Picture1Tumor is grossly involving uterine serosa Picture2Myometrium with lymphovascular tumor invasion 
  Picture3Detail of tumor with cellular perivascular areas  

Clinical history:

49 year-old-female with pelvic mass and diffuse pulmonary lesions

Gross examination:

Tumor is present in the uterus and surrounding tissue (“pelvic mass”), total size 19.0 cm

Microscopic examination:

Tumor within myometrium with stromal and lymphovascular invasion and in “pelvic mass”. No mitoses are identified.

Immunohistochemical stains:

                -Positive: ER, PR, SMA, desmin, HMB-45, MiTF

                -Negative: CD10, CK LMW (CAM 5.2), CK HMW (34BE12), DOG1.

Choose the correct diagnosis:

  1. Endometrial stromal sarcoma
  2. Perivascular epithelioid cell neoplasm
  3. Intravascular leiomyomatosis
  4. Gastrointestinal stromal tumor

Answer:  “B.”  Perivascular epithelioid cell neoplasm (PEComa)

Discussion:

Age: Reproductive age and postmenopausal women

Clinical features: Uterine bleeding. Associated with lymphangioleiomyomatosis  and tuberous sclerosis

Histology: Cells with well defined borders and abundant clear cytoplasm or  spindle cells. Cells may be tightly arranged around blood vessels.  Low mitotic activity. Occasional stromal hyalinization

IHC: Positive for HMB-45, MiTF; variably positive for SMA, CD10; negative for cytokeratin

Behavior/prognosis:

Benign, borderline,malignant.

Aggressive behavior: >5 cm, infiltrative growth pattern, high-grade cytologic atypia, necrosis, mitotic activity 1/50HPF.

 Presented case has an aggressive behavior based on the large tumor size,  LVI and diffuse lesions in the lungs

 

Literature:

Perivascular Epithelioid Cell Neoplasm (PEComa) of the Gynecologic Tract. Clinicopathologic and Immunohistochemical Characterization of 16 Cases

John Kenneth Schoolmeester, MD, Brooke E. Howitt, MD, Michelle S. Hirsch, MD, PhD, Paola Dal Cin, PhD, Bradley J. Quade, MD, PhD,w and Marisa R. Nucci, MD. Am J Surg Pathol 2014;38:176-188

Case contributed by Lea Novak, M.D., Associate Professor, Anatomic Pathology