Open Access

Perivascular epithelial cell tumor (PEComa) of the pancreas: a case report and review of previous literatures

  • Yusuke Mizuuchi1Email author,
  • Kazuyoshi Nishihara1,
  • Akifumi Hayashi3,
  • Sadafumi Tamiya2,
  • Satoshi Toyoshima2,
  • Yoshinao Oda4 and
  • Toru Nakano1
Surgical Case Reports20162:59

https://doi.org/10.1186/s40792-016-0186-x

Received: 5 February 2016

Accepted: 9 June 2016

Published: 15 June 2016

Abstract

Perivascular epithelial cell tumors (PEComas), firstly described by Bonetti in 1992, are a family of mesenchymal tumor composed of perivascular epithelioid cells having epithelioid or spindle morphology and exhibiting melanocytic and myogenic immunoreactivities. We herein described a 61-year-old woman who presented with epigastric pain. Preoperative imaging studies showed that 7-cm-sized mass was located in pancreatic head and body, and pancreaticoduodenectomy was performed. Histological findings showed that the tumor was composed of clear epithelioid cells with abundant glycogen granules, which grew in a nested and alveolar pattern around blood vessels. The tumor cells showed immunoreactivities for HMB-45 but did not express epithelial or endocrine markers. These histological features indicated those of PEComa. This report underlines that we should recognize PEComa as a preoperative differential diagnosis of pancreatic tumors.

Keywords

Perivascular epithelioid cell tumorPancreatic neoplasmHMB-45Alpha-smooth muscle actin

Background

Perivascular epithelial cell tumors (PEComas) are a family of mesenchymal tumors composed of perivascular epithelioid cells having epithelioid or spindle shape, clear to granular cytoplasm, centrally located, round to oval nucleus and inconspicuous nucleoli. Immunohistochemically, these neoplastic cells exhibit melanocytic marker, HMB-45, and occasionally myogenic marker, α-SMA. Angiomyolipoma, lymphangioleiomyoma, and clear cell “sugar” tumor are included in the PEComa family. PEComas arise in various organs throughout the body, especially in soft tissue, bone, abdominopelvic sites, or retroperitoneal site such as the kidney, uterus, and gastrointestinal tract, but PEComa arising in pancreas is extremely rare. We described a primary PEComa occurring in the pancreatic body of a 61-year-old woman without a history of tuberous sclerosis complexes.

Case presentation

A 61-year-old woman was referred to our hospital with epigastralgia. Abdominal ultrasonographic examination showed 7-cm-sized mass in the head and body of the pancreas. Physical examination was unremarkable, and any symptoms were not presented except for mild epigastric tenderness. She had smoked one pack of cigarettes per day for 32 years until quitting smoking 8 years before, but not had a history of tuberous sclerosis complexes, malignancy, habitual alcohol consumption, or diabetes mellitus.

The results of blood tests were shown in Table 1. The serum levels of tumor markers showed no significant abnormal findings. As for endocrinology, serum gastrin and somatostatin levels were slightly elevated, but negative results were obtained for serum glucagon, vasoactive intestinal peptide (VIP), serotonin, and plasma immunoreactive insulin (IRI).
Table 1

Laboratory data

•Hematology

•Tumor marker

 WBC

4600/mm3

 CEA

0.7 ng/ml

 RBC

349 × 104/mm3

 CA19-9

7.7 U/ml

 Hb

9.9 g/dl

 AFP

1.6 ng/ml

 Ht

23.20 %

 Elastase 1

173 ng/dl

 Plt

23.2 × 104 /mm3

 SPAN-1

11 U/ml

 

 DUPAN-2

<25 U/ml

•Blood chemistry

 TP

7.9 g/dl

•Endocrinology

 

 Alb

4.3 g/dl

 Gastrin (<200)

370 pg/ml

 T.Bil

0.7 mg/dl

 Glucagon (40~180)

81 pg/ml

 AST

27 IU/L

 IRI (0~16)

