Case 191 - Discussion

Uploaded: 2008-02-28, Updated: 2008-09-12



Vimentin LCA

Inhibin Desmin



Uterine Cellular Leiomyoma


Grossly, this uterine tumor is pale, tan and well-demarcated with softer consistency than the classic leiomyomas. Microscopically, this highly cellular tumor consists of uniform small round or oval neoplastic cells with moderate amount of pale pink cytoplasm. The nuclei are round, oval, angular or slightly elongated with occasional nuclear groove and one small or inconspicuous central nucleolus. There is no significant atypia, marked mitoses or necrosis seen in this case. By immunohistochemistry stainings, the neoplastic cells are strongly positive for smooth muscle markers (SMA and Desmin), but negative for uterine stromal markers (CD10). The histology and immunoprofile support a diagnosis of a benign smooth muscle tumor of the uterus with high cellularity, uterine cellular leiomyoma.

Uterine cellular leiomyoma accounts for less than 5% of uterine leiomyomas. Grossly, the tumor is usually well circumscribed and is tan, brown or yellow with a softer consistency than the conventional leiomyomas. Histologically, the tumor shows high cellularity with uniform and bland tumor cells. The tumor cells are typically arranged in fascicles with cleft-like spaces and large thick-walled vessels. The mitotic count is usually less than 5 per 10 high-power fields. The differential diagnosis of this case should include an endometrial stromal tumor and a low-grade uterine smooth muscle neoplasm. This case shows positivity for smooth muscle markers but no reaction to uterine stromal markers, ruling out of stromal tumor. The lack of atypia, high mitoses and necrosis indicate a benign nature of the neoplasm.


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