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 3.
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 leucocytosis.
Carneous degeneration is a subtype of haemorrhagic infarction of leiomyomas that often occurs during pregnancy. On gross pathology, it is characterised by a red (haemorrhagic) appearance of the leiomyoma. Red degeneration primarily occurs secondary to venous thrombosis within the periphery of the tumour or rupture of intratumoral arteries 4.
Unusual signal intensity patterns have been described on pelvic MR imaging 1,4:
- 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 methaemoglobin
- 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 hypothesised that the blood products are confined to thrombosed vessels that surround the tumour
- 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 methaemoglobin in these vessels
- T1 C+ (Gd): variable enhancement
- 1. Kawakami S, Togashi K, Konishi I et-al. Red degeneration of uterine leiomyoma: MR appearance. J Comput Assist Tomogr. 18 (6): 925-8. - Pubmed citation
- 2. Ueda H, Togashi K, Konishi I et-al. Unusual appearances of uterine leiomyomas: MR imaging findings and their histopathologic backgrounds. Radiographics. 1999;19 Spec No : S131-45. - Pubmed citation
- 3. Dildy GA, Moise KJ, Smith LG et-al. Indomethacin for the treatment of symptomatic leiomyoma uteri during pregnancy. Am J Perinatol. 1992;9 (3): 185-9. doi:10.1055/s-2007-999317 - Pubmed citation
- 4. Murase E, Siegelman ES, Outwater EK et-al. Uterine leiomyomas: histopathologic features, MR imaging findings, differential diagnosis, and treatment. Radiographics. 19 (5): 1179-97. Radiographics (full text) - Pubmed citation
- 5. Elizabeth Kagan Arleo, Peter E. Schwartz, Pei Hui, Shirley McCarthy. Review of Leiomyoma Variants. (2015) American Journal of Roentgenology. 205 (4): 912-21. doi:10.2214/AJR.14.13946 - Pubmed