7.8 μU/ml

 ALT

15 IU/L

 VIP (<100)

11 pg ml

 LDH

265 IU/L

 Serotonin (40~350)

47 ng/ml

 ALP

220 IU/L

 Somatostatin (1.0~12)

23 pg/ml

 ɤ-GTP

12 IU/L

  

 Glucose

94 mg/dl

•Serology

 

 BUN

7.3 mg/dl

 CRP

0.2 mg/dl

 Cr

0.6 mg/dl

  

 Na

141 mEq/L

  

 K

4.3 mEq/L

  

 Cl

106 mEq/L

  
Abdominal ultrasonographic examination showed that gourd-shaped hypo- and iso-echoic mass, 56 mm in size, was detected in the pancreatic head and body (Fig. 1a). Upstream main pancreatic duct was slightly dilated, 5 mm in diameter, by extrinsic compression of the mass. Neither dilatation of common bile duct nor large vessel involvement was observed.
Fig. 1

Imaging studies. a Ultrasonography showed that gourd-shaped hypo- and iso-echoic mass, 56 mm in size, was detected in the pancreatic head and body. b Enhanced computer tomography showed that solid well-circumscribed low-density mass, 7 cm in diameter, was located in the pancreatic head and body. c Heterogeneously enhanced mass was detected in the pancreatic body by gadolinium-enhanced MRI. d Endoscopic retrograde pancreatography (ERP) showed that main pancreatic duct was slightly deviated downward because of locoregional pressure effect, but direct invasion to the main pancreatic duct was not evident

Abdominal enhanced computed tomography (CT) scans revealed that a solid low-density mass approximately 7 cm in diameter, which was circumferentially well-demarcated, was located in the pancreatic body (Fig. 1b). The tumor was shown to be derived from the parenchyma of the pancreas. Upstream dilatation of main pancreatic duct was also noted. Neither evidences of distant metastasis nor direct invasion to adjacent organs were detected. In addition, CT scan showed that enlarged lymph nodes were not detected throughout the body including in peri-pancreatic region.

Magnetic resonance imaging (MRI) showed that the solid round mass had heterogeneous signal intensity on a T1- and T2-weighted image. In addition, gadolinium-enhanced MRI revealed that the mass was heterogeneously enhanced in the pancreatic body (Fig. 1c).

Endoscopic retrograde pancreatography (ERP) showed that main pancreatic duct was slightly deviated downward because of locoregional pressure effect, but direct invasion to the main pancreatic duct was not evident (Fig. 1d).

Neuroendocrine neoplasms, acinar cell carcinoma, and ductal adenocarcinoma variants such as clear cell carcinoma, or solid-pseudopapillary neoplasm, were suggested before operation. Since malignant tumor could not be denied according to the preoperative imaging studies, she underwent pancreaticoduodenectomy to establish a definitive diagnosis.

Macroscopically resected specimen showed a well-circumscribed vaguely lobulated mass, 6 cm in diameter, distributed mainly in the ventral side of the pancreatic head and body (Fig. 2a). The cut surface of the resected specimen revealed the brownish-colored encapsulated solid mass associated with hemorrhage at the body of the pancreas (Fig. 2b). Neither pancreatic duct change (stenosis, dilatation) nor common bile duct dilatation was evident in these specimens.
Fig. 2

Macro- and microscopic findings of the resected specimens. a Well-circumscribed vaguely lobulated mass distributed mainly in the ventral side of the pancreatic head and body. b The cut surface of the resected specimen revealed that the brownish-colored encapsulated mass was solid associated with hemorrhage and contiguous to the pancreas. c, d Histological findings showed that the tumors were composed of perivascularly arranged epithelioid tumor cells possessing clear to focally granular eosinophilic cytoplasm, round to oval nucleus and inconspicuous nucleoli, diffusely proliferated in solid nests or alveolar pattern with sinusoidal vasculatures (hematoxylin and eosin stain C ×100, D ×400)

