Myometrium

Question 1

Smooth Muscle Tumours

Answer 1

Leiomyoma
* still have metastatic potential –> ‘benign metastasizing leiomyoma
* Variants:
Cellular leiomyoma
Leiomyoma with bizarre nuclei (no mitoses or necrosis)
Mitotically active leiomyoma (no atypia or necrosis)

Smooth Muscle Tumour of Uncertain Potential ‘STUMP’
* Equivocal mitoses or necrosis

Leiomyosarcoma
* Malignant smooth muscle tumour
* High grade cytological atypia
* Increased mitoses
* Tumour type necrosis
* Very poor prognosis

Question 2

Leiomyomas

Answer 2

• Intramural, submucosal, subserosal
• Occur more frequently in women receiving progesterone therapy
• OCP decreases risk
• If tons, and at a young age, consider –> Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome

Mitotically active Leiomyoma
* Women in reproductive age
* Associated with secretory endometrium, pregnancy, progesterone and Tamoxifen
* Increased mitotic activity –> 6-15/10 hpf
* No cytological atypia
* No tumour cell necrosis
* Extensive sampling is very important

Fumarate Hydratase Deficient Leiomyoma
* Somatic or Germlime FH mutation
* Loss of Fumarate Hydratase
* Presents with symptomatic uterine an cutaneous leiomyomas in 2nd-3rd decade of life
* Young women with these should be referred to genetic counselling to exclude HLRCC

Question 3

Leiomyosarcoma

Answer 3

Conventional (spindle cell) uterine leiomyosarcoma
Two or more of the following:
* Marked cytological atypia
* Tumour cell necrosis
* >4 mitoses/mm2 (= >10 mitoses/10 hpf)

Epithelioid uterine leiomyosarcoma
One or more of the following:
* Moderate to severe cytological atypia
* Tumour cell necrosis
* >1.6 mitoses/mm2 (= >4 mitoses/10 hpf)

Myxoid uterine leiomyosarcoma
One or more of the following:
* Moderate to severe cytological atypia
* Tumour cell necrosis
* >0.4 mitoses/mm2 (= >1 mitoses/10 hpf)

HC
* desmin
* SMA
* myosin
* ER, PR
* EMA3