Unusual multicentric angiomyolipoma of knee joint and soft tissue foot

Abstract

To report unusual occurrence of angiomyolipoma at intraarticular location with another lesion in the same side foot. A 12-year-old girl was referred to us after initial inconclusive work-up done elsewhere for swelling of left knee joint. There was a 15 × 12 cm swelling in the knee joint partially encasing patella while also a similar hourglass shaped swelling measuring 9 × 4 cm was noted in the same side foot. After clinical and radiological evaluation an excision biopsy was planned for both sites. The specimen sent for histopathological evaluation revealed angiomyolipoma with identical characteristics in the two locations and was HMB45 immunostain negative. Patient was evaluated for possibility of tuberous sclerosis but there was no contributory evidence. Angiomyolipoma is typically a solitary renal tumor with rare occurrence at musculoskeletal sites. Multicentric variety is still infrequent. Intraarticular occurrence of angiomyolipoma presents a diagnostic challenge not only in terms of unfamiliarity but also unusual presentation with absence of characteristic immunostaining and multicentricity requiring careful exclusion of other lesions that may require a more radical approach for treatment.