Microscopically, the tumors were composed of epithelioid tumor cells possessing clear to focally granular eosinophilic cytoplasm, centrally located, round to oval nucleus and inconspicuous nucleoli, diffusely proliferated in solid nests or alveolar pattern with sinusoidal vasculatures. Neither necrosis, calcification, lipomatous component, infiltrative growth pattern, mitotic figures nor vessels permeation was evident. The tumor was sharply demarcated from the pancreatic parenchyma by thick fibrous tissue (Fig. 2c, d). Results of immunohistochemical and special stain were summarized in Table 2. The tumor cells had cytoplasmic periodic acid-Schiff positive granules, which were completely digested by diastase, indicating these granules as glycogen. Immunohistochemically, these tumor cells are positive for neuron-specific enolase (NSE) and human melanoma black 45 (HMB-45), but negative for myogenic markers (α-smooth muscle actin (α-SMA) and HHF-35), epithelial markers (AE1/AE3, CAM5.2), endocrine markers (synaptophysin, chromogranin A), and acinar markers (trypsin and α-1-antitrypsin) (Fig. 3). These morphological and immunohistochemical features indicate PEComa. Ki-67 labeling index was less than 1 %.
Table 2

Results of immunohistochemical stain

Positive

Negative

PAS

PAS with diastase digestion

Fontana-Masson

Cytokeratins (CAM5.2, AE1/AE3)

HMB-45

Epithelial membrane antigen (EMA)

Neuron-specific enolase (NSE)

a-smooth muscle actin (a-SMA)

 

Chromogranin A

 

Synaptophysin

 

a-1-antitrypsin

 

S-100

 

Vimentin

 

HHF-35

 

Gastrin

 

Somatostatin

Fig. 3

Immunohistochemical analyses. a, b The tumor cells (arrow) revealed cytoplasmic immunoreactivities for melanocytic marker, HMB-45, but negative for epithelial marker, CAM5.2. In normal pancreatic tissue (asterisk), CAM5.2 was diffusely positive, but very confined immunoreactivity was shown for HMB-45. c, d The tumor cells are negative for S-100 and α-smooth muscle actin (α-SMA). Sinusoidal vasculatures were positive for α-SMA

The postoperative course was uneventful, and she discharged 18 days after surgical operation without impaired glucose tolerance. The patient is doing well and free of recurrence 12 years after surgical resection.

Discussion

PEComa is a term that WHO defined as “a mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells (PECs)” [1]. The PECs are characterized by epithelioid or spindle-shaped appearance with a clear, eosinophilic, or granular cytoplasm, a round to oval, centrally located nucleus and an inconspicuous nucleolus. Immunohistochemical stain shows that the tumor cells are positive for HMB-45 and occasionally positive for α-SMA, S-100, and desmin, but negative for cytokeratins and endocrine markers [2]. Diffuse immunoreactivities for HMB-45 confirm that the tumor cells have melanocytic features.

By morphological and immunohistochemical similarity, PEComa family encompasses angiomyolipoma, lymphangioleiomyoma, and clear cell “sugar” tumor [3]. PEComa arise in various organs throughout the body, especially in soft tissue, bone, abdominopelvic sites, or retroperitoneal site such as the kidney, uterus, and gastrointestinal tract, but PEComa arising in pancreas is extremely rare [4]. Since Zamboni et al. firstly reported pancreatic clear cell “sugar” tumor in 1996 [5], 14 reports of this tumor family arising in pancreas were documented including this report [517]. Previously reported pancreatic PEComas were summarized in Table 3. The patient group consisted of 12 women and 2 men, indicating female predominance. In addition, these tumors can arise in any age of patients (age range from 17 to 74; mean age of 49.4 years) but typically found in middle-aged to elderly women. Tumors were located in pancreatic head in six patients, in pancreatic body in six patients, and in uncinated process in two patients, indicating that this tumor family could arise anywhere in the pancreas. The mean tumor size was 3.9 cm (range from 1.5 to 10 cm). Primary symptoms included abdominal pain in nine patients, diarrhea, melena, fever, and bulge in stomach in one patient, respectively. Ultrasonography for follow-up of hepatic hemangioma revealed pancreatic head mass in one patient without chief complaint [13].
Table 3

