A 47 y.o. woman is sp hysterectomy for fibroids and presents with a LLQ mass

What could be causing this mass?

Our patient had a malignant transformation of a leiomyoma into a leiomyosarcoma.  The lesion on the flank was metastatic sarcoma. One in 386 women undergoing a hysterectomy for presumed fibroids has a hidden sarcoma according to one study. There is some evidence that morcellation of a fibroid (using a small bladed device to chop up the fibroid so it can be removed laparoscopically) can lead to malignant transformation and peritoneal disease.

Fibroids are  clinically detectable in 25%to 80% of women in community-based studies with many women having the disease not being symptomatic. African-American women suffer fibroids at 2-3 times the rate of white women. They get fibroids at a younger age and often more severe symptoms.

A large leiomyoma was found to have microscopic foci of sarcoma

Our patient had a hysterectomy  in 2018 and in six months noted a swelling on the L flank.  This continued to grow and was biopsied showing sarcoma.  Presumably,  the original specimen would have shown microscopic foci of sarcoma.  7/20  she underwent biopsy of the metastasis followed by XRT and doxorubicin.  2/21 the metastasis was removed.   She was seen in the ED for abdominal pain which resolved but  has been well since that time.

This patient had morcellation of a leiomyomatous uterus and presented 28 months later with metastatic sarcoma

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