title: Diagnostic pitfall: Mycobacterium avium complex pulmonary infection and positive ANCA.
abstract: We report the case of a 58-year-old female who presented with productive cough, weight loss, pulmonary nodular infiltrates and cavitations. She had a positive anti-neutrophil cytoplasmic antibodies (ANCA) test. A diagnosis of vasculitis was considered and a video-assisted thoracoscopic biopsy of the lung nodules was organised. However, prior to the biopsy, the sputum results revealed the presence of acid-fast bacilli, which were identified as Mycobacterium avium complex. A repeat ANCA assay was positive for atypical ANCA with negative proteinase-3 and myeloperoxidase titres. The patient was treated with rifampicin, ethambutol and clarithromycin with clinical and radiological improvement. The objective of this report is to highlight a rare association between positive ANCA titres and a non-tuberculous mycobacterial infection as a misdiagnosis and treatment of this patient with immunosuppressive therapy might have led to serious consequences.
authors.affiliation: Department of Respiratory Medicine, Castle Hill Hospital, Castle Road, Hull, East Yorkshire, UK, HU16 5JQ. sfaruqi@doctors.net.uk
authors.forename: Shoaib
authors.initials: S
authors.lastname: Faruqi
authors.forename: Jack A
authors.initials: JA
authors.lastname: Kastelik
authors.forename: Damian V
authors.initials: DV
authors.lastname: McGivern
mesh_terms: D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood; D001706:Biopsy; D017291:Clarithromycin / Q000627:therapeutic use; D003937:Diagnosis, Differential; D004359:Drug Therapy, Combination; D004977:Ethambutol / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology*; D012293:Rifampin / Q000627:therapeutic use; D013183:Sputum / Q000382:microbiology; D020775:Thoracic Surgery, Video-Assisted; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology*; D014657:Vasculitis / Q000175:diagnosis
chemical_list: D000904:Antibiotics, Antitubercular; D019268:Antibodies, Antineutrophil Cytoplasmic; D004977:Ethambutol; D017291:Clarithromycin; D012293:Rifampin