Summary of previous reports of pancreatic PEComa

Author

Year

Age

Sex

Tuberous sclerosis

Symptoms

Location

Operative procedure

Size (cm)

Histology

Morphological features

Zamboni

1996

60

F

-

abdominal pain

body

DP

2

clear cell sugar tumor

epithelioid

Heywood

2004

74

F

-

abdominal pain

uncinate process

PPPD

4.7

angiomyolipoma

epithelioid

Ramuz

2005

31

F

-

abdominal pain

body

SPDP

1.5

sugar tumor

epithelioid

Perigny

2008

46

F

N.A

diarrhea

body

Enucleation

1.7

PEComa

spindle > epithelioid

Hirabayashi

2009

47

F

-

abdominal pain

head

PPPD

1.7

PEComa

spindle

Baez

2009

60

F

-

abdominal bulge

body

DP

3.5

PEComa (sugar tumor)

epithelioid + spindle

Zemet

2011

49

M

-

fever, cough and malaise

head

PPPD

4

PEComa

epithelioid smooth muscle cells

Nagata

2011

52

M

-

abdominal pain

head

PD

4

PEComa

epithelioid

Finzi

2012

62

F

-

none

head

Total excision

2.5

PEComa

epithelioid

Al-Haddad

2013

38

F

N.A

abdominal pain

uncinate process

PD

1.8

PEComa

epithelioid + spindle

Okuwaki

2013

43

F

-

abdominal pain

body and tail

DP

10

PEComa

spindle

Mourra

2013

51

F

-

abdominal pain, jaund:

head

PD

6

malignant PEComa

epithelioid

Petrides

2015

17

F

N.A

melena, anemia

head

PPPD

4.2

PEComa

epithelioid + spindle

Our patient

2015

61

F

-

abdominal pain

body

PD

7

PEComa

epithelioid

Glycogen granules

Necrosis

Mitosis

Ki-67 LI

Hemorrhage

α-SMA

HMB45

S-100

Desmin

Endocrine markers

Cytokeratins

Recurrence

Follow up

+

N.A

-

<1%

focally +

+

+

focally +

N.A

-

-

-

3 months

N.A

-

N.A

N.A

+

+

+

-

N.A

-

-

-

69 months

+

-

-

<1%

-

focaly +

+

focally +

-

-

-

-

9 months

+

-

1/50HPF

N.A

N.A

+

+

focally +

N.A

N.A

CK1 +

-

3 months

+

-

1/10HPF

<1%

-

+

+

+

-

-

-

-

12 months

+

-

Rare

N.A

N.A

+

+

N.A

+

N.A

-

-

7 months

+

-

-

<1%

N.A

+

+

N.A

N.A

N.A

-

-

10 months

N.A

N.A

1/50HPF

N.A

+

N.A

+

N.A

N.A

N.A

-

Liver

27 months

+

N.A

Rare

8%

N.A

+

+

focally +

N.A

-

-

-

5 months

+

N.A

N.A

N.A

N.A

+

+

-

N.A

-

-

N.A

N.A

N.A

+

N.A

<5%

+

+

+

-

N.A

N.A

-

-

7 months

+

+

2/50HPF

N.A

+

-

+

-

-

N.A

-

Liver

6 months

N.A

N.A

infrequent

N.A

N.A

+

+

-

-

-

-

-

18 months

+

-

-

<1%

+

-

+

-

-

-

-

-

12 years

DP distal pancreatectomy, PPPD pylorus preserving pancreaticoduodenectomy, PD pancreaticoduodenectomy

