Myxoid Smooth Tumors of the Uterus: Can Histology Predict Behavior?
Molly A Gurney, Anais Malpica, Elizabeth D Euscher. University of Texas MD Anderson Cancer Center, Houston, TX
Background: Myxoid smooth muscle tumors (MSMT) of the uterus are diagnostically problematic. Due to their rarity, their criteria for malignant behavior are not well defined with overlapping histologic features between clinically benign and malignant tumors. This clinicopathologic study represents the largest series of such cases to date.
Design: A 20 year search (1992-2012) of our pathology data base yielded 35 MSMT. 15 cases were excluded based on presence of conventional leiomyosarcoma (LMS) or containing <50% myxoid change. H&E slides were reviewed in all cases. The following parameters were recorded: patient (pt) age, stage of disease, tumor size, tumor border, % myxoid component, degree of cellularity, presence of coagulative tumor cell necrosis (CTCN), presence of marked atypia, mitotic index (MI), treatment and outcome.
Results: Pts ages ranged from 28 to 64 yrs (median 48) with 9 to 213 mos follow up (median 66) available for 16 pts. Stage of disease was known for 16 pts: Stage I, 13; Stage II, 3. 6 pts had a diagnosis of smooth muscle tumor of uncertain malignant potential (STUMP), and 14 pts had a diagnosis of LMS. 3 tumors had at least focally increased cellularity. 15 tumors had bland spindle cells, and 4 had epithelioid cells. Remaining pathologic features of cases with follow up by outcome are presented in Table 1;pathologic features by tumor diagnosis are presented in Table 2.
|Tumor Size (cm, median)||Infiltrative Tumor Border Present||% Myxoid (Median)||LVI Present||CTCN Present||Severe Atypia Present||MI (median)|
|No Evidence of Disease (n=13)||7||5||80||3||5||4||4|
|Recurrent/Dead of Disease (n=3)||10||2||90||1||3||0||9.5|
|Tumor Size (cm, median)||Infiltrative Border Present||% Myxoid (Median)||LVI Present||CTCN Present||Severe Atypia Present||MI (median)|