (Figures 4a and 4b), which showed no bleeding.

Also, a staging PET-CT (Figures 6a and 6b) was performed, and it showed high FDG uptake in both the tumour and the metastasis. The tumour biopsy (Figure 5) stated the diagnosis.

After two years of various chemotherapy treatments, follow-up CT showed slight tumour growth; however, the necrotic/cystic centre had become more pronounced. Additionally, several new metastatic implants were observed in the mesentery, liver, and retroperitoneal lymph nodes (Figures 7a and 7b).

Discussion

Background

Perivascular epithelioid cell tumour (PEC) is a rare mesenchymal neoplasm that includes lymphangioleiomyomatosis, angiomyolipoma, clear cell “sugar” tumour, and other mesenchymal tumours that can arise from any location; Mesenteric PECs are extremely rare, and only a few cases have been described [1–3]. Usually, these tumours can exhibit distinct perivascular epithelioid and spindle cell morphology that express melanocytic and myogenic markers [2–4], and HMB45 is considered the most sensitive melanocytic marker in PEComas [2].

The TFE3 gene is located on Xp11.2, and its translocation often leads to upregulation of TFE3 and subsequent cell proliferation and oncogenesis.

Clinical Perspective

The aetiology of PECs remains unclear [2]. Patients are usually asymptomatic, and eventually, a mass might be detected accidentally during a physical examination or through imaging tests [4]. When symptoms do occur, they are usually nonspecific and include abdominal discomfort, nausea, weight loss, or abdominal pain. Symptoms often relate to the organ or location of the PECs, frequently resulting from a compressive effect [2].

Imaging Perspective

It is important to note that the imaging findings are non-specific. Due to the rarity of these tumours, anatomopathological diagnosis is almost always required [1–5].

In scans, PECs appear as well-defined, hypodense, polylobulated masses of variable size. In non-contrast CT scans, they are usually homogeneous masses. In non-contrast MRI, they tend to be hypointense in T1W and heterogeneously hyperintense in T2W compared to skeletal muscle. Solid areas usually show diffusion restriction. Some types of PECs, such as angiomyolipoma, contain fat [2,5].

PECs usually show heterogeneous arterial and venous enhancement with or without areas of necrosis or cystic degeneration [2,4,5]. Homogeneous enhancement is also described [5].

Calcifications are uncommon with few references to renal PECs [5].

The most frequent sites of metastasis are the lung, liver, and retroperitoneum [5].

Outcome

All gastrointestinal PECs have malignant potential, and close follow-up with imaging is required [2,4].

Due to their rarity, there is no well-established optimal treatment currently. Surgical resection, aiming for complete removal, is the initial choice. Chemotherapy and immunotherapy are treatment options, especially in initially non-resectable cases [2–4].

PEComas are known to harbour TSC2 mutations. A minority of PEComas contain TFE3 gene rearrangements. Also, TFE3 immunoreactivity has been described in younger patients, predominantly women [3], as observed in our case.

Our patient is currently in a Temozolomide and CDK4/6 inhibitors clinical trial.

Teaching Points

  • PECs are usually benign, but malignancy or malignant behaviour is common.
  • Close follow-up with imaging is essential.
  • TFE3-expressing or mutated mesenteric PEComa is rare and more frequent in young women.
  • Imaging findings are nonspecific, and a biopsy is almost always necessary.

All patient data have been completely anonymised throughout the entire manuscript and related files.

Differential Diagnosis List
Metastatic TFE3-expressing mesenteric PEComa
Gastrointestinal stromal tumour (GIST)
Leiomyosarcoma
Clear cell sarcoma
Soft tissue sarcoma
Neuroblastoma
Liposarcoma
Lymphoma
Final Diagnosis
Metastatic TFE3-expressing mesenteric PEComa
Case information
URL: https://eurorad.org/case/18714
DOI: 10.35100/eurorad/case.18714
ISSN: 1563-4086
License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