Histological diagnosis of these tumors was PEComa in ten patients, malignant PEComa in one patient, angiomyolipoma in one patient, and clear cell sugar tumor in two patients. These tumors contained varying proportions of epithelioid cell and spindle-shaped cell components [2] and associated with glycogen granules in nine patients, necrosis in two patients, and hemorrhage in six patients. In our patient, the tumor was composed mostly of epithelioid cells with clear cytoplasm, and spindle-shaped tumor cells are inconspicuous in these specimens. Glycogen granules and hemosiderin deposition are also noted, but tumor necrosis is not observed. Immunohistochemically, all the patients suffering pancreatic PEComa exhibited immunoreactivity for HMB-45 and αSMA except for two patients including our patient. S-100 immunoreactivity was observed in one patient and focally observed in four patients, and the others were negative. Desmin immunoreactivity was observed in one patient, and the others were negative as we could retrieve. Neither endocrine nor epithelial markers exhibited immunoreactivities. Myogenic marker, αSMA, exhibited immunoreactivity in spindle-shaped cells with muscular feature, and smooth muscle actin was found in 80 % of PEComa patients [2, 18]. In the present case, the tumor cells were negative for αSMA, different from other previously reported pancreatic PEComas except for one case, probably since the tumor was composed mostly of epithelioid cells in our patient [4]. Ki-67 labeling index was less than 1 % in large proportion of pancreatic PEComa patients including our patient except for one patient with less than 5 %. Prognosis of pancreatic PEComa is good, most patients remained free of relapse; however, followed-up period was only within 1 year except for the patient for 5 years. Our patient has been no sign of recurrence for 12 years. Thus, our case is the first report of long-term follow-up of PEComa of the pancreas over 10 years.

Differential diagnoses of pancreatic PEComa were included epithelial tumors such as primary clear cell carcinoma, metastatic renal cell carcinoma, endocrine tumor with clear cell change, solid pseudopapillary neoplasm, and acinar cell carcinoma. It is relatively easy to distinguish this entity from the other possible diseases in surgical resected specimen by immunohistochemical study for epithelial markers, neuroendocrine markers, acinar markers, myogenic markers, and HMB-45. Recently, clear cell sarcoma arising in pancreas was reported by Huang et al. [19]. This rare malignant soft tissue neoplasm affects young adult, has a poor prognosis, and expresses melanocytic marker, HMB-45. We could rule out this tumor entity because S-100 protein immunoreactivity was low in the tumor of our patient.

Tuberous sclerosis is a systemic genetic disease that caused seizures, intellectual disability, and benign tumor development in multiple organs including the brain and skin [2, 20, 21]. Recent study mentioned that mTOR inhibitor was effective in PEComa associated with tuberous sclerosis because of mTOR pathway upregulation [22]. Although many lesions of PEComa family observed in tuberous sclerosis complex patients, there are no pancreatic PEComa patients having a history of tuberous sclerosis complexes to the extent that we could retrieve, possibly suggesting that pancreatic PEComa has little association with tuberous sclerosis complexes.

Folpe et al. reported in 2005 that the presence of tumor recurrence or metastasis was predicted by worrisome features in PEComa arising from soft tissue and gynecologic origins [2]. Worrisome features included large size (>5 cm), infiltrative growth, high nuclear grade, hypercellularity, necrosis, and high mitotic figures (>1/50 HPF). Previous reports in pancreatic PEComa revealed liver metastasis in two patients. When we adapted these worrisome features to pancreatic PEComa and retrieved these features as we can from the literatures about these two recurrent tumors, we found necrosis in one patient, and mitotic figures are sparsely seen (2/50HPF and 1/50HPF, respectively), but the other features are lacking in these tumors. In our patient, the tumor is 6 cm in size and mitoses are seen (1/50HPF), thus applicable to two worrisome features of PEComa arising from the soft tissue and gynecologic organs, but our patient is free of recurrence 12 years after surgery.

As pancreatic PEComa is difficult to diagnose preoperatively, extensive resection with lymph nodes dissection such as pancreaticoduodenectomy and distal pancreatectomy was performed in 12 patients including our patients, whereas two patients underwent local excision. Lymph node relapse was not seen in the patients of pancreatic PEComa, suggesting that lymph node dissection might be omitted in pancreatic PEComa.

