Diffuse pigmented villonodular synovitis: An exuberant presentation

Abstract

We present a case of a 44-year-old male, with a history of right knee swelling from insidious onset and two years of progressive evolution. There was not history of trauma or other associated symptoms (fever, pain, asthenia, weight loss, and other swollen joints). He was referred to the orthopedic consultation by the primary health care specialist, after unspecific knee magnetic resonance imaging (MRI) and needle arthrocentesis, followed by unsuccessful physical therapy sessions. At physical exploration it was clear a tender and voluminous swelling of the right knee, especially at the sub-quadricipital bursa, without other clear inflammatory signs (Figure 1). The patient denied other symptoms or even knee pain at exploration, although it as present on daily activities. The X-ray images were considered normal, without bony lesions. At the MRI, there was a signal increase with heterogeneous shape, especially at sub-quadriceps and suprapatellar bursa, without bony erosion (Figure 2). However, small areas of hippo-signal were observed which determine some intra-sac septations and vegetations, aspects which may be compatible with pigmented villonodular synovitis (PVNS). He has proposed to knee arthroscopy and needle arthrocentesis for final diagnosis and further treatment. It was performed under general anesthesia, the initial arthrocentesis revealed a pathognomonic xanthochromic synovial fluid (Figure 3) >120 cc and the arthroscopy images (Figure 4) were clear of vascularized polypus formations spread through the entire synovial cavity, with higher density in sub-quadricipital area. Tissue and liquid samples were acquired for cytochemical, histologic, and microbiological identification. The histologic analysis revealed characteristic of chronic inflammation with, reactive hyperplasia of synovial tissue and presence of high hemosiderin deposits in the synovial stroma (Figure 5A). At a second surgical time, after confirmation of diagnosis, the patient was submitted to total synovectomy with necessity of conversion from arthroscopic to open synovectomy (Figure 5B). Postoperative period and rehabilitation showed with no complications. At two years of follow-up there is still no clinical or imagiological sign of recurrence, and maintains annual consultation.