Abdominal US

Abdominal ultrasound reveals a large intraabdominal, hypoechoic, well-delineated, and heterogeneous mass (arrows). Note the d
Abdominal ultrasound reveals a large intraabdominal, hypoechoic, well-delineated, and heterogeneous mass (arrows). Note the different echogenicity of the mass (*) showing central hypoechogenicity.
Permeable portal vein (arrow) and collateral circulation in the liver hilum (arrowhead), suggesting cavernous transformation of the portal vein.
Permeable portal vein (arrow) and collateral circulation in the liver hilum (arrowhead), suggesting cavernous transformation of the portal vein.
Homogeneous splenomegaly due to compression of the splenic-portal axis.
Homogeneous splenomegaly due to compression of the splenic-portal axis.
Figure 2

Contrast-enhanced CT

Axial abdominal contrast-enhanced CT. Suspicious macroscopic calcifications are visible in the right hepatic lobule (arrow). The main abdominal mass is partially included in this slice. It corresponds to the upper part of the mass shown in Figure 1a. Note the presence of collateral circulation (yellow arrowhead) and free intraabdominal liquid (*).
Axial abdominal contrast-enhanced CT. Suspicious macroscopic calcifications are visible in the right hepatic lobule (arrow). The main abdominal mass is partially included in this slice. It corresponds to the upper part of the mass shown in Figure 1a. Note the presence of collateral circulation (yellow arrowhead) and free intraabdominal liquid (*).
Axial abdominal contrast-enhanced CT. A large, well-delineated, and polylobulated abdominal mass with central hypodense areas of necrosis/cystic degeneration (*) is surrounded by solid peripheral areas showing vivid contrast enhancement and marked aberrant vascularity. Collateral circulation is also present (yellow arrowhead).
Axial abdominal contrast-enhanced CT. A large, well-delineated, and polylobulated abdominal mass with central hypodense areas of necrosis/cystic degeneration (*) is surrounded by solid peripheral areas showing vivid contrast enhancement and marked aberrant vascularity. Collateral circulation is also present (yellow arrowhead).
Axial abdominal contrast-enhanced CT. A large intraabdominal mass (*) demonstrates the same findings as in 2b, exerting a compressive effect on the splenic-portal venous axis (yellow arrows) and causing collateral circulation. The normal pancreas tail is indicated (P).
Axial abdominal contrast-enhanced CT. A large intraabdominal mass (*) demonstrates the same findings as in 2b, exerting a compressive effect on the splenic-portal venous axis (yellow arrows) and causing collateral circulation. The normal pancreas tail is indicated (P).
Coronal MPR abdominal contrast-enhanced CT. A large intraabdominal mass (*), with the same findings as in Figure 2b. Note the aberrant vascularity (arrowhead) and the fat pad (arrows) between the liver and the mass.
Coronal MPR abdominal contrast-enhanced CT. A large intraabdominal mass (*), with the same findings as in Figure 2b. Note the aberrant vascularity (arrowhead) and the fat pad (arrows) between the liver and the mass.
Axial abdominal contrast-enhanced CT. A large intraabdominal mass (*) with similar findings as in Figure 2b, and a well-defined hypodense implant in the mesentery (white arrow). Collateral circulation is again noted (yellow arrow). Note that in the sequence of images 1a-1d, the mass does not appear to be dependent on the kidneys, adrenal glands, liver, stomach, or pancreas.
Axial abdominal contrast-enhanced CT. A large intraabdominal mass (*) with similar findings as in Figure 2b, and a well-defined hypodense implant in the mesentery (white arrow). Collateral circulation is again noted (yellow arrow). Note that in the sequence of images 1a-1d, the mass does not appear to be dependent on the kidneys, adrenal glands, liver, stomach, or pancreas.
Axial pelvis contrast-enhanced CT. An enhancing implant is observed in the pelvis (arrowhead). Free pelvic fluid is noted (*). The bladder (B) and uterus (arrow) are shown.
Axial pelvis contrast-enhanced CT. An enhancing implant is observed in the pelvis (arrowhead). Free pelvic fluid is noted (*). The bladder (B) and uterus (arrow) are shown.
Figure 3

