Organizing pneumonia with atypical computed tomography findings in Sjögren's syndrome.

Abstract

Dear Editor, Primary Sjögren's syndrome (PSS) is a systemic autoimmune disease, characterized by keratoconjunctivitis sicca and xerostomia resulting from lymphocytic infiltrates of the lacrimal and salivary glands.1 In PSS, pulmonary manifestations are observed in up to 75% of cases, in the form of nonspecific interstitial pneumonitis (NSIP), usually interstitial pneumonitis (UIP), lymphocytic interstitial pneumonitis and bronchiolitis. The commonest form of interstitial lung disease is NSIP.2 Organizing pneumonia (OP), formerly known as bronchiolitis obliterans OP, is a subacute pulmonary illness characterized by buds of granulation tissue in the bronchioles and alveolar ducts, with extension of organization to the alveoli.3 OP has been reported in only a few cases during the course of confirmed PSS, but most of them had typical OP computed tomography (CT) findings.4 Herein, we describe a case exhibiting the less frequent imaging pattern of OP in PSS. A 52-year-old woman was admitted to our hospital complaining of having had a cough and fever up to 38°C, for several days. Three years previously in this patient, we diagnosed PSS by fulfilling the American–European criteria for PSS upon observation of symptoms of dryness of the mouth and eyes, positive Schirmer's test, positive fluorescent antinuclear antibody test, elevated anti-Ro/La antibodies, and positive salivary gland scintigraphy findings. The patient was never a smoker. On admission, a chest X-ray revealed small nodular infiltration on the right upper peripheral portion. A high-resolution CT (HRCT) scan of the lungs revealed centrilobular nodules with a tree-in-bud pattern on the right upper posterior segment (Fig. 1). The patient was treated for community-acquired pneumonia. Despite antibiotic therapy for 18 days, the symptoms did not abate. Bronchoscopy with bronchoalveolar lavage showed no endobronchial masses, and the differential cell count thereof revealed mixed alveolitis (neutrophils 21%, macrophages 38%, lymphocytes 38% and eosinophils 3%). In bacteriological tests, acid-fast stain reactivity, Mycobacterium tuberculosis – polymerase chain reaction (PCR), and culture of the bronchial washing were all negative. There was no evidence of malignancy. Fungus cultures also were negative. Thus, we performed video-assisted thoracoscopic surgery (VATS) biopsy, which showed organizing tissue within alveolar ducts, composed of actively proliferating loose fibro-connective tissue containing scattered inflammatory cells, compatible with OP (Fig. 2). There was no history of radiotherapy or medications5 that may cause OP. Therefore, our diagnosis was secondary OP with PSS. The patient was started on oral prednisolone 0.5 mg/kg/day, with improvement of symptoms and marked clearing of pulmonary infiltrates at a 2-month follow-up. Follow-up CT scans 9, 12 and 24 months after onset revealed no recurrence of OP. OP is an inflammatory and fibro-proliferative reaction of the lung. The concept of OP was introduced in the 2002 consensus statement of the American Thoracic Society and the European Respiratory Society for the classification of idiopathic interstitial pneumonia,6, 7 to distinguish cryptogenic OP (COP) from cases associated with various clinical conditions related to infections, drugs, radiotherapy and connective tissue disease.3 There were no major differences between the clinical features of COP and secondary OP. However, the classification of OP as either COP or secondary OP is clinically important, as the management of patients with secondary OP includes not only treatment of the OP but also the management of underlying disease and avoidance of any known offending agent. Infections are the most common cause of secondary OP.5 Secondary OP associated with connective tissue disease is more frequently associated with rheumatoid arthritis and polymyositis. PSS is not usually associated with OP and only a few cases have been reported in the literature.4, 8, 9 In most published reports, the patients have exhibited CT findings typical of OP. Reportedly, the typical CT pattern of OP is present in 60–90% of cases.10 It is characterized by bilateral patchy areas of consolidation, often triangular or polygonal in shape, in the peripheral subpleural regions but also peribronchial, and often located in the lower lobes.10 However, the CT of our case revealed a micronodular lesion characterized by small ill-defined centrilobular nodules, combined with the tree-in-bud pattern. This finding is similar to endobronchial spread of infectious bronchiolitis such as that caused by tuberculosis or nontuberculous mycobacteria (NTM). Thus, we performed flexible bronchoscopy to obtain bronchoalveolar lavage samples, and lung biopsy to enable discrimination from other infectious diseases. In most cases, there is a good response to corticosteroids at a dose of 0.5–1.0 mg/kg/day, like our present patient. However, in some cases there is little or no improvement. In these cases, cytotoxic drugs, such as azathioprine or cyclophosphamide, may be considered.3 In conclusion, we have described a case of secondary OP with an atypical CT pattern, associated with PSS. Where diagnosis is unclear after a thorough clinical and radiographic evaluation, such as in our patient, lung biopsy should be performed to establish the underlying histopathology, particularly the atypical features of the disease. No conflict of interest.