MARcH, i6 LOCALIZED NODULAR SYNOVITIS OF THE KNEE: A REPORT OF TWO CASES WITH ABNORMAL ARTHROGRAMS* ABSTRACT: By THOMAS G. GOERGEN, M.D.,t DONALD RESNICK, M.D.,t and GEM NIWAYAMA, M.D4 SAN DiEGO, CALIFORNIA The anthrognaphic appearance in two cases of localized PVS of the knee involving the region of the infrapatellar fat pad is reported. Lesions in this area may present with confusing symptomatology, and the true abnormality may be overlooked in a search for a meniscal lesion. The anthrogmaphic picture is non-specific and a number of entities must be considered. P IGMENTED villonodular synovitis (PVS) is a benign proliferative disease of synovial tissue which may be either diffuse on localized and nodular. Preoperative diagnosis by double contrast arthnogmaphy has been reported in the diffuse form of the disease,9 but there are no reports using arthnography for diagnosis of the less common nodular form. Recently, we have seen two cases of nodular PVS of the knee with arthrographic abnormalities localized to the region of the infrapatellar fat pad. A paucity of material describing the normal arthrographic appearance of this region led to further investigation. REPORT OF CASES CASE I. A 25 year old man complained of a popping sensation in his right knee, present for five months, with intermittent locking. Clinical examination revealed audible and palpable clicking with flexion and with forceable extension in internal rotation. Arthrography showed normal menisci, but a prominence was noted in the region of the infrapatellar fat pad (Fig. IA). Because of clinical findings, the lateral meniscus was removed, but the clicking persisted. Further in traoperative investigation showed a large fibrous mass, which appeared to arise from the infrapatellar fat pad which was then excised. On gross examination a firm, wellcircumscribed mass measuring 2.5X2X2 cm was attached to adjacent adipose tissue (Fig. IB). Histologic study revealed fibrous proliferation with many histiocytes, occasional foamy histiocytes, and multinucleated giant cells, many containing hemosiderin pigment (Fig. i, CandD). CASE II. A I 5 year old girl complained of right knee pain and recurrent buckling following a bicycle accident one year prior to examination. The clinical interpretation was a torn medial meniscus, but an arthrogram revealed normal menisci. Retrospectively, a prominent intraarticular bulge in the region of the infrapatellar fat pad was present on the overhead lateral view (Fig. 2A). A few weeks later she twisted her knee which locked in 10#{176} of flexion. At surgery, a large pedunculated mass measuring 4 X 2 X I cm extended into the intercondylar notch from the region of the infrapatellar fat pad. It was partially attached to the ligamentum mucosum. There was surrounding synovial inflammation. Histologic examination revealed many spindle shaped cells with formation of collagen fibers. Hemosiderin-laden m acrophages with multinucleated giant cells and foamy histiocytes were present (Fig. 2B). DISCUSSION The first description of the entity now known as PVS is credited to Chassignac (1852) in a case report which he called cancer of the tendon sheath. Jaffc et al.5 introduced the term PVS in i 941, stressed the benign course of the disease, and raised a From the Departments of Radiology,t and Pathology4 Veterans Administration and University Hospitals, University of California at San Diego. 647
648 Goergen, Resnick and Niwayama MARcia, i6 FIG. I. Case I. (A) On a lateral roentgenogram of the flexed knee following double-contrast arthrography, the nodular mass is clearly identifiable (arrows). (B) A photograph of the removed and sectioned specimen reveals a fibrous well-circumscribed mass. (C) A photomicrograph (X 135) outlines fibrous proliferation with a villonodular pattern, pigmented cells (arrow), and occasional giant cells (arrowhead). (D) At a higher power of magnification (X54o), round and spindle-shaped cells are present with scattered areas of pigmentation. the possibility of an inflammatory etiology. Exclusive of hand lesions (giant-cell tumor of the tendon sheath), the knee is the most commonly involved joint, and many cases ofdiffuse involvement have been described. Reports of the localized nodular form in the knee have been less frequent. To our knowledge, arthrographic findings have not been reported in nodular PVS. In these two cases, the history suggested a mechanical derangement of the knee involving the menisci. Both patients experienced locking and no masses were palpable. In each case, at surgery a solitary mass was present, firmly attached to the synovium in the region of the infrapatellar fat pad. The lesions were excised and neither has mecurred. Histologic evaluation revealed 11- brous proliferation, a combination of histiocytes, multinucleated giant cells, and hemosidenin-laden macrophages, typical of localized nodular synovitis. In diffuse PVS, the clinical setting usually includes a young adult with chronic knee pain, joint stiffness, synovial thickening, palpable masses, and semosanguincous effusion. The typical amthrographic appearance of the diffuse form is an enlarged joint cavity in association with irregular masses containing villous synovial projections. Patients with localized nodular PVS in the knee usually lack the chronic inflammatory pattern of the diffuse form and most often present with symptoms suggesting a mechanical problem.3 In the absence of a palpable mass, the diagnosis is elusive. Preoperative arthrography may be obtained. Anthrographic technique usually stresses careful, coned examination of the menisci, with less attention directed toward lesions in other parts of the joint. Thus, a localized mass, especially in sites other than