In our patient, serum levels of gastrin and somatostatin were slightly elevated in contrast to the other reports of PEComa, but the cause of elevating these hormones is not determined in other blood tests and imaging studies. Furthermore, immunohistochemical staining revealed the tumor cells were negative for gastrin or somatostatin.

Since clinical experience of pancreatic PEComa is very limited, the accumulation of this disease’s reports is required to define the worrisome features as an indicator of recurrence and metastasis of pancreatic PEComa, and since the tumor can recur, we recommend complete resection and careful follow-up.

Conclusions

We reported the patient with PEComa arising in pancreatic body with characteristic immunohistological features. We suggest that clinicians should be aware of pancreatic PEComa in diagnosing a patient with pancreatic mass, if there are findings suspicious for neoplasm with clear cell features including clear cell carcinoma, acinar cell carcinoma, or solid pseudopapillary neoplasm in preoperative imaging studies or EUS-guided biopsy samples.

Consent

Written informed consent was obtained from the patient for the publication of this Case Report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Abbreviations

CT, computed tomography; ERP, endoscopic retrograde pancreatography; HMB-45, human melanoma black 45; IRI, immunoreactive insulin; MRI, magnetic resonance imaging; NSE, neuron-specific enolase; PEComas, perivascular epithelial cell tumors; PECs, perivascular epithelioid cells; VIP, vasoactive intestinal peptide; α-SMA, α-smooth muscle actin

Declarations

Acknowledgements

None.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors’ Affiliations

(1)
Department of Surgery, Kitakyushu Municipal Medical Center
(2)
Department of Pathology, Kitakyushu Municipal Medical Center
(3)
Department of Surgery, JR Kyushu Hospital
(4)
Department of Anatomical Pathology, Graduate School of Medical Sciences, Kyushu University

