The answer:
Fibromuscular disease (FMD)
The Case
What's the diagnosis?
- Renal artery involvement ≈ 60% to 75% of cases and ≈35% bilateral
- Carotid or vertebral arteries involvement ≈ 25%-30% of cases.
- Intracranial involvement rare
- ≈ 28% of cases multiple arterial systems are involved- renal arteries are almost always involved.
- FMD classified histologically according to whether it predominately affects the arterial media, intima, or adventitia.
- Medial dysplasia
- 3 histologic types:
- Medial fibroplasia ≈ 75% to 80% of all cases of FMD; characteristic string of beads with diameters larger than the normal artery size in the middle and distal portion of the main renal arteries and its branches. On histologic cross-section of the artery, the media has both very thin and very thick areas without inflammatory cells. The thin areas may develop aneurysms in a minority of patients.
- Perimedial fibroplasia: less than 10% of cases of FMD. It tends to occur in girls between 5 and 15 years old. It may progress to renal failure if left untreated. Perimedial disease also resembles a string of beads but with fewer beads and with diameters smaller than the normal artery size. Collateral arteries often form around the area of stenosis. Histologically, there is extensive collagen deposition in the outer half of the media.
- Medial hyperplasia is rare. It appears angiographically as a concentric focal band and histologically as smooth muscle cell hyperplasia without fibrosis. Medial hyperplasia resembles intimal fibroplasia and may not be a distinct condition.
- Intimal fibroplasia: less than 10% of cases of FMD.
- Adventitial (periarterial) fibroplasia: less than1% of FMD.
The Case
What's the diagnosis?
