Abstract
The infrapatellar (Hoffa’s) fat pad can be affected by a variety of tumours and tumour-like conditions which can occasionally present a diagnostic and therapeutic challenge to the treating surgeon. The fat pad can be affected by diffuse or solitary disease. Solitary tumours are relatively uncommon but with widespread uptake of Magnetic Resonance Imaging Scans (MRI) an increasing number of Hoffa’s fat pad tumours (HFP) are being recognized.
Between 1999 and 2008, 20 patients with HFP pathology referred to Oxford bone and soft tissue tumour service underwent resection and histological examination. Clinical records, imaging and histological findings were reviewed. Histology showed eight different diagnoses with Pigmented Villonodular Synovitis (PVNS) and ganglia being the most common pathology.
In one patient, MRI identified the cause of hypophosphataemic osteomalacia as an HFP phosphaturic mesen-chyma tumour despite the lack of local symptoms.
In conclusion, the majority of solitary HFP tumours are benign and maybe cystic or solid. MRI and plain radiographs are the imaging of choice. Cystic tumours maybe aspirated but the definitive treatment of both cystic and solid tumours should be open arthrotomy and excision biopsy. Arthroscopic resection is not advised, as complete excision is not always possible. None of the 20 patients in this series had a malignant tumour but this has been reported in the literature. Calcification on plain radiographs may indicate a malignant lesion. All patients in our series reported substantial improvement in symptoms following open tumour resection.
Correspondence should be addressed to: BASK c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