References

  1. Fletcher CD, Bridge JA, Hogendoorn P, Mertens F. WHO classification of tumours of soft tissue and bone. Lyon: International Agency for Research on Cancer; 2013.Google Scholar
  2. Folpe AL, Mentzel T, Lehr HA, Fisher C, Balzer BL, Weiss SW. Perivascular epithelioid cell neoplasms of soft tissue and gynecologic origin: a clinicopathologic study of 26 cases and review of the literature. Am J Surg Pathol. 2005;29:1558–75.View ArticlePubMedGoogle Scholar
  3. Folpe AL, Kwiatkowski DJ. Perivascular epithelioid cell neoplasms: pathology and pathogenesis. Hum Pathol. 2010;41:1–15.View ArticlePubMedGoogle Scholar
  4. Martignoni G, Pea M, Reghellin D, Zamboni G, Bonetti F. PEComas: the past, the present and the future. Virchows Arch. 2008;452:119–32.View ArticlePubMedGoogle Scholar
  5. Zamboni G, Pea M, Martignoni G, Zancanaro C, Faccioli G, Gilioli E, et al. Clear cell “sugar” tumor of the pancreas: a novel member of the family of lesions characterized by the presence of perivascular epithelioid cells. Am J Surg Pathol. 1996;20:722–30.View ArticlePubMedGoogle Scholar
  6. Heywood G, Smyrk TC, Donohue JH. Primary angiomyolipoma of the pancreas. Pancreas. 2004;28:443–5.View ArticlePubMedGoogle Scholar
  7. Ramuz O, Lelong B, Giovannini M, Delpero JR, Rochaix P, Xerri L, et al. Sugar tumor of the pancreas: a rare entity that is diagnosable on preoperative fine-needle biopsies. Virchows Arch. 2005;446:555–9.View ArticlePubMedGoogle Scholar
  8. Périgny M, Larochelle O, Hammel P, Sauvanet A, Dokmak S, Belghiti J, et al. Pancreatic perivascular epithelioid cell tumor (PEComa). Ann Pathol. 2008;28:138–42.View ArticlePubMedGoogle Scholar
  9. Hirabayashi K, Nakamura N, Kajiwara H, Hori S, Kawaguchi Y, Yamashita T, et al. Perivascular epithelioid cell tumor (PEComa) of the pancreas: immunoelectron microscopy and review of the literature. Pathol Int. 2009;59:650–5.View ArticlePubMedGoogle Scholar
  10. Baez JC, Landry JM, Saltzman JR, Qian X, Zinner MJ, Mortelé KJ. Pancreatic PEComa (sugar tumor): MDCT and EUS features. JOP. 2009;10:679–82.PubMedGoogle Scholar
  11. Zemet R, Mazeh H, Neuman T, Freund HR, Eid A. Asymptomatic pancreatic perivascular epithelial cell tumor (PEComa) in a male patient: report and literature review. JOP. 2011;12:55–8.PubMedGoogle Scholar
  12. Nagata S, Yuki M, Tomoeda M, Kubo C, Yoshizawa H, Kitamura M, et al. Perivascular epithelioid cell neoplasm (PEComa) originating from the pancreas and metastasizing to the liver. Pancreas. 2011;40:1155–7.View ArticlePubMedGoogle Scholar
  13. Finzi G, Micello D, Wizemann G, Sessa F, Capella C. Pancreatic PEComa: a case report with ultrastructual localization of HMB-45 within melanosomes. Ultrastruct Pathol. 2012;36:124–9.View ArticlePubMedGoogle Scholar
  14. Al-Haddad M, Cramer HM, Muram T, Wang X, Pitt HA. Perivascular epithelioid cell tumor: an unusual pancreatic mass diagnosed by EUS-FNA. Gastrointest Endosc. 2013;78:165–7.View ArticlePubMedGoogle Scholar
  15. Okuwaki K, Kida M, Masutani H, Yamauchi H, Katagiri H, Mikami T, et al. A resected perivascular epithelioid cell tumor (PEComa) of the pancreas diagnosed using endoscopic ultrasound-guided fine-needle aspiration. Intern Med. 2013;52:2061–6.View ArticlePubMedGoogle Scholar
  16. Mourra N, Lazure T, Colas C, Arrive L, de Gramont A. Perivascular epithelioid cell tumor: the first malignant case report in the pancreas. Appl Immunohistochem Mol Morphol. 2013;21:e1–4.View ArticlePubMedGoogle Scholar
  17. Petrides C, Neofytou K, Khan AZ. Pancreatic perivascular epithelioid cell tumour presenting with upper gastrointestinal bleeding. Case Rep Oncol Med. 2015;431215.Google Scholar
  18. Goldblum JR, Folpe AL, Weiss SW. Enzinger & Weiss’s soft tissue tumors. 6th ed. Philadelphia, PA: Elsevier Saunders; 2014.Google Scholar
  19. Huang J, Luo RK, Du M, Zeng HY, Chen LL, Ji Y. Clear cell sarcoma of the pancreas: a case report and review of literature. Int J Clin Exp Pathol. 2015;8:2171–5.PubMedPubMed CentralGoogle Scholar
  20. Crino PB, Nathanson KL, Henske EP. The tuberous sclerosis complex. N Engl J Med. 2006;355:1345–56.View ArticlePubMedGoogle Scholar
  21. Dabora SL, Jozwiak S, Franz DN, Roberts PS, Nieto A, Chung J, et al. Mutational analysis in a cohort of 224 tuberous sclerosis patients indicates increased severity of TSC2, compared with TSC1, disease in multiple organs. Am J Hum Genet. 2001;68:64–80.View ArticlePubMedGoogle Scholar
  22. Bissler JJ, Kingswood JC, Radzikowska E, Zonnenberg BA, Frost M, Belousova E, et al. Everolimus for angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis (EXIST-2): a multicentre, randomised, double-blind, placebo-controlled trial. Lancet. 2013;381:817–24.View ArticlePubMedGoogle Scholar

Copyright

© The Author(s). 2016