Leiomyoma of the breast: an uncommon tumor

1. Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Mailing address: Richard C. Semelka, MD. UNC Department of Radiology. 101 Manning Drive CB#7510 – 2001 Old Clinic Bldg. Chapel Hill, NC 27599-7510, USA. E-mail: [email protected]. destruens is a locally invasive (myometrium) manifestation of complete HM that represents 13% of cases of GTD. Two percent of complete HM cases are described as choriocarcinoma, which is locally invasive and potentially metastasizing. These three entities produce peculiarly high levels of β-hCG, while placental site trophoblastic tumor causes a rise in human placental lactogen levels, and less elevated β-hCG levels. Clinical assessment is difficult early in the course of the disease, as few clinical characteristics are present to distinguish it from a normal pregnancy. Pelvic MRI is often used as a problem-solving tool in equivocal or complicated cases of GTD, especially in the first trimester, or to assess the degree of myometrial invasion and surrounding tissues. Early manifestations appear as a soft tissue cystic mass with high T2 signal intensity. In the second trimester these lesions tend to distend the endometrium giving a “cluster of grapes appearance”. Typically HMs are similar or slightly higher in T1 signal intensity than the adjacent myometrium. Contrast-enhanced MRI show areas of focal enhancement that relate to the amount of active trophoblastic tissue and also to β-hCG levels. Marked early enhancement indicates active disease in the form of viable trophoblastic tissue. In the setting of GTD, identification of myometrial invasion is crucial for diagnosis and staging. Uterine tumors associated with high serum β-hCG have a high incidence of myometrial contractions. Myometrial contractions are seen as a bulge of the myometrial wall usually along with a region of low T2 signal intensity in the myometrium. They are transient and tend to disappear on subsequent data acquisitions, as observed in our case. In the setting of endometrial tumor, radiologists should be aware of this phenomenon to avoid over-diagnosis and over-staging by misdiagnosing uterine contraction with myometrial extension or invasion. REFERENCES