Fibro-Adipose Vascular Anomaly (FAVA): Not Another Vascular Anagram

Background. Fibro-adipose vascular anomaly (FAVA) is a rare benign mesenchymal lesion. Characterized primarily by intramuscular vascular malformation with secondary overgrowth of other mesenchymal elements, particularly fibro-adipose tissue, the condition is sometimes complicated by nonspecific clinical and imaging features, causing diagnostic dilemma. Herein, we attempted to outline and correlate the clinical characteristics, imaging findings, and histopathological features of this unusual entity. Method. The study design was retrospective in nature. Computerized database of our institute was searched for tumors, and archived slides were reviewed. Pertinent clinical data including imaging findings and treatment details were also recovered for correlation. Result. Among total of 24 patients identified, mean age was approximately 16 years, with the presence of nearly equal gender distribution. Pain along with swelling was most common symptoms with the presence of movement limitation, in few. Most lesions were long-standing and anatomically confined to lower limb with no side predilection. Using imaging, the majority of the lesions were identified as vascular anomaly or venous malformation, with FAVA being a differential diagnosis in few lesions. However, in a couple of patients, likelihood of mesenchymal tumors was also suggested, radiologically. On histology, the lesions showed the presence of clustered back to back, abnormal thin-walled, variably dilated, blood-filled sac-like vessels amid skeletal muscle bundles, along with extensive fibro-adipose tissue and variably atrophic skeletal muscle bundles, at the periphery, diagnostic of FAVA. Conclusion. Owing to the presence of overlapping clinical and imaging features, FAVA is often misdiagnosed, causing dilemma in clinical management. Clinical, radiological, and histopathological correlation is thereby warranted for clinching the correct diagnosis.