Fibroadipose Vascular Anomaly: A Distinct Vascular Malformation

Fibroadipose vascular anomaly (FAVA) is a rare and complex vascular malformation. It primarily involves the venous components and is characterised by a matrix of fibrofatty tissue. This study aimed to describe the features of FAVA that differentiate it from venous malformation (VM).

A retrospective series of 62 patients diagnosed with FAVA from August 2019 to February 2022 at a tertiary care centre in South India was analysed. The diagnosis was confirmed by histopathology (n = 35) or characteristic magnetic resonance imaging (MRI) findings (n = 27), reviewed by a multidisciplinary team. For the radiological analysis, 21 cases (with proven biopsy, in hospital MRI, and no prior intervention) of FAVA were selected; these were compared with 36 patients with slow flow peripheral VMs confirmed by MRI.

FAVA (43.5% males) and VM (55.6% males) presented at a mean age of 26.5 ± 13.1 and 23.7 ± 10.9 years, respectively. While both presented with swelling (93.7% and 94.4%, respectively), pain was significantly more prevalent among FAVA (87.1% vs. 52.8%). FAVA predominantly affected the lower limbs (79%), while VMs had a broader distribution. FAVA was misdiagnosed in 74% of cases, most commonly as VMs. On MRI, FAVAs more frequently demonstrated an intramuscular lesion (90.5% vs. 19.4%; p < .001) with fat proliferation (95.2% vs. 5.5%; p < .001) and fibrosis (90.5% vs. 2.7%; p < .001). FAVAs were also associated with periosteal reaction of bones (28.6% vs. 0%; p < .001) and neural encasement (14.3% vs. 2.7%; p = .26). Both FAVA and VM had vascular spaces (66.7% vs. 80.6%) in which VMs more frequently exhibited phleboliths (52.8% vs. 23.8%; p = .033) and fluid levels (33.9% vs. 0%; p < .001), while FAVA showed the presence of thrombus (61.9% vs. 22.2%; p = .003).

FAVA is a clinically and radiologically distinct entity. Recognition of the characteristic MRI features of FAVA, particularly intramuscular fat and fibrosis, may aid in early diagnosis and guide appropriate multidisciplinary management.