= Solution
\b[The principal modes are growth within the uterine wall, towards the cavity, and towards the outer surface: <intramural uterine fibroids>, <submucosal uterine fibroids> and <subserosal uterine fibroids>.] “Fibrous tumour” is the historical label; the usual modern lesion is a <leiomyoma>, a benign growth of <smooth muscle> with a variable connective-tissue component, rather than a mass of collagen alone.<Uterine Fibroids by the American College of Obstetricians and Gynecologists>[Overview: muscle origin and variation in size, shape and location]{ref}
An <intramural uterine fibroid> enlarges within the <myometrium>. It can remain enclosed by uterine muscle, push the cavity aside, or expand both inner and outer contours. Several nodules can give an irregularly enlarged <uterus>. Expansion compresses surrounding tissue into a cleavage plane or pseudocapsule; this differs from the destructive infiltrative growth typical of a malignant lesion.
A <submucosal uterine fibroid> grows towards the <endometrium>, projecting into and distorting the uterine cavity. It may remain broad-based or acquire a stalk as the surrounding wall is displaced. A <pedunculated uterine fibroid> can be pushed through the cervical canal and appear in the <vagina> as a <uterine polyp>. A polyp formed in this way is a mode of presentation of the same smooth-muscle tumour, not necessarily a different histological species. Its relation to the cavity helps explain why a comparatively small lesion may be associated with substantial bleeding.
A <subserosal uterine fibroid> projects outwards beneath the serosal covering. It may have a broad attachment or a long pedicle and become a large extrauterine-looking mass. Lateral outward growth can extend between the layers of the broad ligament; cervical growth can displace neighbouring pelvic structures. Rarely, a detached pedunculated lesion gains a blood supply from adjacent tissues and persists as a parasitic growth; this is not ordinary distant <metastasis>.<Uterine Fibroids by Merck Manual Professional Edition>[Anatomical locations: intramural, submucosal, subserosal, cervical, intraligamentous and parasitic forms]{ref}
The three directions are not mutually exclusive: a large nodule may affect both the uterine cavity and its external surface. Modern location classifications describe its relation to <endometrium>, <myometrium> and serosa more precisely, but those later type numbers are unnecessary to explain the anatomical modes requested here.
Growth is also distinct from secondary change. A poorly supplied area can undergo hyaline or cystic degeneration, haemorrhagic change or calcification; these changes alter consistency without establishing a new malignant mode of growth. <Uterine fibroids> often respond to the reproductive hormonal environment and commonly shrink after menopause, but neither every lesion's course nor its rate of growth is identical.<Uterine Leiomyomata in StatPearls>[Etiology, histopathology and secondary changes; hormone-related growth and postmenopausal involution]{ref} \b[Location and attachment describe the mode of expansion; tissue examination establishes the nature of the tumour.]
Back to article page