MRI

Axial T2-weighted image. Heterogeneous well-delimitated and polylobulated intraabdominal mass (*) with central hyperintense areas of necrosis/cystic degeneration is seen. Compared to Figure 2b, the mass has changed its position from the left to the right side, suggesting that it is related to an organ with wide mobility, such as the mesentery.
Axial T2-weighted image. Heterogeneous well-delimitated and polylobulated intraabdominal mass (*) with central hyperintense areas of necrosis/cystic degeneration is seen. Compared to Figure 2b, the mass has changed its position from the left to the right side, suggesting that it is related to an organ with wide mobility, such as the mesentery.
Coronal T2-weighted image. Heterogeneous well-delimitated and polylobulated intraabdominal mass with similar findings in Figure 3a.
Coronal T2-weighted image. Heterogeneous well-delimitated and polylobulated intraabdominal mass with similar findings in Figure 3a.
Axial T2-weighted image. The main intraabdominal mass (*) and a mesentery implant (arrow) with findings similar to Figure 3a are shown. The pancreas tail (P) is visible.
Axial T2-weighted image. The main intraabdominal mass (*) and a mesentery implant (arrow) with findings similar to Figure 3a are shown. The pancreas tail (P) is visible.
Axial diffusion-weighted image and its ADC map. Solid areas of the tumour show intense diffusion restriction with low ADC values.
Axial diffusion-weighted image and its ADC map. Solid areas of the tumour show intense diffusion restriction with low ADC values.
Figure 4

Digital subtraction angiography

Digital subtraction angiography: arterial phase. Arteriography of the celiac trunk showed aberrant vascularity (arrows) of the intraabdominal mass and did not demonstrate any active bleeding. The splenic artery (S), hepatic artery (H), and left gastric artery (G) are shown.
Digital subtraction angiography: arterial phase. Arteriography of the celiac trunk showed aberrant vascularity (arrows) of the intraabdominal mass and did not demonstrate any active bleeding. The splenic artery (S), hepatic artery (H), and left gastric artery (G) are shown.
Digital subtraction angiography: venous phase. The study reveals venous vascularisation in the solid areas of the tumour (*) and hypovascularisation in the central areas (+). Collateral circulation is noted again (arrows).
Digital subtraction angiography: venous phase. The study reveals venous vascularisation in the solid areas of the tumour (*) and hypovascularisation in the central areas (+). Collateral circulation is noted again (arrows).
Figure 5

Pathological examination

40x Hematoxylin-eosin. Pathological examination showed epithelioid tumour forming clusters (*) separated by fine vascular structures (arrows). The cells have large, granular, eosinophilic cytoplasm with round nuclei and very prominent nucleoli.
40x Hematoxylin-eosin. Pathological examination showed epithelioid tumour forming clusters (*) separated by fine vascular structures (arrows). The cells have large, granular, eosinophilic cytoplasm with round nuclei and very prominent nucleoli.
Figure 6

FDG-PET-CT fused images

FDG-PET-CT fused image. Axial and MPR sagittal and coronal images. Intense FDG uptake of the mass is observed in the peripheral solid areas.
FDG-PET-CT fused image. Axial and MPR sagittal and coronal images. Intense FDG uptake of the mass is observed in the peripheral solid areas.
Axial FDG-PET-CT fused image. Intense FDG uptake of the main intraabdominal metastasis is noted.
Axial FDG-PET-CT fused image. Intense FDG uptake of the main intraabdominal metastasis is noted.
Figure 7

Two years follow-up

Two years follow-up axial contrast-enhanced CT. The suspicious macroscopic calcifications in the right hepatic lobule shown in Figure 2a were metastasis (arrow). New metastatic implants (*).
Two years follow-up axial contrast-enhanced CT. The suspicious macroscopic calcifications in the right hepatic lobule shown in Figure 2a were metastasis (arrow). New metastatic implants (*).
Coronal MPR and axial CT at different levels. New metastatic implants on the peritoneum, mesentery, new liver metastasis (arrowheads), and retroperitoneal adenopathies (yellow arrowheads). The main tumour (*) and the pelvic implant in Figure 2f show an important growth.
Coronal MPR and axial CT at different levels. New metastatic implants on the peritoneum, mesentery, new liver metastasis (arrowheads), and retroperitoneal adenopathies (yellow arrowheads). The main tumour (*) and the pelvic implant in Figure 2f show an important growth.