A 69-year-old male ex-smoker (five packs/year) presented to our clinic with a routine spirometry showing a mild restriction (FEV1=2.11 l, 72 % of predicted; FVC=2.69 l, 69 % of predicted; FEV1/FVC=0.78). He had no respiratory complaints, including cough, sputum production or dyspnoea, and denied any other symptoms, such as malaise, fever or weight loss. His medical history included hypertension, diabetes and dyslipidaemia, for which he received medications, and past surgeries for nephrolithiasis, ocular melanoma and basal cell carcinoma of the scalp. Ten years prior to presentation he had a positive tuberculin skin test (17 mm), for which he was not treated.
Physical examination revealed diminished breath sounds and dullness to percussion in the left lung base, and the chest roentgenogram showed a medium-sized left pleural effusion. Laboratory tests showed a C-reactive protein (CRP) level of 53 mg dl-1 (reference range, 0 to 5). Complete blood count, including leukocyte and differential count, was normal (9460 cell mul-1 total leukocytes with 59 % neutrophils, 30 % lymphocytes, 9 % monocytes,and 1 % each of eosinophils and basophils) and so were his renal and liver functions. An FDG-PET/CT was performed, which showed a left pleural effusion with FDG-avid thickening of the basal dorsal pleura (shown in Fig. 1). There neither lymphadenopathy nor other abnormalities in the lungs or in the rest of the body.
Thoracocentesis was performed and a total of 700 cc of clear fluid was drained. Analysis revealed an exudate with lymphocyte predominance (93 %). Lactic dehydrogenase (LDH) and protein levels were mildly elevated. Adenosine deaminase level was not measured. Cytological examination did not show malignant cells. No bacteria were detected in bacterial cultures or by Ziehl-Neelsen staining of the fluid and polymerase chain reaction (PCR) for TB was negative. Serum immunoglobulin and anti-interferon-gamma auto-antibody levels were not performed. However,   M. abscessus   was isolated in one out of three sputum cultures.
Thoracoscopic inspection of the left pleural cavity revealed adhesions at the lung base, in addition to multiple small white lesions of the parietal pleura in this area. Pleural biopsies were taken, which demonstrated well-formed epithelioid and giant cell granulomas with tiny foci of central necrosis in some of them, consistent with granulomatous pleuritis (shown in Fig. 2). Cultures that were taken from the pleura and from the effusion during the surgery grew   M. xenopi  . Consequently, the   M. abscessus   in the sputum was considered a contamination, and the patient was diagnosed with granulomatous pleuritis due to   M. xenopi  .
Antimycobacterial therapy was initiated with isoniazid, rifampin and ethambutol. However, treatment was stopped after 2 months due to arthralgias. By that time, the serum CRP level was 2 mg dl-1 and a repeat chest CT showed resorption of the pleural effusion with some residual pleural thickening. At the last follow-up 9 months after the initial presentation, the patient feels well and a chest radiograph shows mild pleural thickening.