Microscopic polyangiitis (MPA) is a systemic necrotizing vasculitis characterised by inflammation of the small blood vessels, the absence of granulommas on histopathological specimens, with few or no immune deposits and the presence of circulating anti-neutrophil cytoplasmic antibodies (ANCAs). The classic pulmonary manifestation is diffuse alveolar haemorrhage (DAH), but its association with pulmonary fibrosis (PF) has been increasingly reported and may be the first manifestation of MPA. Our aim was to evaluate MPA patients with PF and compare their characteristics and evolution to those of MPA patients without PF. We conducted a retrospective review of MPA patients followed in our hospital over a 15-year period. They were divided into two subgroups, with PF (MPA-PF) and without PF (MPA-non PF), and their clinical and functional features were compared. Nine of the 28 patients were classified as MPA-PF (32%). This subgroup showed significantly more respiratory symptoms and higher mortality than MPA-non PF subgroup. The most frequent chest computed tomographic pattern of PF was usual interstitial pneumonia. PF preceded other manifestations of vasculitis in five patients and occurred simultaneously in the remaining four. During the follow-up period, four deaths were reported in the MPA-PF subgroup. No deaths were registered in the MPA-non PF subgroup. We found a high prevalence of MPA-PF patients (32%), most of whom had a poor outcome and PF was often the first manifestation of the disease.

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The diffuse cystic lung diseases (DCLDs) are a pathophysiologically heterogeneous processes characterized by the presence of multiple thin-walled, air-filled spaces within the pulmonary parenchyma. The most common causes of DCLD are lymphangioleiomyomatosis (LAM) and pulmonary Langerhans cell histiocytosis (PLCH).DCLD develops rarely as a result of malignancy, typically secondary to metastases from peripheral sarcomas and mesenchymal tumors. DCLD have also been reported in a variety of other metastatic disease such as adenocarcinoma.Our case describes a patient with DCLD as a result of metastatic colorectal adenocarcinoma.

Differential diagnosis of lymphocytic pleural effusions between tuberculous (TBE) and malignant (ME) effusion is usually difficult in daily practice. Our aim was to develop a score to differentiate TBE from ME effusions. A cohort of 138 consecutive patients with pleural effusion was prospectively studied from May 2014 through June 2017. Glucose, lactate dehydrogenase (LDH), proteins, white cell count, lactic acid, and pH in the pleural fluid were measured. Pleural effusions other than lymphocytic, patients with a final diagnosis other than tuberculosis or malignancy, and patients who met Light’s criteria for transudate were excluded. Eighty-two samples (47 TBE and 35 ME) were included in the analysis. Using logistic regression analysis and Wald test, we developed a score including age, glucose, proteins, and lactic acid. The receiver operating characteristic curve (ROC) for the score was determined, and the area under the curve (AUC) was calculated. A cutoff of eight points was required to achieve 93.5% sensitivity, 78% specificity, and a likelihood ratio of 4.26 to distinguish tuberculosis from malignant pleural effusion. The AUC of the score was 0.915 (95% CI = 0.82–0.96).

The utility of the adenosine deaminase (ADA) assay in the diagnosis of patients with pleural tuberculosis (TB) and human immunodeficiency virus (HIV) infection is controversial. Forty-eight HIV positive patients with pleural effusion were evaluated; ADA assay was obtained in forty-three of them. Twenty-five patients presented diagnosis of TB. Patients with diagnosis of TB showed a median value of ADA of 70 IU/L (interquartile range (IQR) 41–89) and the non-TB group a median of 27.5 IU/L (IQR 13.5–52). Patients with diagnosis of TB had a median cluster of differentiation 4 (CD4) count of 174 (IQR 86–274) and the non-TB group had a median of 134 (IQR 71–371). Receiver operating characteristic curve was performed with an area under the curve of 0.79. The best cut-off obtained was 35 IU/L with a sensibility of 80% and a specificity of 66%. There was no correlation between CD4 lymphocytes count and the value of ADA in the TB patient group.

Introduction: Pulmonary diseases due to non-tuberculous mycobacterium (NTM) lung infection in HIV-negative patients are rarely described in the literature. Currently, NTM consist of more than 150 species, and they are globally ubiquitous in both natural and man-made environments.The objective of this study was to define the most frequent species of NTM causing pulmonary disease in HIVnegative patients in the city of Buenos Aires, Argentina. The prevalence of pulmonary diseases caused by NTM is difficult to determine since the isolation of NTM does not necessarily indicate disease. Methods: A retrospective review of all the respiratory cultures positive for NTM in the Bacteriology Laboratory of Posadas Hospital between January 2010 and December 2015 was performed. 31 patients without Human Immunodeficiency Virus (HIV) from whom NTM was isolated in respiratory samples, which fulfilled diagnostic criteria for NTM disease were included. Results: The mean age was 50 years at the time of the diagnosis (SD ± 17.2); and 19 patients (61.3%) were males. Mycobacterium kansasii was the most commonly isolated NTM (68%) followed by Mycobacterium avium Complex (MAC) (19%). M. kansasii was the most common cause of pulmonary infection by NTM in these HIV-negative patients. Cultures should be performed to identify the species and to treat accordingly. 46% of the patients included in the study, there was no evidence of risk factors. Only 32% of the subjects had respiratory comorbidities, and the most common radiologic finding was cavitation (55%). Discussion: Our study indicates that M. kansasii is the primary etiology of NTM pulmonary disease in HIV-negative patients in our service area in Buenos Aires. This finding supports the consideration that patients with symptoms compatible with pulmonary tuberculosis should also be evaluated for NTM with appropriate acid-fast bacilli cultures, as treatment regimens differ vastly according to the specific pathogen isolated, although clinical and radiographic presentations may have overlapping features. The possibility of M. kansasii pulmonary disease or other NTM should be considered in patients treated empirically for TB without appropriate clinical response.

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