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Year : 2015  |  Volume : 52  |  Issue : 4  |  Page : 697--698

Bizarre leiomyoma of uterus/smooth muscle tumor of uncertain malignant potential: A diagnostic dilemma

SY Swami, RD Ganjewar, S Gaikwad, DD Girji 
 Department of Pathology, S. R. T. R. Medical College, Ambajogai, Maharashtra, India

Correspondence Address:
S Y Swami
Department of Pathology, S. R. T. R. Medical College, Ambajogai, Maharashtra

How to cite this article:
Swami S Y, Ganjewar R D, Gaikwad S, Girji D D. Bizarre leiomyoma of uterus/smooth muscle tumor of uncertain malignant potential: A diagnostic dilemma.Indian J Cancer 2015;52:697-698

How to cite this URL:
Swami S Y, Ganjewar R D, Gaikwad S, Girji D D. Bizarre leiomyoma of uterus/smooth muscle tumor of uncertain malignant potential: A diagnostic dilemma. Indian J Cancer [serial online] 2015 [cited 2020 Aug 8 ];52:697-698
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In 1972, Christopherson WM, Williamson EO, and Gray LA specifically described 17 bizarre leiomyomas that were culled from a large group of uterine tumors with a prior diagnosis or suspicion of sarcoma. According to World Health Organization (WHO) classification, bizarre leiomyoma is defined as “leiomyoma containing giant cells with pleomorphic nuclei and little or no mitotic activity.” In 1909, Kelly and Cullen in their monograph on myomata of uterus described several tumors that macroscopically had the usual appearance of myomata but histologically contained cells suggestive of “sarcomatous degeneration,” including large multinucleated tumor cells. In the subsequent classification developed for WHO, Christopherson's term bizarre leiomyoma was adopted, and symplastic leiomyoma and pleomorphic leiomyoma were acknowledged as synonymous designations. Bizarre leiomyoma was defined as a leiomyoma containing giant cells with pleomorphic nuclei and little or no mitotic activity.[1]

A 50-year-old, gravida 7 menopausal female came to outpatient department with chief complaints of pain in abdomen and intermittent spotting since 8-10 days. Clinical examination revealed a 14-16 weeks anteverted uterus. Ultrasonography showed a 9.2 × 8.5 cm large circular hypoechoic lesion in the uterine cavity without any cystic change or calcification. Clinical diagnosis of fibroid uterus was kept and total abdominal hysterectomy with bilateral salphingo-oopherectomy was done.

On gross [Figure 1], an already cut opened uterus of size 14 × 7 × 6 cm with bilateral adnexa was received. A submucosal fibroid of size 9 × 8 × 5 cm was attached to the fundus of uterus on posterior wall.{Figure 1}

Microscopy [Figure 2],[Figure 3],[Figure 4] showed a cellular tumor composed of interlacing bundles of spindle-shaped cells with moderate to severe cellular and nuclear pleomorphism, atypia, hyperchromatic nuclei, and multinucleated form. These changes were seen diffusely throughout the tumor. Mitotic figures counted were <10/10 high power fields (HPFs) in most cellular areas. No coagulative necrosis, epitheloid cells, or myxoid areas were seen. A diagnosis of bizarre leiomyoma was kept. But immunohistochemistry (IHC) was positive for smooth muscle actin without overexpression of MIB-1. Final opinion kept was Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP).{Figure 2}{Figure 3}{Figure 4}

The term atypical leiomyoma is reserved for those tumors with abnormal nuclei, some of which have malignant criteria. The nucleus may be multilobated and is not excessively hyperchromatic.[2]

The age, presenting symptoms, size of the leiomyoma, and other gross features in our case were according to other studies.[1],[3]

The diagnostic approach to each uterine smooth muscle neoplasm was as follows:First the tumor was examined under low magnification to determine the degree of atypia – mild (insignificant) or moderate to severe (significant). The sections were then evaluated for presence or absence of necrosis. If the atypia is significant and there is no necrosis or only hyaline necrosis, the tumors are interpreted as leiomyoma irrespective of mitotic activity. This approach also helps to avoid over diagnosis of leiomyomas with unusual histological patterns as malignant. If atypia is significant, a search is made for necrosis. If coagulative tumor cell necrosis (CTCN) is present, tumor is leiomyosarcoma regardless of mitotic counts. If necrosis is absent or is of hyaline type, a mitotic count is made and further classification is based on Mitotic Index (MI). A bivariate rule employing MI and cytological feature performed better than either MI or atypia. Trivariate approach that used MI, degree of atypia, and CTCN tends to ameliorate interpretive difficulties.

Taylor and Norris used 10 or more mitosis per 10 HPFs as the lowest level for inclusion of sarcoma. The microscopic features like circumscribed margins and hyalinization were comparable to the study done by Christopherson et al.[4]

On H and E, we concluded that uterine myomatous tumor with gross and microscopic features reported in our case as bizarre leiomyoma was clinically benign even when cellularity was high, giant forms were numerous and distributed diffusely, and even if some mitotic activity was present with mitotic figure <10/10 HPFs.

But the diagnosis was changed to STUMP on IHC. Hence, we conclude that IHC is required whenever there is diagnostic dilemma on H and E.


We are thankful to Professor and Head, Department of Pathology, AFMC Pune, for IHC and expert opinion.


1Downes KA, William RH. Bizarre leiomyomas of the uterus. A comprehensive pathologic study of 24 cases with long term follow-up. Am J Surg Pathol 1997; 21:1261-70.
2Robert EF. Atypical leiomyoma and synthetic progestin therapy. Am J Clin Pathol 1968; 49:697-703.
3Burns B, Curry RH, Bell ME. Morphologic features of prognostic significance in uterine smooth muscle tumors. A review of eighty-four cases. Am J Obstet Gynecol 1979;135:109-14.
4Christopherson WM, Williamson EO, Gray LA. Leiomyosarcoma of the uterus. Cancer 1972; 29:1512-7.