Red degeneration of a leiomyoma
Red or carneous degeneration is one of four main types of degeneration that can involve a uterine leiomyoma. While it is an uncommon type of degeneration, it is thought to be the most common form of degeneration of a leiomyoma during pregnancy .
Patients with a leiomyoma undergoing red degeneration may present with abdominal pain (particularly during pregnancy). It may also give systemic symptoms such as fever and leukocytosis.
Carneous degeneration is a subtype of hemorrhagic infarction of leiomyomas that often occurs during pregnancy. On gross pathology, it is characterized by a red (hemorrhagic) appearance of the leiomyoma. Red degeneration primarily occurs secondary to venous thrombosis within the periphery of the tumor or rupture of intratumoral arteries .
Unusual signal intensity patterns have been described on pelvic MR imaging :
- can have peripheral (rim) or diffuse high signal intensity
- high signal intensity on T1-weighted images is likely secondary to the proteinaceous content of the blood or the T1-shortening effects of methemoglobin
- variable signal intensity with or without a low-signal-intensity rim
- when high signal intensity is isolated to the rim of the leiomyoma, it has been hypothesized that the blood products are confined to thrombosed vessels that surround the tumor
- when it shows rim - peripheral changes these findings were thought to correspond to numerous dilated vessels filled with red blood cells at the periphery of the lesion
- the signal characteristics of the rim are best explained as an effect of abundant intracellular methemoglobin in these vessels
- T1 C+ (Gd): variable enhancement