VOL. 126, No. 3 Localized Nodular Synovitis of the Knee 649 FIG. 2. Case II. On a lateral roentgenogram of the flexed knee following double-contrast arthrography, a wellcircumscribed shadow (arrows) projects into the anterior aspect of the joint. (B) A photomicrograph (X54o) outlines fibrous tissue admixed with round and spindle-shaped cells. Mildly pigmented cells are occasionally noted (arrow). the suprapatellar bumsa, may be overlooked. Although the nodular masses in localized PVS may be attached to the synovium at any site in the joint or even to a meniscus, our cases are unusual because the masses arose adjacent to the infrapatellar fat pad. The infmapatellar fat pad is an extrasynovial intracapsular structure situated between the patcllam tendon and femoral condyles (Fig. 3A). Synovium reflects oven the fat pad, and a triangular fold, the ligamentum mucosum (alan fold), extends upward and posteriorly to attach in the intercondylar notch. The normal arthrogram outlines a smooth synovial covering over the fat pad. It is usually concave but may rarely be straight or slightly convex in appearance, and is best evaluated on the slightly flexed lateral film (Fig. 3B). A small synovial recess may be present under the inferior portion of the fat pad. Several entities may produce a localized mass or synovial irregularity in the region of the infrapatellar fat pad. Recurrent trauma and inflammation of the fat pad lead to formation of hypertrophic villi which may project into the joint.7 Such damage has been noted in association with meniscal lesions and has also been described as a separate clinical entity, Hoffa s disease.4 Tissue from a medial meniscus tear may displace the fat pad, producing a mass. Similar displacement may rarely result from an intra-articulam ganglion arising from the alar fold ofsvnovium.6 Uncalcified intra-articular bodies may locate in the space over the fat pad between the femoral condyles.8 Finally, other rare synovial tumors such as fibromas, hemangiomas,2 or giant cell tumors7 may produce localized amthrographic defects.
6o Goergen, Resnick and Niwayama MARCH, 1976 FIG. 3. Anatomy and normal arthrography. (A) A photograph of a sagittal section of a cadavenic knee demonstrates the infrapatellar fat pad (straight arrow) beneath the patellar tendon (curved arrow). Synovium is reflected over the fat pad (arrowhead) and a small recess is located beneath the fat pad (open arrow). ( B) A lateral view of a normal double-contrast arthrogram reveals a smooth concave synovial covering over the fat pad (arrowhead) and a small inferior synovial recess (open arrow). Donald Resnick, M.D. Department of Radiology Veterans Administration Hospital 3350 La Jolla Village Drive San Diego, California 92161 REFERENCES I. CHA5SIGNAC, C. M. E. Cancer de la game des tendons. Gaz. Hop. Civ. Milit., i 852, 47, I 8- I 86. 2. FORREST, j., and STAPLE, T. W. Synovial hemangioma of knee: demonstration by arthrography and arteriography. AM. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1971, 112, 512-516. 3. GRANOWITZ, S. P., and MANKIN, H. J. Localized pigmented villonodular synovitis of knee. 7. Bone & Joint Surg., 967, 49-A, I 22-I 28. 4. HOFFA, A. Uber rontgenbilder nach einblasong von sauerstoff in das kniegelenk. Ben. K/in. Wschr., 1906, 43, 28-32. 5. JAFFE, H. L., LICHTENSTEIN, L., and SUTRO, C. J. Pigmented villonodulan synovitis, bunsitis, and tenosynovitis: discussion of synovial and bursal equivalents of tenosynovial lesion commonly denoted as xanthoma, xanthogranuloma, giant cell tumor, or myeloplexoma of tendon sheath, with some considerations of this tendon sheath lesion itself. Arch. Pathol., 1941, 3!, 73 1-765. 6. MUCKLE, D. S., and MANAHAN, P. Intra-articular ganglion of knee. 7. Bone & Joint Surg., 1972, 54-B, 520-52!. 7. RICKLIN, P., RUTTIMANN, A., and DEL BUONO, M. S. Meniscus lesions. In: Practical Problems of Clinical Diagnosis, Arthrography, and Therapy. Grune & Stratton, New York, 1971. 8. STAPLE, T. W. Extrameniscal lesions demonstrated by double-contrast arthrography of knee. Radiology, 1972, 102, 311-319. 9. WOLFE, R. D., and GIULIANO, V. J. Doublecontrast arthrography in diagnosis of pigmented villonodular synovitis of knee. AM. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1970, 110, 793-799.
This article has been cited by: 1. Adam Greenspan, Javier Beltran. Tumoren und tumorartige L?sionen (Tumor-like Lesions) der Gelenke 865-885. [CrossRef] 2. Donald Resnick, Mark J. Kransdorf. Tumors and Tumor-Like Lesions of Soft Tissues 1199-1244. [CrossRef] 3. William P. Docken. 1979. Pigmented villonodular synovitis: A review with illustrative case reports. Seminars in Arthritis and Rheumatism 9:1, 1-22. [CrossRef]