Uterine leiomyoma

Uterine leiomyoma, commonly fibroid, is a very common benign smooth muscle tumour of the uterus.

Uterine leiomyoma
Diagnosis in short
Uterine leiomyoma. H&E stain.
Synonyms	uterine fibroid
LM	spindle cells arranged in fascicles, usually without atypia
Subtypes	atypical leiomyoma (symplastic leiomyoma), lipoleiomyoma, cellular leiomyoma, others
LM DDx	leiomyosarcoma, STUMP, dermatomyofibroma, adenomatoid tumour
Gross	sharply circumscribed lesion, gray-white, whorled appearance
Grossing notes	Hysterectomy for fibroids grossing
Prevalence	very common
Prognosis	benign
Clin. DDx	other uterine tumours
Treatment	surgical (myomectomy, hysterectomy) or medical

The more general topic of leiomyoma is covered in the article leiomyoma.

General

• Extremely common... 40% of women by age 40.
• Benign.
  • Can be a cause of abnormal uterine bleeding (commonly abbreviated AUB).
• Large & multiple associated with infertility.
• May be treated medically with a selective progesterone receptor modulator, e.g. ulipristal (Fibristal).

Gross

Feature:

• Sharply circumscribed.
• Gray-white.
• Whorled appearance.

Factor that raise concern for leiomyosarcoma:

• Haemorrhage.
• Cystic degeneration.
• Necrosis.

Microscopic

Features:

• Spindle cells arranged in fascicles.
  • Fascicular appearance: adjacent groups of cells have their long axis perpendicular to one another; looks somewhat like a braided hair that was cut.
• Whorled arrangement of cells.

Negatives:

• Necrosis (low power) - suggestive of leiomyosarcoma.
• Hypercellularity.
• Nuclear atypia seen at low power.
• Few mitoses.

DDx:

• Leiomyosarcoma.
• Smooth muscle tumour of uncertain malignant potential (STUMP).
• Adenomatoid tumour.

Variants

• Lipoleiomyoma - with adipose tissue.
  • Image: Lipoleiomyoma - low mag. (WC).
• Hypercellular leiomyoma - hypercellularity associated with more mutations.
• Atypical leiomyoma (AKA symplastic leiomyoma) - leiomyoma with nuclear atypia.
  • Image: Atypical leiomyoma (WC).
• Benign metastasizing leiomyoma.
  • This is just what it sounds like. Some believe these are low grade leiomyosarcomas.

IHC

Work-up of suspicious leiomyomas:

• CD10 +ve.
• SMA +ve.
• Desmin +ve.
• Ki-67 -ve.

Others:

• p16 usually -ve.
  • Often +ve in leiomyosarcoma.
• H-caldesmon +ve.

Sign out

Uterine Cervix, Uterus, Bilateral Tubes and IUD, Total Hysterectomy and Bilateral Salpingectomy:
- Uterine leiomyomas.
- Mild atherosclerosis.
- Inactive endometrium.
- Intrauterine device (IUD) - gross only.
- Uterine cervix within normal limits.
- Left uterine tube with small paratubal cyst, negative for 
  significant pathology.
- Right uterine tube with paratubal cyst, negative for significant pathology.
- NEGATIVE for malignancy.

Block letters

UTERUS WITH CERVIX, UTERINE TUBES AND LEFT OVARY, TOTAL HYSTERECTOMY, BILATERAL SALPINGECTOMY 
AND LEFT OOPHRECTOMY:
- LEIOMYOMATA WITH FOCAL CALCIFICATION AND HYALINE CHANGE.
- SECRETORY PHASE ENDOMETRIUM.
- LEFT OVARY WITHIN NORMAL LIMITS.
- UTERINE TUBES WITHIN NORMAL LIMITS.
- UTERINE CERVIX WITHIN NORMAL LIMITS.

Myomectomy

UTERINE MASSES ("FIBROIDS"), MYOMECTOMY:
- LEIOMYOMATA.

UTERINE MASS, HYSTEROSCOPIC MYOMECTOMY:
- BENIGN SMOOTH MUSCLE FRAGMENTS COMPATIBLE WITH LEIOMYOMA.
- SECRETORY PHASE ENDOMETRIUM.

Micro

The sections show bland spindle cells within a fascicular architecture. Hyaline change is present. No necrosis is seen. Mild proliferative activity is seen (~ 2 mitoses/10 HPFs, 1 HPF ~0.2376 mm*mm). No cytologic atypia is apparent.

See also

• Uterine tumours.