95 8 LETTERS LE cells in intermittent hydrarthrosis To the Editor: In vivo synovial fluid LE cells have been demonstrated in systemic lupus erythematosus (SLE) and rheumatoid arthritis (1,2). We report here a case of a young woman with clinical and laboratory findings consistent with the diagnosis of intermittent hydrarthrosis (IHA) in whom synovial fluid LE cells and positive tests for synovial fluid antinuclear antibody were demonstrated in the absence of any further evidence for the diagnosis of SLE. A 23-year-old woman first experienced painless swelling of the right knee at age 11 coincident with menarche. This episode heralded a predictable cycle of recurrent attacks, occurring 6 to 7 times per year and more prominent in winter months. The knee would swell rapidly but without pain, local heat, erythema, or morning stiffness and it resolved spontaneously within 3 to 4 days. There was no response to salicylates, nonsteroidal antiinflammatory agents, or repeated intraarticular corticosteroid injections. No other joints were affected and there were no other symptoms suggestive of an underlying connective tissue disorder. Repeated serologic profiles, synovianalyses, and roentgenograms failed to reveal any abnormalities. At age 22, the patient began to experience identical complaints in the left knee as well. One year of persistent symptoms led to hospital admission for arthroscopy. Physical examination revealed only mild bogginess and positive fluid waves in both knees. Range of motion was preserved; there was no creptitus or specific signs of patellofemoral joint disease. Laboratory data included a normal complete blood count, serum uric acid, sedimentation rate, urinalysis, serum complements, and a negative VDRL. Tests for serum antinuclear antibody, rheumatoid factor, antibody to native DNA, and extractable nuclear antigen all gave negative results. Synovial fluid was clear and viscous with normal total protein and complements. The cell count was 2,200 with 85% mononuclear cells. Wright’s stain of synovial fluid revealed LE cells as well as numerous tart cells in both knees. Followup testing revealed a positive ANA in the right knee at a titer of 1 :40 and in the left knee a titer of 1 : 100, both of homogeneous pattern. AntiDNA testing of synovial fluid by Crithidia luciliae immunofluorescence was negative in both knees. Agarose gel electrophoresis of synovial fluid revealed a normal pattern. Bilateral arthroscopic examination demon- strai d i durated and thicken d synovium with multiple villous projections. The patellae manifested minimal fibrillation but the menisci were unremarkable and no pannus was noted. Biopsies were not taken and the patient was discharged without a definite diagnosis. Antibodies to deoxyribonucleoprotein are responsible for the LE cell phenomenon (3). Although of historical importance in diagnosing SLE (4) and included as a preliminary criterion for classification of SLE ( 5 ) , LE cells have been demonstrated in a variety of connective tissue disorders, immunopathic diseases, chronic infections, and in the aged (6). These conditions share the features of chronicity and inflammation. A recent textbook of rheumatology states that advances in immunologic laboratory testing have made the LE cell test obsolete and rarely helpful in differential diagnosis (7). Intermittent hydrarthrosis describes a disease of unknown etiology typified by recurrent joint effusions, usually involving a single knee, and occurring with distinctive periodicity (8). Cardinal signs of inflammation are minimal or absent and laboratory workup is usually nonrevealing. The natural history of IHA remains obscure; it has a tendency toward spontaneous remission. In some patients, however, accelerated degenerative arthritis or evolution to classic rheumatoid arthritis is the rule. The case reported here has certain laboratory features suggestive of SLE although such a diagnosis is clearly not warranted at this time. The synovial fluid abnormalities may reflect only epiphenomena of chronic inflammation. The rarity of IHA precludes accumulation of large