Can fibromuscular dysplasia (FMD) affect the spleen?

From the Guidelines

Fibromuscular dysplasia (FMD) typically does not affect the spleen directly, as it primarily affects medium-sized arteries, most commonly the renal and carotid arteries. FMD is a non-inflammatory, non-atherosclerotic vascular disease that can theoretically affect any arterial bed, but involvement of the splenic artery is extremely rare 1. When FMD does affect the splenic artery, it could potentially lead to splenic ischemia, infarction, or aneurysm formation, but these complications are not commonly reported in clinical practice. The disease predominantly affects women between 30-50 years of age and typically manifests with hypertension (when renal arteries are involved) or neurological symptoms (when carotid or vertebral arteries are affected) 1.

Key Points to Consider

• FMD is a rare disease with unknown exact cause, though genetic factors, hormonal influences, and mechanical factors may contribute to its development 1.
• Patients with suspected FMD should undergo comprehensive vascular imaging, typically with CT angiography, MR angiography, or catheter-based angiography to identify the characteristic "string of beads" appearance in affected arteries 1.
• Annual noninvasive imaging of the carotid arteries is reasonable initially for patients with FMD to detect changes in the extent or severity of disease, although the effect on outcomes is unclear 1.
• Administration of platelet-inhibitor medication can be beneficial in patients with FMD of the carotid arteries to prevent thromboembolism, but the optimum drug and dosing regimen have not been established 1.

Clinical Implications

• The primary concern in managing FMD is to prevent complications such as thromboembolism, dissection, and aneurysm formation, and to manage symptoms related to the affected arteries 1.
• Given the rarity of splenic involvement, routine screening for splenic artery FMD is not recommended, but comprehensive vascular imaging should be considered in patients with suspected FMD to identify any potential involvement of other arterial beds 1.

From the Research

Fibromuscular Dysplasia and the Spleen

• There is no direct evidence in the provided studies that fibromuscular dysplasia (FMD) affects the spleen.
• FMD is described as a disease that can affect all layers of both small- and medium-calibre arteries, with the most common sites being the renal, carotid, and vertebral arteries 2, 3, 4, 5, 6.
• The studies focus on the diagnosis, management, and treatment of FMD in various arteries, including the renal and carotid arteries, but do not mention the spleen as a potential site of involvement.
• The lack of information on FMD affecting the spleen suggests that it may not be a common or well-documented association, but it does not rule out the possibility entirely.

Arteries Affected by FMD

• The renal arteries are commonly affected by FMD, with a prevalence estimated between 4 and 6% 2.
• The carotid and vertebral arteries are also frequently involved, with FMD being a non-atherosclerotic and non-inflammatory disease that can cause stenosis, aneurysm, dissection, and other vascular abnormalities 3, 4.
• Other arteries, such as the coronary arteries, can also be affected by FMD, although this is less common 4.

Diagnosis and Management of FMD

• Radiologists play a crucial role in the diagnosis of FMD, with imaging techniques such as angiography being used to visualize the affected arteries 2, 3.
• Treatment options for FMD include medical management, endovascular procedures such as percutaneous transluminal angioplasty, and surgical intervention 5, 6.
• The management of FMD is often tailored to the individual patient, depending on the severity of the disease, the presence of symptoms, and the involvement of specific arteries.