Extrapulmonary clear cell tumour, PEComa

Definition

A tumour composed of epithelioid or spindle cells with clear or lightly eosinophilic cytoplasm and showing positivity for at least one or either HMB45 or Melan-A. Co-expression of melanocytic and myoid markers is required for morphologically atypical cases.

Epidemiology

There is a strong female predominance, even for tumours outside the female genital tract. Very few cases are associated with tuberous sclerosis11.

Clinical features

Clear cell tumours are members of the family of PEComas and most commonly occur in the lung. Extrapulmonary sites include soft tissue8, base of skull11, trachea2, breast1, heart5, ligamentum teres, pancreas3, rectum5, bladder11, uterus4, vulva11 and perineum5.

Macroscopic appearances

The tumour may be circumscribed or infiltrative.

Histopathology

The tumour cells are clear or lightly eosinophilic and either epithelioid or spinded. They typically grow radially around blood vessels.

Immunohistochemistry

Cam5.2

0/11, 0/13, 0/17

 

AE1/3

0/11, 0/13, 0/17, 3/2312

KL1

0/13

Pancytokeratin

0/16, 0/18, 0/19

CK7

0/17

Desmin

0/11, 0/17, 0/18, 1/19, 0/110, 8/2212

Muscle-specific actin

0/11, 0/17, 1/19

SMA

0/11, 0/16, 1/17, 1/18, 1/19, 0/110, 20/2512

S-100

0/11, 0/16, 0/17, 0/18, 0/19, 0/110, 8/2412

HMB45

1/11, 1/13, 1/14, 4/45, 1/16, 1/17, 1/18, 1/19, 1/110, 22/2412

Melan-A (MART-1)

1/11, 0/16, 0/17, 1/19, 13/1812

Co-expression of (HBM45 or Melan-A) and SMA

20/2412

MiTF

9/1812

TFE3

5/1712

NKI/C3

1/19

KBA.62

0/19

Oestrogen receptor

0/11, 1/19, 0/110

Progesterone receptor

1/11, 0/19, 1/110

EMA

0/11, 0/16, 0/17, 0/19

Vimentin

0/11, 0/16, 0/17, 1/110, 12/1412

NSE

0/11, 0/13, 1/16, 0/17

Chromogranin A

0/11, 0/13, 0/16, 0/17, 0/19

Synaptophysin

0/11, 0/16, 0/17

Neu-N

0/17

CEA

0/11, 0/17, 0/19

CD10

1/19

CD31

0/11

CD34

0/11, 0/18, 0/19, 0/110, 0/712

CD45

0/17, 0/18

 

CD99

1/17

 

CD117

1/19, 1/110, 1/2012

 

Alpha-fetoprotein

0/17

 

Placental alkaline phosphatase

0/17

 

b-HCG

0/17

 

p16

0/110

 
 

 

Differential diagnosis

Site

Differential

distinguishing features

 

General 

clear cell carcinoma, glycogen-rich

cytokeratin positive, HMB-45 negative

clear cell carcinoma, lipid-rich

cytokeratin positive, HMB-45 negative

metastatic melanoma

HMB-45 positive

Abdomen

GIST: PEComa may be CD117+

 

Kidney

renal clear cell carcinoma

cytokeratin positive, HMB-45 negative

Breast

clear cell adenomyoepithelioma

cytokeratin, actin and S-100 positive, HMB-45 negative

Breast

clear cell myoepithelioma

cytokeratin, actin and S-100 positive, HMB-45 negative

Base of skull

chordoma, chondrosarcoma, meningioma, pituitary adenoma, haemangioblastoma

 

Soft tissues 

clear cell sarcoma of soft tissue

S-100 positive

clear cell rhabdomyosarcoma

desmin, myogenin, myoD1 positive

alveolar soft part sarcoma

PAS positive

 

Prognosis

The presence of an infiltrating margin, mitoses, necrosis and nuclear pleomorphism are associated with metastatic behaviour.

References

1Govender, D., Sabaratnam, R.M. and Essa, A.S. Clear cell 'sugar' tumor of the breast: another extrapulmonary site and review of the literature. Am J Surg Pathol 2002;26:670-5.

2Kung, M., Landa, J.F. and Lubin, J. Benign clear cell tumor ("sugar tumor") of the trachea. Cancer 1984;54:517-9.

3Zamboni, G., Pea, M., Martignoni, G., Zancanaro, C., Faccioli, G., Gilioli, E., Pederzoli, P. and Bonetti, F. 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.

4Pea, M., Martignoni, G., Zamboni, G. and Bonetti, F. Perivascular epithelioid cell. Am J Surg Pathol 1996;20:1149-53.

5Tazelaar, H.D., Batts, K.P. and Srigley, J.R. Primary extrapulmonary sugar tumor (PEST): a report of four cases. Mod Pathol 2001;14:615-22.

6Sadeghi, S., H. Krigman, et al. (2004). "Perivascular epithelioid clear cell tumor of the common bile duct." Am J Surg Pathol 28(8): 1107-10.

7Lehman, N. L. (2004). "Malignant PEComa of the skull base." Am J Surg Pathol 28(9): 1230-2.

8Harris, G. C., T. A. McCulloch, et al. (2004). "Malignant perivascular epithelioid cell tumour ("PEComa") of soft tissue: a unique case." Am J Surg Pathol 28(12): 1655-8.

9Evert M, Wardelmann E, Nestler G, et al. Abdominopelvic perivascular epithelioid cell sarcoma (malignant PEComa) mimicking gastrointestinal stromal tumour of the rectum. Histopathology 2005; 46:115-7

10Park SH, Ro JY, Kim HS, et al. Perivascular epithelioid cell tumor of the uterus: immunohistochemical, ultrastructural and molecular study. Pathol Int 2003; 53:800-5

11 Hornick JL,Fletcher CD. PEComa: what do we know so far? Histopathology 2006; 48:75-82

12 Folpe AL, Mentzel T, Lehr HA, et al. 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 [omentum or mesentery (6 cases), uterus (4 cases), pelvic soft tissues (3 cases), abdominal wall (2 cases), uterine cervix (2 cases), and vagina, retroperitoneum, thigh, falciform ligament, scalp, broad ligament, forearm, shoulder, and neck (1 case each)]

This page last revised 25.5.2006.

©SMUHT/PW Bishop