numbers of patients. We would be curious if other investigators could confirm our findings in this single case. JAMESR. SEIBOLD, MD LAWRENCE R. WECHSLER, MD ROY J. CAMMARATA, MD University of Pittsburgh School of Medicine Department of Medicine Pittsburgh, PA I5261 REFERENCES 1. Hollander JL, Reginato A, Torralba TP: Examination of synovial fluid as a diagnostic aid in arthritis. Med Clin N Am 50:1281-1293, 1966 2. Hunder GG, Pierre RV: In vivo LE cell formation in synovial fluid. Arthritis Rheum 13:448-451, 1970 LETTERS 3. Tan EM: Systemic lupus erythematosus-immunologic aspects, Arthritis and Allied Conditions. Ninth edition. Edited by DJ McCarty. Philadelphia, Lea & Febiger, 1979, pp 7 15-722 4. Hargraves MM: The LE cell phenomenon. Adv Intern Med 6:133-160, 1954 5. Cohen AS, Reynolds WE, Franklin EC, Kulka JP, Ropes MW, Shulman LE, Wallace SL: Preliminary criteria for the classification of systemic lupus erythematosus. Bull Rheum Dis 2 1:643-648, 1971 6. Friou GJ: The L.E. cell phenomenon and antinuclear antibodies, Arthritis and Allied Conditions. Eighth edition. Edited by JL Hollander, DJ McCarty. Philadelphia, Lea & Febiger, 1972 pp 172-194 7. McCarty DJ: Synovial fluid, Arthritis and Allied Conditions. Ninth edition. Edited by DJ McCarty. Philadelphia, Lea & Febiger, 1979, pp 51-69 8. Ehrlich GE: Intermittent and periodic arthritic syndromes, Arthritis and Allied Conditions. ~ i n edition. ~ h Edited by DJ McCarty. Philadelphia, Lea & Febiger, 1979, pp 663680 Retrocardiac mass: A clue to the tuberculous nature of monarthritis To the Editor: The diagnosis of monarticular diseases often defies the clinician. Clues to their diagnoses, when present, are welcomed with relief. An asymptomatic retrocardiac mass found in the routine chest x-ray of a patient with unilateral knee swelling gave a clue to its tuberculous nature and evidenced a second typical manifestation of musculoskeletal tuberculosis: Pott’s disease (1). Case report. This 20-year-old woman consulted our service because of pain and swelling of the left knee that had lasted 7 months. During this time she had lost 10 kg and had become increasingly weaker. She had occasionally noticed low back pain which increased when she bent over. Physical examination revealed only the swelling of the left knee with both synovitis and effusion. This was aspirated. The fluid obtained was pale yellow, clear, with few leukocytes. A Singer-Plotz test for rheumatoid factor in the synovial fluid was positive at a titer of 1 :320; a mucin-clot was grade 11. Cultures were negative. Laboratory tests were essentially normal, including serum rheumatoid factor, antinuclear antibodies, and LE clot test. Tuberculin and serologic tests for tuberculosis were positive. The roentgenogram of the chest revealed a lobulated mass in the lower mediastinum posterior to the 959 heart, which seemed to extend below the diaphragm (Figure 1). Roentgenograms of the spine as well as tomograms (Figure 2) revealed loss of height of the tenth thoracic vertebra with erosion of the lower and upper epiphyseal plateaus of the tenth and eleventh thoracic vertebrae respectively. The mass was shown to extend from the ninth through the twelfth thoracic vertebrae with a lobulated appearance which indented at the level of the tenth vertebral space. This image was characteristic of Pott’s disease. Svnovectomv of the left knee showed chronic granulomatous inflammation with acid fast bacilli. Treatment with rifampicin, ethambutol, and isoniazid resulted in gradual diminution and disappearance of the mediastinal mass. Other clues to the tuberculous nature Of this abscess, despite its low thoracic level, Were the lobulated appearance, its extension below the diaphragm, and the coincident indolent monarthritis. The absence of pulmonary tuberculosis did not rule out this diagnosis since approximately 50% of patients with skeletal involvement have no detectable pulmonary disease (1). Skeletal disease is probably the most common form of extrapulmonary tuberculosis (1, 2). When it af- Figure 1. Chest roentgenogram of patient with tuberculous monarthritis.